provided information to farmers that helped thembecome more economically viable while practicinggood stewardship of the land. But after a successfuleight years, MISA is in trouble; its creative leadershipin sustainable agriculture may be crippled, becausethe key to MISA’s success is also the key to its cur-rent conflict with the University administration—itsstructure and governance. MISA was established as aunique partnership between the College ofAgriculture, Food and Environmental Sciences(COAFES) and the Sustainers’ Coalition, a group oforganizations advocating sustainable agriculture. Thispartnership has shared an unprecedented cooperative

arrangement in MISA’s man-agement.

The Founding of MISAIn 1987, five communityorganizations joined forces toform the Sustainers’Coalition, for the purpose ofovercoming the University ofMinnesota’s resistance to sus-tainable agriculture researchand education. The coalitionincluded the OrganicGrowers and BuyersAssociation, Minnesota

Food Association, Joint Religious LegislativeCoalition, Land Stewardship Project, and theMinnesota Project (today it also includes theInstitute for Agriculture and Trade Policy and theSustainable Farming Association of Minnesota).

“I don’t think the problem at the University is somuch active hostility to sustainable agriculture as it isa lack of information about what the critics of con-ventional agriculture are saying,” journalist PaulGruchow told Ken Taylor, a leader of the Sustainers’Coalition, after hearing Eugene Allen, then Dean of

The land grant colleges of agriculture in theUnited States have proudly led the countryalong the path to an industrial food and

agriculture system, even though it has becomeincreasingly destructive to the environment andrural communities. In the midst of farm foreclo-sures in the 1980s, family-sized farmers felt ill-served by the advice of these institutions, and peo-ple began to realize that behind the successes ofhigh yielding crops and labor efficiency on thefarm were failures: soil erosion, contaminateddrinking water, streams filled with sediment, adecline in wildlife habitat and the loss of independ-ent family farmers.

When farmersand environmental-ly concerned citi-zens asked agricul-tural researchersand college admin-istrations to addressthese problems andlead farming to amore sustainablefuture, they weregenerally rebuffed.However, some-times they foundfriendly faculty who weren’t happy just doingresearch to improve the profits of agribusiness. Andin some states, they convinced legislators and col-lege administrations to open the door for smallalternative agriculture programs.

Minnesota was one of those states; citizen effortsled to the establishment in 1992 of the MinnesotaInstitute for Sustainable Agriculture (MISA) whichdeveloped innovative educational and research pro-grams that are widely recognized around the coun-try. It heightened a discussion about sustainability inagriculture within the University of Minnesota and Continued on page 4

ORGANIC FARMINGRESEARCH FOUNDATION

I N F O R M A T I O N B U L L E T I N

Winter 2001 Number 9

RESEARCH REVIEWS:

Apparatus Design andExperimental Protocol forOrganic Compost Teas. . . . . 9Richard Merrill and John McKeonCabrillo College,Soquel, CA

Effectiveness ofCompost Tea Extracts asDisease Suppressants inFresh Market Crops.. . . . .16Sylvia Welke,North Okanagon Organic Assoc.,Alberta, BC

Effect of DiseaseSuppressive Compostson Organic VegetableQuality, Compositionand Yield . . . . . . . . . . . . .21Anusuya Rangarajan,Cornell University,Ithaca, NY

Efficient Useof Organic NitrogenFertilizers. . . . . . . . . . . . . 26Mark Gaskell,UC-Cooperative Extension,Santa Maria, CA

Testing AlternativeParasiticides forOrganic LambProduction. . . . . . . . . . . .29Janet Allen,Dragon Mountain Farm,Quesnel, BC

❁

OFRF News. . . . . . . . . . . . . 2

Policy Program Notes. . . . . 6

Technical Program Notes. . 7

In Context: Compost Teas:A Brave New World. . . . . . 8

Grants AwardedFall 2000. . . . . . . . . . . . . .32

An Experiment in Partnership:The Minnesota Institute for Sustainable AgricultureDana Jackson

ORGANIC FARMINGRESEARCH FOUNDATION

B O A R D O F D I R E C T O R S

O f f i c e r s

Woody DeryckxPresident

Bentwood FarmsMalin, Oregon

Ron RosmannVice-president

Ron & Maria Rosmann & Sons FarmsHarlan, Iowa

Mary Jane EvansTreasurer

Veritable VegetableSan Francisco, California

Ingrid LundbergSecretary

Lundberg Family FarmsRichvale, California

❁

Helen AtthoweBiodesign

Missoula, Montana

Roger BlobaumBlobaum and Associates

Washington, DC

Jerry DeWittDepartment of Entomology

Iowa State UniversityAmes, Iowa

Tom DobbsDepartment of Economics

South Dakota State UniversityBrookings, South Dakota

Lewis GrantGrant Family Farms

Wellington, Colorado

Cynthia HizerHazelbrand Farm

Covington, Georgia

Betsy LydonEnvironmental Grantmakers

AssociationNew York, New York

Doug O’BrienO’Brien Consulting

Santa Cruz, California

Stephen PorterPorter Farms

Elba, New York

J.B. Pratt, Jr.Pratt Foods, Inc.

Shawnee, Oklahoma

Marianne SimmonsOnion Creek Farm

Dripping Springs, Texas

I N F O R M A T I O N B U L L E T I N

2

2001 – An Organic Odyssey

Now is a time of transition in many areas of ourworld, and organic is certainly one. We are enter-ing a new era in organic marketing with theUSDA’s recently released final Organic Rule.Overall the future looks promising for organicfarmers and consumers, but serious threatsremain in relation to GMO contamination andliability, costs to small farmers, and concentrationin the growing organic industry.

OFRF is gearing up to face these challenges as wecontinue to pursue our purpose: the improve-ment and widespread adoption of organic farm-ing practices. For us, it is also a time of transitionfrom our first decade of work to our second. Aswe pass this milestone, the OFRF Board ofDirectors is undertaking a major strategic plan-ning effort, with the goal of refining our visionand mission for the next five years. The JessieSmith Noyes Foundation has generously con-tributed $7,500 in support of this importantwork to prepare OFRF for the future.

The Strategic Planning Committee leading thisprocess includes three current board members,Vice President Ron Rosmann, Research &Education Committee Chair Jerry DeWitt, andMarianne Simmons; two former board mem-bers, SARE National Program Director JillAuburn, and OFRF Founding President MarkNielson; and two staffers, Bob Scowcroft andDon Burgett. Long-time nonprofit professionalDoug Ford is helping to ensure the success ofthe group’s work by advising on the process andfacilitating communications. With luck and a lotof thoughtful work, the Committee will present adraft strategic plan to the Board at its Spring2001 meeting.

More Staff, New Digs, and the Supportto Make It Possible

To meet the growing demands on our programs,we have added a part-time Policy Assistant to ourstaff. (Former Program Assistant Rebecca King isfilling this role for us until we hire a permanentstaffer this March!) This position will help PolicyProgram Director Mark Lipson address policyissues in greater detail and broaden the reach ofour policy analysis. We are also seeking an internto round out the policy team. Other new internpositions are available in our development, infor-mation and administrative programs.

Of course, with the growing workload and staff tohandle it, we have had to expand our office, too.As it turned out, we were packing up our thingsthe day after the announcement of the finalOrganic Rule, and we moved down the hall into aspace twice the size of our old one the followingday. Amazingly, and with a great deal of credit toProgram Associate Melissa Matthewson, we nevermissed a phone call (and there were plenty!), andwe were settled into the new office before the holi-days were over.

We would not be moving forward so positivelywithout your support. Our network of organicfarmers, consumers and businesses continues togrow and give generously to our work. We are par-ticularly grateful to the Clarence E. HellerCharitable Foundation for their recent two-yeargrant of $150,000 for general program support.The Heller Foundation’s trustees and staff are lead-ing advocates of more sustainable approaches toour food and farming systems, and they have sup-ported OFRF and many other worthy organiza-tions over the years.

As we deposit your contributions coming in nowin response to our year-end mailing, we are partic-ularly thankful to all of you who have sent usdonations of $10, $25 and $50. We work hard toearn your support, and we think of your gifts aswe use the money day-to-day. Together with thesupport of those who have chosen to give $100,$500 and more, we have already received morethan $30,000 from our year-end appeal.

O F R F S T A F F

Bob ScowcroftExecutive Director

Don BurgettDevelopment Assistant &

Information Services Coordinator

Rebecca KingPolicy Program Assistant

Mark LipsonPolicy Program Director

Melissa MatthewsonProgram Associate

Laura RidenourEvents Coordinator

Jane SoobyTechnical Program Coordinator

Erica WalzEditor, Information Bulletin

Coordinator, National Organic Farmers’ Survey

OFRF NEWS

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W I N T E R 2 0 0 1 N U M B E R 9

I N F O R M A T I O N B U L L E T I N

Erica WalzEditor/Typographer

WoodyDeryckx, Helen Atthowe, Cynthia HizerEditorial Advisors

Dianne CarterIllustration

PRINTED BYCommunity Printers

Santa Cruz, CA

The Information Bulletin is published by the Organic Farming

Research Foundation, a non-profit foundation dedicated to

fostering the improvement and widespread adoption of organic

farming practices. Our mailing address: P.O. Box 440, Santa

Cruz, California 95061, telephone: (831) 426-6606, fax: (831) 426-

6670, email: <research@ofrf.org>, web: www.ofrf.org. Material

in this publication may be reprinted with credit.

Research Reviews are the results of OFRF-funded research and

education projects. Project reports presented in this newsletter

are derived from materials submitted to OFRF by project coor-

dinators. These research and education projects may be sole-

ly supported by OFRF, or may involve other sources of support.

Acknowledgment of all project contributors and cooperators

is provided, wherever possible. For further information on these

projects, you may contact OFRF or the growers and

researchers listed with each review. The use of trade names or

commercial products published in these results does not con-

stitute any product endorsement or recommendation by

OFRF.

OUR MISSION • To sponsor research related to organic farming

practices • To disseminate research results to organic farmers

and to growers interested in adopting organic production sys-

tems • To educate the public and decision-makers about

organic farming issues

Printed on recycled-content paper. Please recycle.

We also greatly appreciate the companieswho each have contributed $1,000 ormore to our work since last summer:

Brown-Forman Corporation

Cascadian Farm / General Mills

Celestial Seasonings / Hain Group

CF Fresh

Earthbound Farm /

Natural Selection Foods

Epic Roots, Inc.

Fetzer Vineyards

The Lark Creek Inn

New Hope Natural Media

Paul Newman / Newman’s Own

Newman’s Own Organics

Tanimura & Antle

Veritable Vegetable

Whole Foods Market

Wolaver’s / Panorama Brewing Co.

Working Assets

Notable Events!

OFRF Events Coordinator LauraRidenour has had her plate full this fall,too—usually with delicious organic food!August brought a great thrill to ourNorthern California friends, as GrammyAward-winning singer-songwriter TracyChapman performed a concert to benefitOFRF and the UCSC Center forAgroecology & Sustainable FoodSystems’ Farm & GardenApprenticeship Program. Tracy alsostopped by our pre-concert dinner tothank everyone for supporting organicfarming! She also took time on stage totell the whole crowd about the importanceof organic agriculture and describe howshe had started gardening organically as alittle girl. The dinner was an all-organicfeast prepared by famed local chef JesseCool of Flea Street Café, making theevening delicious as well as memorable.

Following on the heels of the concert,OFRF held its Eighth Annual FallOrganic Benefit Luncheon at the LarkCreek Inn in Larkspur, CA. Sponsoredagain by Whole Foods Market, the mealwas a culinary collaboration of five greatchefs. It was wonderful to hear lead chefJohn Mitchell note how far we have comein the eight years since this annual eventbegan. Finding the ingredients for a com-pletely organic gourmet meal was very dif-ficult in the beginning, but this year hesaid they had no problem tracking downeverything they needed, from cooking oils,to spices, to organic chicken. The organicindustry has come a long way, indeed!

In December, Executive Director BobScowcroft spoke at the Tenth AnnualEnvironmental Media Awards in LosAngeles. Hosted by the EnvironmentalMedia Association (EMA), the event hon-ored outstanding film and TV work focusedon environmental issues. Organic food andfarming was the theme of the evening, withthe venue decorated in the style of a farmers'market, including stalls of produce allaround the dining area. The 700 industryattendees were treated to an all-organic mealprepared by top Los Angeles chefs. Chef andlong-time OFRF supporter DonnaPrizgintas coordinated the meal, and herstatement: "Eating is an environmental

activity," became the underlying theme ofthe event.

OFRF Receives Gift of PrimeInternet Real Estate!

In another first for us, Internet commercecompany WebMagic, Inc. has donated anonline domain name to OFRF. The unso-licited gift of Organically.com was valuedat $20,000 by a domain name appraisalfirm, and represents our first major virtualgift! We are glad that WebMagic CEOGreg McLemore identified us as a worthyrecipient for the domain and thank himfor the generous gift. OFRF does not cur-rently plan to use the domain name itself(we like our ofrf.org), and we invite any-one interested in acquiring the domain tocontact us (Don Burgett or BobScowcroft) at (831) 426-6606.

Looking ahead, Laura and the rest of thestaff have their hands full. The InauguralAssembly of the Scientific Congress onOrganic Agricultural Research (SCOAR)will take place in January in Pacific Grove,CA, in conjunction with the 21st annualEcological Farming Conference. Fundsfrom the USDA’s Initiative for FutureAgriculture and Food Systems (IFAFS) aresupporting SCOAR as part of the work ofthe Organic Agriculture Consortium ofOFRF and Ohio State, Iowa State, NorthCarolina State and Tufts Universities.

Next up will be Organic Day at the annualNatural Products Expo-West in Anaheimin March. This year, the usual OFRFOrganic Benefit Luncheon will moveinside the main pavilion, where we expectto serve up to 500 people an all-organicgourmet lunch. This will be more thandouble the attendance of our previous Expoluncheons! Expo organizers New HopeNatural Media wanted to increase our visi-bility at the Expo and encourage more ofthe retailers attending Thursday workshopsto experience what an organic meal can be.Chefs Donna Prizgintas and ChrisBlobaum will preside over the meal againthis year, so it is sure to be outstanding.

We hope you can join us for some of thefestivities, and we wish you a relaxing win-ter and an early start to your season!

—Don Burgett

COAFES, admit that he was not familiarwith Wendell Berry’s writing. This motivat-ed the Sustainers to propose a series of sem-inars in 1988 between university faculty andmembers of the Coalition, and theUniversity agreed to participate. A joint taskforce continued the dialogue, and exploredpossibilities for initiating a program ofresearch and education in sustainable agri-culture. A lengthy process ensued untilfinally, in 1992, the first MISA Board ofDirectors was named, and by-laws weredrawn up and approved by the Universityadministration and legal advisors. RichardJones, then COAFES Dean, committed$200,000 for the first year and $300,000per year to support MISA efforts for thenext four years.

One of a KindMISA is a unique entity; it’s not a college“department,” nor a sustainable agriculture“center,” such as those at the Universitiesof Wisconsin, Nebraska, Washington orthe University of California-Santa Cruz,nor a “program,” like the one at theUniversity of California-Davis. It wasn’testablished by state statute as was Iowa’sAldo Leopold Center. MISA is a joint ven-ture, a partnership, hard won after fouryears of trust building, structured dialogueand negotiation between advocates for sus-tainable agriculture and family-sized farmsand the COAFES faculty and administra-tion. It is governed by a fifteen-memberboard of directors, seven of whom must besustainable agriculture farmers. Nine mem-bers are nominated by the Sustainers, andsix are nominated by the University.

All other university programs in sus-tainable agriculture that involve citizensplace them on advisory committees, noton decision-making boards like MISA’s.The past two deans of the COAFES strug-gled with this relationship because theUniversity’s hierarchal structure doesn’toperate in terms of dialogues, collabora-tions or partnerships, especially with farm-ers or staff of non-profit organizations.However, though uncomfortable withMISA’s independence, the deans came torealize the advantages of having good rela-tionships with MISA’s constituency and itsfriends in the state legislature.

MISA’s AccomplishmentsMISA has leveraged its yearly base budgetfrom the College to bring over $8 millionto sustainable agriculture endeavors inMinnesota over the past eight years. Aboutone-fourth to one-third of the funds fromthe College were spent on a competitivegrant program for multi-disciplinaryresearch. MISA’s Program Committeemade grants to build research teams thatincluded farmers, university researchers,non-profit organization staff and agencyprofessionals. Recipients raised additionalfunds from private foundations, the USDASustainable Agriculture Research andEducation program, and the MinnesotaLegislative Commission on MinnesotaResources; thus additional dollars werefunneled back into the University forresearch and outreach.

MISA’s many other accomplishmentsinclude the establishment of a graduateminor in sustainable agriculture and a veryunconventional endowed chair in agricul-ture systems, both guided by committeesthat include representatives of the commu-nity as well as faculty. The endowed chairprogram is called a “revolving bench” by itsfounders, because two or three people can“sit” in the chair at one time. Over a threeyear period the chair has been filled witheight individuals, including two farmersand two community organizers.

Special appropriations from theMinnesota Legislature also extended MISA’sreach. In cooperation with the MinnesotaDepartment of Agriculture, MISA createdan information exchange that advises—andlearns from—farmers and the general public.Organizations in the Sustainers’ Coalitionlobbied the legislature for funds to form fiveRegional Sustainable DevelopmentPartnerships that provide rural communitiesdirect access to University resources to buildtheir economies on sustainable principles.Farmers working with the Sustainers alsoconvinced the Legislature to fund a new fac-ulty position and facilities for an AlternativeSwine Systems Program. MISA received thefunds and established an Alternative SwineSystems Task Force that included farmers as

well as faculty from the Animal ScienceDepartment. Today, swine research is goingon in hoop house structures at the WestCentral Research Station in Morris,Minnesota.

The ConflictMISA was accumulating successes andincreasing its capacity to advance sustain-able agriculture when President MarkYudolf hired a new Dean for the Collegeof Agriculture, Food and EnvironmentalSciences in 1999. Straight out of the phar-maceutical biotechnology industry, DeanCharles Muscoplat repeatedly declared thathis goal for the College was to develop andpatent a gene in soybeans that could curecancer. MISA constituents could see thathe was unfamiliar with the concepts of sus-tainable agricultural systems.

In January 2000, Dean Muscoplatannounced that all the “centers” housed inthe College would have to accept budgetcuts and undergo a faculty review to deter-mine if they should continue or be termi-nated. MISA, not a “center,” had alreadyundergone an outside review of its first fiveyears, according to its by-laws, butMuscoplat ignored this process and its rec-ommendations. Don Wyse, MISA’s execu-tive director, worked to build a good rela-tionship between MISA and DeanMuscoplat, but the new dean didn’t seem

to understand what MISA meant by sus-tainable agriculture, nor the nature ofcommunity involvement in the Institute.Although he could successfully transitionfrom the corporate boardroom to the hier-archy of university administration, he didnot fathom how to work with a partner-ship that gave decision-making powers tosmall family farmers, non-profit organiza-tion staff and faculty members on theMISA board.

In April, 1999, Muscoplat forced theresignation of Don Wyse, “because ofphilosophical differences,” without con-sulting the Board of Directors. Friends ofMISA were outraged; more calls and lettersof protest poured into the universityadministration than had ever been seen

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Continued from page 1

“Before MISA, the College wasn’t even acknowledgingsuch a thing as sustainable agriculture.”

MISA TodayThe MISA office is still open, the website(www.misa.umn.edu) is active, board meet-ings are held, students continue to holdtheir “What’s up in Sustainable Agriculture”brown bag seminars, but according to GregReynolds, a MISA board member andorganic vegetable farmer from Delano,Minnesota, “there is a feeling of beingstuck.” He thinks that the basic problem isthat MISA’s vision is not the Dean’s visionfor agriculture.

“Firing Don Wyse was not an acci-dent,”Greg told me, “but a deliberate actbased on where the College should go. The

only reason the Dean has ever given is thathe had a philosophical difference withDon.” Now the University is dragging itsfeet in settling this, because “they don’tknow how to deal with community.”

Carmen Fernholz, an organic grain andlivestock farmer from Montevideo, whochaired the MISA board from 1992 to1998, is afraid that there is a deteriorationof the friendly environment for sustainableagriculture that MISA created. “BeforeMISA, the College wasn’t even acknowledg-ing such a thing as sustainable agriculture.There were a few strong souls on the facul-ty, but they were afraid to step forward. InMISA’s peak time, the College was gettingnew staff and researchers who wanted tomake agriculture more sustainable.”

This is not to say that COAFES becamedevoted to sustainable agriculture; facultyadvocates for sustainable agriculture are stillin the minority. But MISA did attract sus-tainability-minded students and faculty tocampus. And new faculty does make a differ-ence. Carmen and I recalled a MISA boardvisit in 1995 to the Lamberton Research andOutreach Station in southwest Minnesota,where the board was shown a field of soybeansdotted profusely with cockle burrs and toldthat it was an experiment in organic produc-tion. It was pitiful, a typical example of con-ventional researchers studying a field of soy-beans with no chemical inputs, but not study-ing an organic production system.

“You wouldn’t recognize those researchplots now,” Carmen told me. With theaddition of two faculty members dedicatedto doing effective research on organic farm-ing, the station now has an entirely different

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before. The MISA Board asked the Dean tomeet with them, and he did, attended bytwo campus police officers who stood out-side the door while the board chair, SisterMary Tacheny, from the School Sisters ofNotre Dame, facilitated the meeting. DeanMuscoplat talked unconvincingly about hiscommitment to sustainable agriculture, andit was clear that he expected the board toaccept the situation and wait for a reviewby the College to learn MISA’s future. Heclaimed that MISA’s authority as laid out inthe by-laws to hire and fire an executivedirector was invalid and refused to reinstateDon Wyse.

The Sustainers felt they were almostback to square one, but they sent represen-tatives to meet with Dean Muscoplat andother administrators in May to start a dia-logue, and agreed to continue meeting togain a better understanding of each other’spositions. Now, seven months later, they arestill meeting. Muscoplat has insisted thatMISA’s unique structure “will not work,”though it was approved by the Universityadministration in 1991 and worked foreight years prior to his employment at theCollege. The MISA board refused toapprove the hiring of a new executive direc-tor, asserting that they had not dismissedDon Wyse, but did accept the appointmentof an “acting administrator,” to assumesome of Don’s responsibilities. As of thiswriting, there appears to be a proposal onthe table for a by-laws amendment settingup a joint oversight committee with equalrepresentation from the University and theBoard to handle personnel functions.

If negotiations on this proposal can pro-duce a settlement, it would be a happy firststep, but other problems remain. Last spring,MISA learned that its base funding from theUniversity could be cut significantly or com-pletely removed. Dean Muscoplat has offeredto help raise grants and contributions forMISA, but the Sustainers insist that COAFEScommit basic funds to MISA’s budget onbehalf of the public. Statements by DeanMuscoplat in reference to the management ofMISA’s grants program and the endowedchair program cause concern amongSustainers who fear he may attempt to over-ride the committee process and gain controlover how those funds are spent.

research agenda. Lamberton researchers arelooking at how to restore crop diversity tothe region, and the rotations necessary toan organic system fit their research agendawell. Carmen, who serves on the ElwellFarm Ecology Board, a research focus ofthe Lamberton Station, credits the influ-ence of Don Wyse and the friendly envi-ronment for organic agriculture that MISAcreated for the turnaround at theLamberton station.

MISA Tomorrow?What has made MISA such a vital forcehas been the involvement of a constituencyin its conception, development and gover-nance. MISA founders insisted that theorganization exist outside the mold of tra-ditional land grant college programs, andnot be guided by conventional agricultureminds. Sustainers’ Coalition members havevigilantly monitored its program grants,publications and the development ofregional partnerships so that MISA reachedout beyond the audiences land grant col-leges have come to serve and connectedwith those the land grant colleges wereestablished to serve.

MISA’s founders thought they had builtprotection into the by-laws that would pre-vent its dismantling. But a new dean washired who first disregarded the by-laws,then declared them unworkable, and hehas been backed by the UniversityPresident. However, MISA is backed by atenacious grassroots constituency. In spiteof the toll it is taking on individual organi-zations to have their executive directorsspending so much time in negotiationswith the University, the Sustainers are notgiving up. This is how MISA was created.This is how sustainable agriculture advo-cates in Minnesota will keep it alive.

To follow events as they unfold, visitwww.sustain.org/MISAfriends.

Dana Jackson is the associate director of LandStewardship Project, an 18 year oldMinnesota-based organization that fosters anethic of stewardship for farmland and pro-motes sustainable agriculture and sustainablecommunities. Dana served on MISA’s Boardof Directors from 1994 through 1999 and isstill a member of MISA’s Endowed ChairCommittee and the Graduate MinorCommittee.

“You wouldn’t recognize those research plots now.”

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will be available. Check our website formore information at www.ofrf.org, whereyou can also find information aboutbecoming a SCOAR participant.

USDA HighlightsMeanwhile, back in Washington, finalUSDA appropriations for the 2001 fiscalyear emerged with a little bit of new moneyfor organic research and education.$500,000 has been allocated for a new com-petitive grants program dedicated to “organ-ic transition.” OFRF has commented toUSDA on how the program should bedirected. The USDA-SARE program got itsfirst real increase in years, with a boost ofabout $2 million dollars to a total of about$13 million. SARE is funding a growingnumber of organic projects, and this increasein funding should help continue that trend.

Of course the overall situation at USDAwill be in turmoil as the new administra-tion takes the reins. Ann Veneman, thenew Secretary of Agriculture, has somefamiliarity with organic agriculture fromher stint as the head of California’sDepartment of Food and Agriculture. Webelieve that organic farming is basically anon-partisan phenomenon, and hope toconvince Secretary Veneman that it isimportant to nurture its further growth.

AgriculturalBiotechnology ProgramIn recent months, a major focus of ourPolicy Program has been agriculturalbiotechnology and genetic engineering. Asa member of the USDA’s AdvisoryCommittee on Agricultural Biotechnology,I have been active in representing the ques-tions and concerns of organic farmersregarding the use of genetic engineering inagriculture. We’ve partially succeeded ingetting our concerns on the table and intothe general debate, but that’s about as faras it goes. In the context of the Starlinkdebacle, where GMO corn deemed unfitfor human consumption found its wayinto numerous commercial food products,

farmers generally are getting the short endof the stick and organic growers are cer-tainly not an exception.

OFRF Board and staff are now finalizingan organizational policy statement on agri-cultural biotechnology, which will be avail-able on our website shortly. In overview,OFRF feels that genetic engineering tech-nologies may ultimately have useful poten-tial, but we have grave objections to theways in which it is being developed,employed, and regulated at present. Webelieve that conditions for the safe andeffective use of organisms modified bygenetic engineering (GMOs) for agricultur-al applications are not currently in place.This includes the inadequacy of scientificunderstanding about GMOs in the envi-ronment and the food supply, as well as theshortcomings of the U.S. government regu-latory system for these products.

OFRF believes that the profitability offarming and food security will bothimprove without genetic engineering iffarmers and researchers put much moreeffort toward developing ecologically sus-tainable systems. Therefore, the OrganicFarming Research Foundation generallyopposes the use of genetic engineering inagriculture at this time.

Policy Program Notesby Mark Lipson, Policy Program Director

New Organic ConsortiumAs we reported in the last issue of theInformation Bulletin, OFRF’s ScientificCongress on Organic Agricultural Research(SCOAR) has received funding from theUSDA’s Initiative for Future Agricultureand Food Systems (IFAFS) as part of a con-sortium with Ohio State, Iowa State, NorthCarolina State and Tufts Universities. This“Organic Agriculture Consortium” isanother “first” in the progression of newinstitutional attention to the needs oforganic growers.

The $1.8 million awarded for the multi-year Consortium is certainly the largest sin-gle grant award ever made for organicresearch and education. It’s also the firsttime that multiple land-grant universitieshave collaborated on a set of organic proj-ects, and it is the first significant federalgrant money that OFRF has pursued forour own work. OFRF’s portion of theConsortium proposal was funded at$220,000 over two years for activities ofthe SCOAR project. These funds will sup-port OFRF staff time and pay for farmersto travel to SCOAR meetings.

Inaugural SCOAR MeetingSCOAR is a nationwide effort to stimulatescientific dialogue about organic agricultureamong working organic farmers, researchscientists, and agriculture information pro-fessionals. Its mission is: to plan and pro-mote research and information exchange forunderstanding and improving organic agri-cultural systems.

On January 23 and 24, OFRF will hostthe first national SCOAR meeting at theAsilomar conference center in PacificGrove, CA. This meeting will be an oppor-tunity for over 100 producers, researchers,and information-management professionalsfrom around the country to come togetherand share their experiences about on-farmorganic research. Meeting participants willrefine SCOAR’s objectives and begin devel-oping a national agenda for organic farm-ing research. A transcript of the meeting

Another flash update on...

These Exciting Times in Organic Research Policy

ACTION ALERT!

The USDA has released a request for public

comments as a part of its biotechnology ini-

tiative. The request can be found in the

Federal Register, November 30, 2000,

p.71272-71273, and the deadline for com-

ments is February 28, 2001. The request is

on the subject of marketing of genetically

engineered food products, as well as the

related issues of product segregation and

identity preservation. This is in advance of

any rulemaking and offers an opportunity to

let the USDA know what issues are of con-

cern to the public and the agricultural indus-

try. This is a very important occasion for the

organic farming sector to voice its opinions

about how the USDA should proceed with

the regulation and marketing of GMOs in

the foodchain. Please see the OFRF website

at http://www.ofrf.org/policy/index.html for

more information about this request for

comments.

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W I N T E R 2 0 0 1 N U M B E R 9

Three years ago, OFRF PolicyProgram Director Mark Lipsonpublished a groundbreaking study,

Searching for the O-Word, which scouredUSDA research projects for those relevantto organic producers. Of 34,000 projects,the study found only 34 that had “strong”relevance for organic producers, or 0.1%(one-tenth of one percent).

This past year, I’ve been doing a follow-up study, identifying specific organicresearch projects and information sourcesat land grant institutions across the coun-try. I’ve considered calling it “Needle in aHaystack,” since the information is sosparse and dispersed. I have found thatonly 131out of 885,800 total research acresare certified organic and being used fororganic farming research. This works out to0.01%, or one-hundredth of one percent,of the total. Another 206 organic researchacres are not certified, and 239 acres are intransition to certified status.

There are notable organic research pro-grams at the land grant level inMinnesota, Iowa, Ohio, North Carolina,and West Virginia. Many of these pro-grams are taking a systems approach,involving growers at the decision makinglevel and using interdisciplinary researchteams. Here are some details:

University of MinnesotaSt. Paul, Minnesota

Eighty acres of the Elwell AgroecologyFarm are certified organic. Elwell is partof the Southwest Research and OutreachCenter in Lamberton (noted in our fea-ture article). Organic rotation plots wereestablished in 1990 and a comparisonstudy has been done since 1989.Researchers Elizabeth Dyck and PaulPorter are also managing the OrganicConversion Project that works to connectfarmers converting to organic with men-tors and simultaneously collect data onthe conversion process.

North Carolina State UniversityRaleigh, North Carolina

The Organic Unit within the Center forEnvironmental Farming Systems (CEFS)had 80 acres certified prior to being flood-ed by two hurricanes in three years. Theproject has been moved to higher groundand organic certification is pending for100 acres on a research station inGoldsboro. Numerous interdisciplinaryresearch projects are being done, includinga significant transition study that is com-paring six organic transition strategies.Long-term cropping systems studies arealso being established. According toresearcher Nancy Creamer, plans are toconduct comparative systems research “for

perpetuity.” An advisory committee thatincludes farmers oversees the research. A 7-acre demonstration organic farm has beenestablished at which an intensive summerinternship program was held for the firsttime in the summer of 2000.

Ohio State UniversityColumbus, Ohio

A multi-disciplinary long-term study onthe transition to organic was started in2000. After the transition period, thestudy area will be devoted to purely organ-ic research. Thirty-five acres of the 164-acre West Badger Farm in Wooster are des-ignated transitional to organic in fieldcrops. Five acres will be used for organicvegetable research at Fry Farm. Nine acreswill be certified organic. Project coordina-tor Deb Stinner has planned trials with themarket in mind. There were nine studiesin the ground in 2000, the major effortbeing a large-scale transition study. Anadvisory group comprised of growers andresearchers makes budgeting, research pri-ority, and research design decisions.

Iowa State UniversityAmes, Iowa

Kathleen Delate, assistant professor inorganic agriculture/horticulture, holds thevery first academic appointment in theU.S. specifically to study organic practices.Delate maintains designated organicresearch sites at 5 research farms andintends to certify all sites (one became cer-tified organic in 2000). Delate has 13 trialscurrently, including a project comparingthe agroecology and economics of organicand conventional corn, soybeans, oats, bar-ley, alfalfa, red clover, green peppers, broc-coli, and medicinal herb production.Farmers assist in setting research prioritiesthrough focus groups and annual meetings.

West Virginia UniversityMorgantown, West Virginia

The 60-acre Horticulture Farm has the dis-tinction of being the only research station inthe United States being transitioned entirelyto organic. An interdisciplinary transitionstudy began in fall 1999, when the entirefarm started to be managed organically. Amajor transition study is being done as wellas work on apples, pears, grapes, and blue-berries. According to director James Kotcon,the ultimate goal is to maintain the farm asan organic research farm. Advised by a com-mitte of organic growers, researchers arecomparing the organic transition in both amarket garden and field crop/livestock farm.The crop/livestock farm will also comparepresence and absence of animals in the sys-tem.

The full report covers organic farmingresearch activities in all 50 states. State ofthe States: Organic Farming SystemsResearch at Land Grants 2000-2001, isavailable for a requested donation of $5 orfree through the OFRF websitewww.ofrf.org.

Technical Program Notesby Jane Sooby, Technical Program Coordinator

Needle in a HaystackSearching for organic farming research at land grants

Though certified organic acreage represents only a tinyfragment of the total research area, the organic-dedicatedprograms that do exist are fascinating and inspiring.

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I N F O R M A T I O N B U L L E T I N

In this issue of the Information Bulletin wepresent the results of two compost tearesearch projects. The first, by RichardMerrill, looks at designing and operatingan aerated or “active” compost tea appara-tus. The second, by Sylvia Welke, field testsa variety of compost tea extracts, producedby “passive” methods, which generate a lessoxygenated tea mix. These reports helpillustrate that there are many differentopinions out there about compost teas:how they should be made, which varietiesto produce for which crops and for variousintended outcomes—such as disease sup-pression or a source of plant nutrients—and how effective teas are in the field.

To tea or not to teaAnecdotal evidence suggests that not a lotof growers—organic or otherwise—are uti-lizing teas. Producing teas on a fieldscale—especially “aerated” teas—canrequire a significant initial investment(depending on how you go about it), butperhaps more important, a commitment todeveloping a reliable protocol and methodof making observations. Key monitoringtools, such as pH and CO2 meters and a

thermometer can help, but a relationshipwith a good laboratory and a microbiolo-gist might be needed to (begin to) makesense of the outcomes.

Nonetheless, compost teas are beingexplored enthusiastically by a number offarmers and researchers, who—you guessedit—have a variety of opinions about pro-ducing and using them. Carl Rosato, anorchardist in the Sierra foothills, is devot-ing significant time and resources to teason his farm, and at this point is committedto aerated teas. (His early tea research wasreported in Information Bulletin 1:Controlling Peach Brown Rot.) Yet hefinds his research ideas and methods devel-oping slowly as he figures things out alongthe way. For example, his trials attemptingto control brown rot with teas were incon-clusive, yet he feels he can “definitely” pro-duce a nutritive effect in his peach orchardsusing a compost tea soil drench. He thinkshe has successfully made peaches sweeterwith a tea drench complemented with sul-fur and potassium. While the additives

may have produced the greater effect, henotes that he is also getting good K in thecompost feedstock he uses.

Others who have experimented with teashave found their efficacy difficult to deter-mine. Helen Atthowe, OFRF Board member,farmer and Extension Advisor in Montana,eagerly pursued tea research following publi-cation of the first German tea studies(Weltzien et al., refer to project bibliographiesin Research Reviews). Not having consistentluck with them, she focuses now on suppres-sive compost explorations. In reviewing con-tent for this newsletter, she noted that the lit-erature cited regarding disease suppressiveeffects of compost is controversial, and maybe related to initial compost ingredients. Theliterature regarding disease suppressive effectsof compost teas is even more controversial.Further, studies that document the nutritiveeffects of teas are not shown and to herknowledge have not been done sufficiently toallow prediction about what kinds of nutri-ents we can expect from compost teas madewith different materials.

To air or not to airA quiet “controversy” persists over whethercompost teas should be produced “passive-ly” (without active aeration), or “actively,”a process which might include a bubbler, avortex nozzle, or any recirculation methodthat moves the water through the compostfeedstock. Others feel the aerated/non-aer-ated issue is overstated, and may not be asimportant as other factors.

Elaine Ingham, a tea researcher with SoilFoodweb, Inc. in Corvallis, Oregon, stronglysupports the aerated approach, noting thatpassive systems can go anaerobic quickly andthat anaerobic organisms are toxic to plantcells. At the same time, she notes that justbecause a system is “passive” does not meanthat it will become anaerobic—it depends alot on the feedstock, the environment andthe brew time. However, she strongly suggeststhat anaerobic teas are not as helpful aerobicones—that anaerobic by-products producecompounds that are toxic to plant cells, andthese conditions should be avoided. She sup-ports a recirculation or vortex system, becausesuch active systems push the beneficialmicrobes out of the feedstock and into the

tea substrate. Ingham believes this action isimportant to pull the organisms out of thesolution, although not too forcefully orthey will be macerated. Otherwise the teawill contain only the non-living nutrientand miss the desired bacteria and fungi.

However, a number of studies andresearchers suggest that anaerobic teas mayhave greater disease suppressive capabili-ties—possibly due to the biocidal effects ofthe unpleasant by-products they create, orbecause the desired beneficial organisms arepresent in the extracts. Sylvia Welke inves-tigated the potential for disease suppressionof an” anaerobic” tea based on WillBrinton’s (Woods End Laboratory, Mt.Vernon, ME) suggested protocol for mak-ing a tea without active aeration, otherthan occasional stirring.

Will Brinton finds the discussion of aero-bic teas vs. anaerobic teas problematic. Hebelieves that neither method represents a sil-ver bullet; that nature is not that simplistic.Studies have shown that facultative anaer-obes are the bacteria doing the work of dis-ease suppression, yet by definition, they maylive in aerobic or anaerobic conditions, andhave the ability to survive in low-oxygenenvironments. Standing, unaerated solutionshave been shown to have extremely highcounts of facultative anaerobes.

Taking the plungeBrinton suggests that for those who wantto try teas for disease suppression, to firstidentify the disease you’re trying to controland conduct a thorough review of the liter-ature. Has the organism you’re seeking tocontrol ever been successfully controlledusing teas, and if so, what was done? If yousend a sample of your tea to a lab foranalysis, look at bacteria counts and themix of organisms, and check whether thoseorganisms have been shown as effectiveagainst your disease. And realize, too, thatweather and environmental conditions willaffect the efficacy of a tea. A tea that per-forms well under one set of conditions maynot be as effective when those conditionschange.

Don’t be afraid to experiment with com-post teas. But rather than look for simpleexplanations, be open minded to the vari-ety of possibilities, and as Brinton says,“review all of the literature and the contra-dictions, and embrace that.”—EW

In Context

Compost Teas: A Brave New World

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Interest in organic teas for use in agri-culture and horticulture has grownrapidly during the last decade. The lit-

erature and internet web sites are full ofexperiments, testimonials and observationswhich suggest that certain liquid extrac-tions of manures or composts, at variousstages of decay, can supply plants with atleast four major benefits: a source of plantnutrients; a source of beneficial organiccompounds, an ability to suppress certainplant diseases; and as a way to build soilstructure when applied as a drench.

In preparing for this project wereviewed some of the pertinent researchconcerning organic teas, and noted thatthe results of studies on the effects of suchteas, especially as a biocide, is quite mixed.We believe this is due to the variablenature of both the organic feed stock andthe methods of extraction. We make somesuggestions concerning a protocol for on-site research into the production and useof organic teas with suggestions for con-trolling feedstock and extractor variablesin field experiments. Finally, we describeour experiences with a simply-made, aero-bic organic-tea extractor prototype. Ourresults confirm those of others: so-calledanaerobic tea systems—those in whichorganic stock is simply soaked in water—are actually aerobic for the first 48 hoursor so of extraction. After that, theybecome anaerobic. In other words, aerated

or aerobic systems simply extend the timeof useful extraction by replacing or addingoxygen into a system that would otherwisego anaerobic. It should be the goal of allorganic tea extraction methods to avoidanaerobic conditions.

Project Objectives■ To test the design and operation con-

sistency of an organic tea apparatusin search of an inexpensive extractordesign prototype that will produceexpected microbial populations.

■ To sample, test for, and document anyshort-term differences between aerobicand anaerobic teas in the CabrilloOrganic Tea Apparatus (COTA) exper-iment and the compost feedstock.

■ To establish some experimental proto-cols for future projects that will furtherdefine what is being produced in aero-bically-made organic teas.

MethodsCompost source. We located a consistentsupply of near-finished compost made byGrover Environmental Products inModesto, California, a commercial com-post producer registered with theCalifornia Compost Quality Council. Thecompost is made from vegetable producewaste from supermarkets, city green wastecollection programs and materials fromtheir own landscaping business. Materialsare screened, piled in rows and processedusing a modified Lubke method. Theyhave designed their own row-turningequipment that measures moisture con-tent and adds water as needed while turn-ing rows. Rows are monitored daily foroxygen, ammonia, pH, and temperature,which does not exceed 145 degrees F.Every 3000 yards of compost is checkedfor heavy metal content and ammoniacontent as regulated by the state wastemanagement board.

Set-up. The experiment was performed inan empty greenhouse so that we couldcontrol the external temperature and envi-ronment for all of the individual tea appa-ratuses. Four aerobic tea apparatuses werebuilt following the plans of “Model 3,” adesign that incorporated spray-head andscreening improvements over earlier trialmodels. In addition, four anaerobic barrelswere designed to be used alongside theaerobic apparatuses. These anaerobic bar-rels consisted of the same type of plastic,fifty-five gallon barrels used for the aero-bic units. Shade cloth sacks were sewn tohold the same amount of compost as theaerobic apparatuses. These sacks were sus-pended in the middle of the barrels usinga length of line and a metal bar.

Preparation. Two 55-gallon barrels werefilled by taking shovels of compost fromall sides of compost piles, and at differentheights and depths. These barrels werethen taken to the project site. All barrelswere filled with 50 gallons of water runthrough a garden dechlorinator to reducechlorine content. Five gallons of compostwere added to every apparatus, in thefeedstock container for the aerobic barrels(#1-4), and in shadecloth bags for theanaerobic barrels (#5-8).

Richard Merrill and John McKeon

Apparatus Design andExperimental Protocol for Organic Compost Teas

Project leader:Richard Merrill, Program Director, Dept. ofHorticulture, Cabrillo Community CollegeSoquel, California

Student assistants:John McKeon, David Seidman, KayHoberecht

Experimental design support& data analysis:Marc Buchanan, Agricultural Consultant

Cooperating growers:Route One Farms, Santa Cruz

OFRF support: $4,860

Project period: 1997-1998

The Cabrillo Organic Tea Project double-barrel active tea extractor units #1-4, set upin the greenhouse. The four passive extractors(#5-8) were single-barrel units (not shown).

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Baseline compost data. At the same time,samples of compost were collected fromthe feedstock containers of barrels #1-4.These were sent to BBC Labs in Tempe,Arizona for analysis to serve as a compari-son to the tea samples collected later at24- and 48-hour processing times.

Tea production and sampling. At 4:00pm on June 21 the four aerobic barrelswere turned on and the shadecloth bags ofcompost were put in the anaerobic barrels.Data collection began immediately. Everytwo hours, excluding the hours from 12am to 8 am, we measured oxygen (O2),pH, electrical conductivity (EC), and tem-perature. Oxygen measurements weretaken with a portable O2 meter to measurethe differences in O2 levels between theaerobic and anaerobic production meth-ods. These measurements were taken with-in the barrels at a middle depth for theaerobic barrels and at a surface depth andbottom depth in the anaerobic barrels.Electrical conductivity, pH and tempera-ture were taken with portable meters aswell. Samples were extracted from eachbarrel and tested in a cup. These measure-ments were taken to establish any trendsduring production. At the 24-hour mark,tea samples were taken from all eight ofthe barrels and sent to BBC Labs for com-post tea analysis.

Tea additive tests. After the 24-hour sam-ples were taken, 32 oz of sulfured molassesand 32 oz of azomite rockpowder wereadded to aerobic barrels #1-4. These sup-plements were added as a food source formicrobes that might exist in the tea to seeif there would be any population increasein the groups tested for by BBC Labs inthe 48-hour sample.

Anaerobic tank mixing. Also at the 24-hour mark, anaerobic barrels #5-8 weremixed vigorously for one minute and thiswas repeated every four hours up to the48-hour mark. This was done to docu-ment any trends in the difference betweenthe active and passive approaches to anaer-obic tea production.

All measurements were continued untilthe 48-hour mark, at which point tea sam-ples were taken from barrels #1-4 and sentto BBC Labs for compost tea analysis. At

this point the physical experiment wascompleted.

Results■ There were minor differences in micro-

bial populations as indicated by bio-plate counts between the sub-samplesof compost taken from the same batch.

■ There was no significant difference inO2 between passive and active treat-

ments over the first 24-hour period.

■ There was no significant difference inmicrobial populations as indicated bybio-plate counts between passive andactive treatments after the first 24hours, but there was a significant dif-ference after the first 48 hours in activesystems.

DiscussionOur experiments confirm those of othersthat so-called anaerobic tea systems—thosein which organic stock is simply soaked inwater—are actually aerobic for the first 48hours or so of soaking. In other words,“aerobic” systems are merely extending thetime of useful extraction by putting moreoxygen into the system.

If suppressive microbes tend to be foundmore in older teas (several days) thanyounger ones (1-2 days), it is possible thatthe organic matter being extracted is,itself, undergoing decomposition in acomplex aerobic/anaerobic environmentwithin the slurry, i.e., maybe the extratime needed to extract microbes is reallyjust more time to give the feedstock timeenough to decompose to the appropriatemicrobial substrate.

Field test of the Cabrillo OrganicTea ApparatusThe COTA was field tested by farmers atRoute One Farms, Santa Cruz, CA. Theircritiques are as follows:

❖The capacity of the machine was notlarge enough for field use. Given this limi-tation they adopted it for use on green-house seedlings. However, they modifiedthe bottom barrel by enlarging it to a con-tainer that can hold up to 250 gallons andare planning to use teas in the field at a50% dilution.

Defining Organic TeaExtraction SystemsOrganic tea systems have been describedas either anaerobic or aerobic dependingon the degree of aeration given to the sys-tem. This is somewhat misleading. Thedistinction is the degree of aeration givento the system in order to allow it toextract over a protracted time period. Weprefer the terms passive (a contained orbagged slurry that is simply allowed tosoak in water) and active or aerated (anorganic tea system that receives a boost ofoxygen with the use of mechanical mix-ing, packed columns or forced air.)

Passive tea extraction systems are thosein which a feedstock is simply left to soakin water. After a few days, passive systemswill become anaerobic and, as a result,begin to produce various organic acidssuch as butyric, proprionic and aceticplus the odors of reduced forms of nitro-gen (NH4) and sulfur (H2S) which inturn will attract flies. There is some evi-dence that the by-products of anaerobicdecay can actually harm plant roots(James Downer, pers. comm.).

The trouble with passive extractionmethods is that they can go anaerobicvery quickly. When you soak organicmaterials in water for more than a fewdays, aerobic microbes in the slurry pullall the oxygen out of the water. Thisturns over the production of the tea tooxygen-avoiding (anaerobic) microbes,which produce an inferior tea with feweravailable nutrients and organic acidsharmful to plant growth. Our researchindicates that there is usually enough dis-solved oxygen in clean water so thatanaerobic microbes aren't dominant forat least 24-48 hours under most condi-tions. After that, the quality of the teabegins to deteriorate. All types of tea sys-tems should be aerobic. The major vari-able is the length of time that aerobicextraction is allowed to take place.

There is evidence that adding oxygento an organic tea slurry improves thequality of the extracted tea. This seemsto be because aeration extends the extrac-tion time, which allows the removal ofbeneficial organic compounds like vita-mins, enzymes, organic chelators plus abevy of beneficial microbes. —RM & JM

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❖The top barrel is extremely heavy afterproducing tea due to saturated compost.Removing and replacing the compost takesmore than one person.

❖The feedstock container was too difficultto use given its placement inside the topbarrel. They replaced it with a plastic con-tainer the goes all the way to the top ofthe barrel and although still heavy, easierto deal with.

❖ Screening and sprayhead clogging is aproblem with fine sized compost.

Suggestions for afield experiment protocolHaving reviewed over 100 papers onorganic teas, we are unable to reach a con-clusion as to the value or efficacy of organ-ic teas. The problem, as we see it, has beena lack of standard protocol for organic teaexperiments. A protocol is importantbecause of three major sources of varia-tion: 1) the organic feedstock, 2) themethod of extraction, and 3) the timeinterval of extraction.

The most difficult variable to control isthe feedstock, whether it is fresh manureor suppressive compost. A consistentsource of feedstock should be found andsub-samples taken from the same batch. Ifpossible, inorganic nutrient and bioassaytests should be done on pilot sub-samplesto establish the degree of variation withinthe feedstock.

The method of extraction is a functionof the type of extractor used, and the con-ditions under which the experiment takesplace. Replications should be assigned toextractors of similar design and aerationunits. Since multiple replications are so

important to a welldesigned experiment,it is important to finda well functioning yetinexpensive extractordesign such as the onedescribed in thisreport. Experimentersshould also control forthe following environ-mental variables: 1)the temperature ofextraction; 2) theamount of ambientlight; 3) the chemical

quality of the water used in extraction;and 4) the use of supplemental ingredi-ents.

The temperature of extraction & ambi-ent light. The organic tea apparatuses atCabrillo College were maintained outsideand under a shade structure. Tea produc-tion rates varied greatly with the swings indaily and seasonal temperatures. AtCabrillo College, ambient temperaturesvary from daytime highs in the upper 70’s(August-November) to nighttime lows inthe lower 30’s (December-February). Ourobservations indicate that below 45-50°F .extraction was noticeably slowed down.Most nutrients tend to be more soluble inwarmer water, and because microbial respi-ration rates are proportional to ambienttemperature, heating the slurry or keepingthe extractors in heated spaces might havesome merit in cool locations.

Chemical quality of the water. Thechemical properties of the water beingused can strongly affect the quality of teaproduced. Acid and alkaline water with lit-tle buffering capacity can keep certainmicrobes from flourishing. Excess salts cando the same thing. When possible, try touse filtered, spring or rain water, whichwill produce a richer tea.

Supplements to feedstock. Severalresearchers and practitioners have recom-mended the addition of concentrated supple-mental nutrients to increase microbial activi-ty in organic teas. These include sugars,unsulfured molasses (at a rate of 1 tbsp ofmolasses per 5 gals of water), rock fertilizers,kelp and fish products and barley malt. Wewould only add the possibility of addingcommercial microbial cultures to jump-startmicrobial activity in organic teas.

The time of extraction. The time of teaextraction strongly affects the quality andcomposition of organic teas. According toAmigo Cantisano53 “Teas for nutrient andhumic acid extraction are ready in 1-2days...some disease suppression is notedfrom these young teas; more time isrequired for maximum disease suppressiveteas.”

An efficient organic tea experimentshould focus on a minimum number ofvariables at a time because of the inherentvariability of the testing situation.

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Design and Construction Detailsof the Cabrillo Organic Tea ApparatusThe overall design of the Cabrillo Organic Tea Apparatus is simple, inexpensive (total cost:$303), and uses readily available parts. What follows are step by step instructions for buildingthe apparatus, completing assembly of six individual components, which make up the entireextractor unit.These components are:

• The Containers• The Packed Column• The Pump Assembly• The Spray Head• The Feedstock Container• Miscellaneous Parts

The order of assembly is important since completion of one component leads to the placementand sizing of the next. [All required materials and number of units needed (#) are shown in bold-face, followed by an estimated cost ($); required tools are shown as underlined.]

The Containers (Fig. 6)(2) 55 gallon plastic barrels (cost: $100). Cut the tops off both barrels: Drill with ½” bit a

½” hole on the top of each barrel on the inside of the lip. Insert the scroll saw and cut aroundthe circumference of the barrel to remove the top.

Cut a hole in the bottom of the top barrel to-be: Draw a 10”x 7” diamond shape using a per-manent marker. Using the scroll saw, follow your markings to remove the diamond.

(1) Automobile tire inner tube (cost $10). Use a utility knife to cut a piece of the inner tube(one layer thick) so that it extends 1” beyond the edges of the diamond. Measure and cut a slitlengthwise in the middle of the piece of inner tube 3½” long. Inside the barrel, sand the insideedges of the diamond as well as the edges of the inner tube with 80 grit sand paper. Applywaterproof silicone sealant to the sanded areas and glue the inner tube to the inside of the bar-rel. This creates a funnel which prevents the tea from leaking out the sides of the bottom of thebarrel. It also reduces the splash and loss of tea as it falls between the barrels.

The Pump Assembly (Fig. 7)(1) ¼ hp submersible pump w/ auto float switch ($80). Check the size of your sub-

mersible pump line out. Make sure you have the right fitting to adjust the pipe size to ½”.(1) 20’ section of ½” PVC pipe ($12). Cut a 1’8” piece of the ½” PVC pipe. Glue the line

out fitting to the pipe and attach it to the pump. Place the assembled pieces inside the bottombarrel. Cut a 1’10” piece of the ½” PVC pipe.

(8) 45 degree ½” PVC elbows ($7). Wet/dry PVC cement. Glue a ½” 45 degree PVC elbowat each end of the 1’10” pipe. Make the 45 degree angles opposite each other, one facing downto the pump and the other facing up towards the top barrel. Glue into place on the assembledpieces inside the barrel. Place (2) 2’ lengths of 4x4” lumber ($5) spacers on the top of the bot-tom barrel. Place the top barrel on the spacers.

Adjust the pump assembly so that the top of it extends out the back of the bottom barrel.Measure the distance from the top of the pump assembly to the top of the top barrel and cut apiece of PVC pipe to size. Glue into pump assembly.

(9) 1/2” 90 degree PVC elbows ($7). Glue a 3” piece of ½” PVC pipe into a 90 degreeelbow. Slip (1) ½” ID (inside diameter) piece of clear poly hose ($1) over the ½” PVC pieceand secure with the second available ½” hose clamp. This will connect to the spray head andserve as a visible flow check. Glue a ½” 90-degree PVC elbow on the top end of the pumpassembly.

The Packed Column (Fig. 8)(1) 4” dia. PVC pipe, 2’6” long ($15). Place the PVC pipe inside the top barrel. Bring the

top of the pipe 2” from the top of the barrel and hold it there. On the outside of the barrel,with a tape measure, measure down 5” from the top of the barrel. Take the drill with the ¼” bit

Figs. 6-10 (this and the followingpage): Details of active compost teaapparatus.

Fig. 6. Double-barrel active tea

extractor showing outline of 55-

gallon plastic barrels, pump

assembly and wooden spacers

between upper and lower barrels.

Fig. 7. Pump

assembly, side view.

Fig. 8. Packed column filled with

4 inch PVC pieces, bolted inside of

top barrel; a gravity-fed aeration

system.

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Benefits of organic teas:A review of the researchliterature

Teas Provide Inorganic Nutrients andBeneficial Organic CompoundsThe types and amount of nutrients in anorganic tea depend on the age and kind ofmaterial used. The nutrients from freshmanure teas tend to be soluble salts, espe-cially macronutrient (N, P, K, Ca, Mg andS) plus micronutrients (e.g., Fe, Zn, Mnand Cu).

Nutrients from more decomposed feed-stocks such as young or unstable compostcontains some available nutrients not yetfixed in microbial biomass, but they alsoprovide organic nutrients like sugars andamino acids, plus organic chelating agents(humic and fulvic acids) that carry extract-ed micronutrients (e.g, iron, zinc, man-ganese and copper) to plants. Sincemicronutrients are the building blocks ofplant enzymes, vitamins and hormones,organic teas can also increase a plant’s dis-ease resistance, vigor and hardiness by pro-viding both micronutrients and the organ-ic chelating agents that make them avail-able. Organic teas also contain long-chaincarbon molecules which provide carbonand oxygen for soil microbes, includingmycorrhiza. The mycorrhizal hyphae, inturn, greatly extend the root systems ofplants, increasing their nutrient uptake,respiration, tolerance to weather extremesand possibly conferring some diseaseresistance.

Teas Suppress Certain Plant DiseasesIt has been shown that certain soilmicrobes have the capacity to suppressmany serious plant diseases1,2. The dis-ease-suppressive characteristics of organictea was reported as early as 1973 by Huntet al3.

Extractions from well-aged and suppres-sive composts have few soluble nutrients,but they do contain organic chelators andpopulations of various biofungicidalmicrobes. These teas have been shown toact as a natural fungicide, i.e., as an inocu-lum of microorganisms that can competewith and suppress some plant pathogens,especially foliar-fungal diseases.

and drill though the barrel and the pipe. Remove the pipe and measure down 2’ from thefirst ¼” hole on the barrel. Drill a second hole though the barrel. Measure 2’ down fromthe first hole on the pipe and drill a second ¼” hole.

Take a 5”x 5” piece of chicken wire and cover the bottom end of the 4” pipe. Fold thechicken wire around the outside of the pipe and slide (1) 4½” threaded hose clamp ($3)over the wire. Secure the wire to the pipe by threading down the clamp. This serves tokeep the 1” PVC pieces inside the packed column. (1) 10’ length of 1” PVC pipe ($6)cut into 1” sections with PVC pipe cutters or hack saw. Attach the Packed Column to theinside of the barrel using (2) ¼”x 2” carriage bolts, (4) ¼” washers and (2) ¼”wingnuts. Fill the column with the PVC pieces to within 1” of the top.

The Spray Head (Fig. 9)(3) ½” PVC tees ($3), (3) ½” PVC slip-fit ball valves ($18), (1) ½” PVC cross ($2),

(4) ½” PVC end caps ($1). Individually assemble the top, connector, and bottom piecesof the spray head and then glue the three pieces together. The connector piece should belined up directly underneath the line above it, so that it is running back towards the cross-piece. Attach the bottom piece to the connector piece so that the spray lines parallel theconnector piece. Check the spray head assembly for fit in the top barrel. (2) ½” hoseclamps ($3). Connect the spray head to the pump assembly and secure using a ½” hoseclamp. Stabilize the spray head by placing a yardstick across the top of the barrel andunder the top piece of the spray head.

The Feedstock Container (Fig. 10)Cut a 4’ diameter circle from (1) 4’ x 4’ piece of shade cloth ($4). Assemble feedstock

container ring. Refer to diagram for feedstock container ring assembly, using the 1/2”PVC straight piece sections and 45- and 90-degree PVC elbows. Place shade cloth insidering so that there is a 1” to 2” margin around the outside.

Use zip-ties (1 package $7) every 1½” to fasten the shade cloth around the ring. Use(2) 10” S-hooks ($2) (bought or easily made from 14-gauge wire) to hang inside the topbarrel. Note: the inverted side of the ring should fit around the packed column.

Miscellaneous PartsThe Barrel Spacers. On the two 2’ lengths of 4x4 lumber, measure in from each side 9”.

(8) 2” C-clamps ($3). Center two C-clamps at the 9” marks and nail into place. Leave a1” gap between the C-clamps. These will serve to hold two screens in place. (2) windowscreen kits ($12).

The Barrel Spacer Screens. Assemble two 12”xl2” screens using a window screen kit orfrom existing materials. These serve to screen compost particles from the tea and keepcompost from settling in the bottom barrel. With two screens, one can be cleaned easily.

Continued on next page

Fig. 9. Spray head assembly, showingtop (above barrel), bottom (inside bar-rel) and connecting (middle)sections.

Fig. 10. Feedstock con-tainer, with PVC ringmade from elbow andstraight pieces, andporous bag assemblyfrom shadecloth.

14

I N F O R M A T I O N B U L L E T I N

ReferencesA key feature of this project report is an exten-sive bibliography of the research conducted oncompost teas. A majority of these references areprovided here; the full bibliography providedwith this report (88 references, total) may beobtained by contacting OFRF or by visitingour website: www.ofrf.org.

4 Weltzien HC. The effects of compost extracts onplant health. In: Global Perspective on SoilAgricultural Systems; 1986;2:551-553.

5 Weltzien HC. The Effects of Composted OrganicMaterials on Plant Health. In: Agriculture,Ecosystems and Enviromment; 1989 27:439-446.

6 Spring DE (et al). Suppression of the apple collarrot pathogen in composted hardwoood bark.Phytopath. 1980; 70: 1209- 1212.

1 Adams PB. The potential of mycoparasites for bio-logical control of plant diseases. Ann. Rev. ofPhytopath. 1990 28:59-77.

2 Cook RJ, Baker KF. The Nature and Practice ofBiological Control of Plant Pathogens. St. Paul,MN: Amer. Phytopath. Soc. 1983.

3 Hunt P, Smart C, Eno C. Sting Nematode,Belonolaimus logicaudatus, immobility induced byextracts of composted municipal refuse. Jour.Nematol.,1973;5:6063.

At the University of Bonn, Germany,Heinrich Weltzien pioneered research in“water extracts of compost.” He showed4

that organic tea can be used as a foliar sprayto inhibit Phytophthora on tomatoes andpotatoes. Weltzien also showed that the sup-pressive effect of organic teas are of a livingmicrobial nature. Sterilized or micron fil-tered tea had little ability to impactpathogens5. He also documented that plantstreated with tea appeared healthier and morevigorous than other plants.

Using organic teas or special compostextracts, other researchers and growers havereported modest to major control of severalplant diseases with organic teas including:Apple Collar Rot6, Apple Scab7, Botrytis orGrey Mold8,9, Downy Mildew10,Fusarium11, Phytophthora12,13, PotatoBlight14, Powdery Mildew or Erysiphe15,Pythium14,16,17,18,19 and Rhizoctonia19,20.According to these authors, compost teascoat plant surfaces (foliar application) orroots (liquid drench application) with livingmicroorganisms and provide food for benefi-cial microbes. This helps secure a diverseand healthy food web community wheresymbiotic bacteria and fungi help providedisease resistance.

In addition, several types of organic feed-stocks have produced favorable suppressiveresults including composts 5,11,21,22,23,24,

25,26,27, municipal and agricultural wastes28

and various types of lignous materials suchas wood wastes and peat moss6,12,17,18,20,29

,30,31,32,33,34,35,36,37,38.The principle suppressive microbes in

compost teas can suppress diseases in severalways39:• They induce resistance against pathogens(pre and post-infection).• They produce chemical inhibitors asreported for the suppression of Phytophthoraroot rot in media amended with hardwoodbark12,31.• They inhibit pathogen spore germination.

• They antagonize and compete withpathogens through the antibiotic effects ofparasitism, hyperparastism and nutrientcompetition. Some microbes, especially bac-teria, produce antibiotics which cover thesurface of the crop and thus prevent infec-tion by the pathogen.• They extend the root system of plants,and thereby improve nutrient uptake, plusincreased food storage and soil respiration.

There is also growing evidence that chemi-cals called siderophores, pseudobactins andpseudomycins produced by the bacteriaPseudomonas spp. exert a powerful suppres-sive effect on other organisms40. Kai et al.33

found that ten proteins from secondarymetabolites of plant or microbial origineffectively suppressed certain pathogenicfungi. In some cases, cyanids and antibioticsinteract with the host plant and create resist-ance to disease.

It’s not always clear which of these effectsis most important to a general impression of“disease-suppression” as noted in the litera-ture. Furthermore, not all such experimentshave been favorable. Using aerated Luebkecompost tea, made in a lab extractor with avortex nozzle for aeration, Wittig41 reportedthat aerobic compost tea was not effective incontrolling apple or pear scab, downymildews, brown fruit rot or peach leaf curl.He generally rejected them as effective con-trols for “foliar diseases of fruit trees andgrapes.” Wittig goes on to note:“Considering that the microorganisms pres-ent in compost may be better adapted to asoil environment, perhaps there is greaterpotential for its use as a drench in control-ling soil-borne pathogens.”

In spite of the mixed results, there seemslittle doubt that certain beneficial microbescan be water-extracted from aerated organicslurries and applied to leaf surfaces (via foliarfeeding) and/ or root systems (via drenchingor fertigation). These “beneficial” microbesinclude mycoparasites42, rhizospherecolonies43, hyperparasitic fungi40,44,45,46,

epiphytic microbes47,48 as well as specificbacteria such as Pseudomonas49,Azotobacter50, and certain fungi likeTrichoderma and Gliocladium51,52.Apparently disease suppressive microbes thathave been extracted from the compost areable to colonize the surface and roots ofplants when applied properly. Organic teassimply concentrate these beneficial microbesand allow the grower to apply them in aconvenient, concentrated form for nutrients,resistance and disease control53. In a realsense, organic teas are a concentrated liquidfertilizer and inoculum of beneficialmicrobes.

It is worth noting that between 50 and 80percent of a plant’s photosynthates (sugars,complex carbohydrates, amino acids andproteins) are translocated below ground intothe root system of most plants (ElaineIngham, pers. comm.). Of this amount,40 to 60 percent are released by roots as exu-dates that supply food and create the condi-tions for colonization of soil microorganismsliving in the rhizosphere (the microscopichabitat surrounding roots). These organ-isms, in turn, excrete, die, decay and areconsumed by other organisms in the soil’sfood chain. Through this process of growth,death and decay, the waste and by-productsof soil microbes become macro and micro-nutrients for plants. From these facts, onemight hypothesize a profound reciprocal(symbiotic) relationship between plants andmicrobes as yet unexplained.

Teas Help Build Soil StructureThe microorganisms found in organic teasexcrete organic gums and resins that, togeth-er with fungal hyphae, bind soil particlesinto structural aggregates, improving bothsoil structure and water-holding capacity.Thus, when organic teas are applied as a soildrench, they can promote good soil struc-ture.—RM & JM

Continued from previous page

15

W I N T E R 2 0 0 1 N U M B E R 9

7 Andrews, JH, Harris RF. Compost extracts and thebiological control of apple scab. Can. J. Plant Path.1992;14:240 (Abstr.).

8 Elad Y, Shtienberg D. Effects of compost waterextracts on grey mould, Botrytis cinerea. CropProtection 1994;13 (2):109-114.

9 Stindt A, Weltzien HC. Der Einfluss von wassrigen,mikrobiologisch aktiven Extrakten von kom-postiertem organischen Material auf Botrytis cinerea.Rijisuniversiteit Gent 1988;53: 379-388.Mededelingen Faculteit Landbouwwetenschappen.

10 Weltzien HC, Ketterer N. Control of DownyMildew, Plasmopara niticola (de Bary) Berlese et deToni, on grapevine leaves through water extractsfrom composted organic wastes. Phytopath.1986;76:1104.

11 Khalifa O. Biological control of Fusarium wilt ofpeas by organic soil amendments. Ann. Appl. Biol.1965;56:129-137.

12 Hoitink HA, van Doren DM, Schmitthenner AF.Suppression of Phytophthora cinnamomi in a com-posted hardwood bark potting medium. Phytopath.1977;67:561-565.

13 Ketterer N, Weltzien HC. Wirkung von Kompost-und Mikroorganismen Extraklenauf den Befall terKartoffeldurch Phytophthera infestans. Mitt. Biol.Bundesanst. 1988;245-346.

14 BioCycle Staff. Applying compost tea to preventpotato blight. BioCycle 1997 May; 53.

15 Budde K, Weltzien HC. Untersuchungen zurWirkung von Kompostextrakten undKompostsubstraten im Pathosystem Getreidt-EchterMehitau (Erysiphe graminis). Mitteilungen derBiologischer Bundesanst 1988;245:366.

16 Boehm MJ, Madden LV, Hoitink HA. Effect oforganic matter decomposition level on bacterialspecies diversity and composition in relationship toPythium damping-off severity. Appl. Environ.Microbiol. 1993;59:4171-4179.

17 ChenW, Hoitink HA, Madden LV. Microbial activi-ty and biomass in container media predicting sup-pressivness to damping-off caused by Pythium ulti-mum. Phytopath. 1988;78:1447-1450.

18 Hadar Y, Mandelbaum R. Suppression of Pythiumaphanidermatum damping-off in container mediacontaining composted liquorice roots. Crop Protect.1986;5:88-92.

19 Hoitink HA, Kuter GA. Effects of compost ingrowth media on soilborne plant pathogens. In: TheRole of Organic Matter in Modern Agriculture. Y.Chen & Y. Avnimelech (eds), Martinus NyhoffPubl., Dordrecht and The Netherlands. 1985. pgs.289-306.

20 Chung YR, Hoitink HA. Interactions between ther-mophilic fungi and Trichoderma hamatum in sup-pression of Rhizoctonia damping-off in a bark com-post-amended container medium. Phytopath.1990;80: 73-77.

21 Hadar Y, Mandelbaum R, Gorodecki B. Biologicalcontrol of soilborne plant pathogens by supressivecomposts. In: Biological Control of Plant Diseases:Progress and Challenges for the Future. E.C.Tjamos, G.C. Papavizas and R.J, Cook (ed.),NATO ASI Series No. 230. Plenum Press, NewYork, NY. 1992. pgs 79-83.

22 Hoitink HA, Fahy PC. Basis for the control of soil-borne plant pathogens with composts. Annual Rev.Phytopath. 1986;24:93-114.

23 Lopez-Real J, Foster M. Plant pathogen survivalduring the composting of agricultural organicwastes. In: Composting of Agricultural Wastes.J.K.R. Glasser (eds), Elsevier Applied SciencePublishers, New York, NY. 1985.

24 Lumsden RD, Lewis JA, Miller PD. Effect ofcomposted sewage sludge on several soilbornepathogens and diseases. Phytopath. 1983;73:1543-1548.

25 Van Assche C, Uytterbroeck P. The influence ofdomestic waste compost on plant diseases. ActaHorticultura 1981;126:169-178.

26 Weltzein HC, et al. Improved plant healththrough application of composted organic materialand compost extracts. pgs 377-379. In:Agricultural Alternatives and Nutritional Self-Sufficiency. A. Djigma et al. (eds), Proceedings ofthe IFOAM Seventh International ScientificConference, Ouagadougou, Burkina Faso. 1989.

27 Weltzein HC. Some effects of composted organicmaterials on plant health. Agriculture, Ecosystemsand Environment 1989;27:439-446.

28 Tranker A. Use of agricultural and municipalorganic wastes to develop suppressiveness to plantpathogens. Pgs 35-42. In: Biological Control ofPlant Diseases. E.C. Tjamos, G.C. Papavizas andR. J. Cook (eds). NATO ASI Series No. 230.Plenum Press, New York, N.Y. 1992.

29 BioCycle Staff. Tree bark compost for plant pro-tection. Pgs. 158-160. In: The Biocycle Guide toThe Art & Science of Composting. BioCycle:Journal of Waste Recycling. JG Press, Inc.,Emmaus, PA. 1991.

30 Hoitink HA, Composted bark: a lightweightgrowth medium with fungicidal properties. PlantDisease 1980;64: 142-147.

31 Hoitink HA, Fungicidal properties of compostedbark. Compost Science/Land Utilization 1980Nov-Dec.;24-27.

32 Hoitink HA, Inbar Y, Boehm MJ. Status of com-post-amended potting mixes naturally suppressiveto soilborne diseases of floricultural crops. PlantDisease 1991 Sept; 869-873.

33 Kai H, Ueda T, Sakaguchi M. AntimicrobialActivity of Bark-Compost Extracts. Soil Biol.Biochem. 1990;22 (7): 983-986.

34 Kuter GA, (et al). Fungal populations in containermedia amended with composted hardwood barksuppressive and conducive to Rhizoctonia dampingoff. Phytopath., 1983;73:1450-1456.

35 Nelson E B, Hoitink HA. The role of microor-ganisms in the suppression of Rhizoctonia solani incontainer media amended with composted hard-wood bark. Phytopath. 1983; 73:274-278.

36 Nelson EB, Kuter GA, Hoitink HA. Effects offungal antagonists and compost age on suppres-sion of Rhizoctonia damping-off in containermedia amended with composted hardwood bark.Phytopath. 1983;73:1457-1462.

37 Papavizas GC, Davey CB. Rhizoctonia disease ofbean as affected by decomposing green plantmaterials and associated microfloras. Phytopath.1960;50:516-521.

38 Tahvonen R. The suppressiveness of Finnish lightcoloured sphagnum peat. J. Sci. Agric. Soc. Finl.1982;54: 345-356.

39 Brinton WF. The Control of Plant PathogenicFungi by Use of Compost Teas. Biodynamics,

January/February 1995: 12-15.

40 Kloepper J, et al. Pseudomonas siderophores: Amechanism explaining Disease-Supressive soils.Current Microbiology 1980;4:317-320.

41 Wittig H. Final report: Fruit and ornamental dis-ease management testing program related to theuse of organic foliar amendments. OrganicFarming Research Foundation, Santa Cruz, CA.1996.

42 Boehm M J, Hoitink HA. Sustenance of microbialactivity and severity of Pythium root rot ofPoinsettia. Phytopath. 1992;82: 259-264.

43 Chao WI (et al). Colonization of the rhizosphereby biological control agents applied to seeds.Phytopath. 1986;76:60-65.

44 Hijwegen T, Buchenauer H. Isolation and identifi-cation of hyperparasitic fungi associated withErysiphaceae. Netherlands Jour. Plant Path.1984;90:79-83.

45 Scher F M, Baker R. Effect of Pseudomonas putidand a synthetic iron chelator on induction of soilsuppressiveness to Fusarium wilt pathogens.Phytopath. 1982;72:1567-I573.

46 Schonbeck F. Dehne HW. Use of microbialmetabolites inducing resistance against plantpathogens. Pgs 361-375. In: Microbiology of thePhyllosphere. N.J. Fokkema and J. van denHeuvel (eds), Cambridge Univ. Press, Cambridge,MA. 1986.

47 Redmond RD, Marois JJ, MacDonald JD.Biological control of Botrytis cinerea on roses withepiphytic microorganisms. Plant Disease 1987;71:799-802.

48 Wood R. The control of diseases on lettuce by theuse of antagonistic organisms. 1. The control ofBotrytis cinerea Pers. Ann. Appl. Biol. 1951;38:203-216.

49 Jager G, Velvis H. Biological control ofRhizoctonia solani on potatoes by antagonists. 4.Inoculation of seed tubers with Verticillium bigut-tatum and other antagonists in field experiments.Neth. J. Plant Pathol. 1985;91:49-63.

50 Meshram SW. Suppressive effect of Azobacterchroaccum on Rhizoctonia solani infestation ofpotatoes. Neth. J. Plant Pathol. 1984;90:127- 132.

51Hubbard JP, Hannan GE, Hadar Y. Effect of soil-borne Pseudomonas spp. on the biological controlagent, Trichoderma hamatum, on pea seeds.Phytopath. 1983;73:655-659.

52Papavizas GC. Trichoderma and Gliocladium:Biology, ecology and potential for biocontrol. Ann.Rev. Phytopath. 1985;23:23-54.

53Cantisano AB. Compost Teas—How to Make andUse. P.O. Box 1622, Colfax, CA 95713. 1994.

This complete project report (Project #97-40) is 47 pages, plus eight appendices. Themain report and bibliography are availablefrom OFRF by mail or by visiting our web-site (www.ofrf.org); project appendices maybe obtained by mail only and will be sentupon request.

16

I N F O R M A T I O N B U L L E T I N

Therefore, a study was undertaken to lookat the effectiveness of disease control withcompost extracts on some cash crops inthe Southern Interior of British Columbia.

Project Objectives■ To determine which compost extract is

more effective in reducing disease instrawberries, lettuce, broccoli and leeks;

■ To identify the point at which applica-tion of the compost extracts are moreeffective.

Experimental MethodsGeneral description of study siteThe trials took place at Wildflight Farmlocated in the floodplain of the ShuswapRiver near Mara in the North Okanaganregion of British Columbia. The annualrainfall of the area is approximately 1,300mm [51 in] with warm, humid summers.The plots were established on level orslightly undulating land with a soil of aclay loam texture. This particular farmprovides produce for the fresh market anda CSA, and thus grows a wide variety ofvegetables including brassicas, tomatoes,potatoes, salad greens, onions, garlic, leeks,strawberries, cucurbits, carrots and beets.

Crop planting and other detailsStrawberries were established three yearsprior at recommended densities. Plots weresuperimposed onto the existing strawberryfields and were ribboned off. Regular culti-vations were done to control weeds. Nofertilizer or sprays were applied throughoutthe strawberry season. Similarly, compostextract treatments were superimposed ontoexisting leek fields. Here the spacing wassix inches between plants and about threefeet between rows. Leeks were cultivatedfor weeds several times prior to harvest.Lettuce (“Paris cos” variety) and broccoli(“Pakman” variety) were seeded into trayswith the following soilless mix: 4:4:1 ofchicken manure compost, peat and ver-miculite, respectively. Some dolomitic limewas also added to adjust the pH to 7.Lettuce and broccoli seedlings were raisedin the greenhouse until ready for trans-

planting. During this time, overheadwatering was used and no extra fertilizerwas added. Lettuce was planted out at 1 ftx 1 ft spacing while broccoli was plantedat 1.5 ft x 3 ft spacing.

Compost extract preparationCattle compost from Greenleaf (Olds,Alberta) and chicken manure compostfrom a poultry farm in Armstrong, BritishColumbia, were used for the extractions.Both composts were actively turned forthe first month and then only once amonth for the next three months, thencured for another six months. A methodof compost tea extraction proposed byresearchers at the Wood’s Hole Laboratorywas used8. This resulted in an 8:1 water-to-compost dilution. Water was added tothe respective composts (cattle and chick-en) and the mixture was stirred for aboutten minutes every day of the week-longextraction period. The extract was filteredthrough several cheesecloths, stored out-side away from sunlight until used oncrops.

Application detailsThe compost extract was applied with abackpack sprayer that was rinsed thor-oughly with water before and after eachtype of extract. Strawberries and leeks werealready in the field, while lettuce and broc-coli were raised from seed and so weresprayed in the greenhouse, and dependingon the treatment, in the field as well.Crops were sprayed as long as weatherallowed (i.e. extended wet periods). Sprayswere applied at a rate that ensured cover-age of all foliage. Approximate applicationrates are listed below:

❖ Strawberries• Sprayed twice a week at 1.3 litres/m2

(0.03 gallons/ft2)

❖ Lettuce• In the greenhouse, about 50 ml (2 oz)

was applied to one seedling tray (200plants) prior to setting the lettuce out.

• Initially in the field the same sprayingregime as in the greenhouse was continueduntil the plants were larger.

• Sprayed twice a week at approximately1 litre/m2 (0.02 gallons/ ft2).

One of the major challenges facingorganic producers is disease man-agement. Losses in vegetable pro-

duction due to disease can be significantand in some cases, can devastate entirecrops. Cultural methods of disease controlare commonly used on organic farms. Theapplication of organic chemicals for diseasecontrol is often a last resort and regulatedwhile biological control is still not readilyavailable. The use of compost extracts pres-ents a simple, inexpensive and potentiallyeffective method to supplement on-farmdisease management.

The effectiveness of using composts fordisease control, particularly against fungalpathogens, has been studied extensively1,2.Composts of various kinds have been usedto reduce the incidence of Pythium andRhizoctonia in a variety of vegetables andfruits3,4. These results have led to furtherwork using filtered extracts of composts. Insome cases, the compost extracts were evenmore effective at controlling disease thanconventional pesticides5. Stindt andWeltzien6 at the University of Bonnachieved effective control of Botrytis cinereain strawberries as well as blight in potatoes.Similarly, powdery mildew and root rotwere significantly reduced in peas andbeets in other trials in Germany7. Theresults of studies on compost extracts havebeen variable and seem to be crop andregion specific, amongst other factors.

Project leader:Sylvia Welke,North Okanagan Organic Association

Co-investigator:Lena Armstrong, field assistant.

Cooperating growers:Hermann and Louise BrunsWildflight Farm, Mara, BC

Additional support:North Okanagan Organic Association

OFRF support: $3,945

Project period: 1999

RESEARCH REVIEW

Effectiveness of Compost Tea Extracts asDisease Suppressants in Fresh Market CropsSylvia Welke

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W I N T E R 2 0 0 1 N U M B E R 9

❖ Broccoli• In the greenhouse, about 50 ml (2 oz)

was applied to one seedling tray (90plants) prior to setting the broccoli out.

• Sprayed twice a week at approximately0.9 litres/m2 (0.02 gallons/ft2).

❖ Leeks• Sprayed twice a week at about 0.90

litres/m2 (0.02 gallons/ft2)

Plot layout and treatmentsStrawberries, lettuce and broccoli trialswere all laid out in a completely random-ized design while the leek trial was a ran-domized complete block design. Eachtreatment was repeated four times withinthe experimental plot. The following treat-ments were either imposed on existingplants in the field (strawberries and leeks)or applied in the greenhouse:

Strawberries and leeksa. cattle manure compost extractb. chicken manure compost extractc. waterd. control (no extract or water)

Lettuce and broccolia. cattle manure compost extract (applied

in the greenhouse only)b. cattle manure compost extract (applied

in the greenhouse and in the field)c. cattle manure compost extract (applied

only in the field)d. chicken manure compost extract

(applied in the greenhouse only)e. chicken manure compost extract

(applied in the greenhouse and in thefield)

f. chicken manurecompost extract(applied only in thefield)

g. water only (appliedin the greenhouseand in the field)

h. control (nothingapplied)

MeasurementsStrawberriesThe number andweight of ripe anduninfected, marketablestrawberries were takenevery two to three daysfor the length of the

harvest (approximately one month, fromJune 18, 1999 to July 16, 1999). A scale ofthe incidence of Botrytis cinerea on the sur-face of the berries was used. This scale issimilar to those used by other researchersinvestigating B. cinerea on strawberries9,10:

0 = no infection,1 = 1-5% berry surface affected2 = 6-15% berry surface affected3 = 16-50% berry surface affected4 = 51-95% berry surface affected

LettuceLettuce was harvested when heads were ofmarketable size during the August 20 toSeptember 3, 1999 period, generally twicea week. The weight before and after trim-ming infected leaves off the head wasrecorded. Both lettuce bottom rot(Rhizoctonia solani) and downy mildew(Bremia lactucae) were assessed together astotal disease affecting the lettuce head. Thefollowing disease rating scale was used:

1 = plant infected, but affected leaveswere removed with minimal trimming.2 = moderate infection of wrapperleaves, but infection did not extend intothe head (still marketable heads).3 = extensive infection (little or no mar-ketable head left after infected leaves areremoved)11.

BroccoliBroccoli was harvested when heads were ofmarketable size between September 22,1999 to October 15, 1999. Heads wereweighed and the head diameter was meas-

ured. The incidence of head rot(Rhizoctonia solani) was measured usingthe following scale12:

0 = no disease1 = 1% surface area affected,2 = 10% of surface area affected,3 = 30% of surface area affected4 = 60% of surface area affected5 = 100% of surface area affected

LeeksLeeks were harvested from November 3-9,1999. Weight after trimming diseasedleaves was taken and disease (Peronosporadestructor) incidence was assessed as pres-ent or not present.

Lab analysesSamples of compost and compost extractswere sent to NorWest Labs in Edmontonand Lethbridge, Alberta, for nutrient andmicrobiological analyses. At harvest, sam-ples of sprayed foliage from broccoli andleeks were sent to the lab as well.

Results are shown in Tables 1 and 2.

Data analysesAll data were analyzed for normality andheterogeneity of variance prior to anANOVA. Strawberry and leek data wereanalyzed as a one-way ANOVA (type ofcompost) while lettuce and broccoli datawas analyzed as a 2-way ANOVA (type ofcompost and time of application).Significantly different means were separat-ed using Tukey’s test. All statistical analyseswere done using SAS.

Compost

Table 1. Chemical and biological characteristics of compost feedstock used for tea extracts.

Chicken manurecompost

pHEC

(mS/cm)NH4+/ NO3-

(%)Total K

(%)

0.33

0.18

Ca(%)

Na(%)

Fecalcoliforms(MPN/g)

Total P(%)

Mg(%)

Total S(%)

Salmonella

6.6 41.43 0.43 1.46 12.5 0.23 0.85 0.54 < 3 none

Cattle manurecompost

7.0 14.15 < 0.02 0.88 0.82 0.12 0.53 0.31 930 none

Compost tea extract

Chicken manure teaextract

Cattle manure teaextract

pH KCa

(ppm)Na

Mg(ppm)

SO4Fecal

coliforms(CFU/100ml)

Salmonella

7.33 61.3409 83.2 117 72.6 80 none

7.57 0.51 130 9.13 17.7 7.86 1.17 3500 none

2.47

Table 2. Chemical and biological characteristics of compost tea extracts.

E.C.(dS/cm)

Nitrate(mg/L)

154

3.01

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I N F O R M A T I O N B U L L E T I N

ResultsCompost and compost tea analysisThe analyses yielded few surprising results.Both cattle manure compost and itsextract had higher fecal coliforn counts,yet these were still low enough to fallwithin acceptable limits and were notdetected in the crops tested.

StrawberriesThe number of berries harvested per har-vest period varied between a low of 17early in the season to 186 at peak harvest.There was a trend of greater berry yieldswith the application of cattle compostextract compared to the control and chick-en compost extracts, although this differ-ence was only significant at the 0.10 alphalevel and only at certain harvest dates (Fig.1). Applications of cattle compost extractand water yielded similar berry weightsbut were often higher than the control.Berries treated with extracts from chickenmanure compost generally yielded lessthan all other treatments. The percentageof berries with no surface rot was not sig-nificantly different among treatments,although in the first half of the harvest,the control plots generally had fewerhealthy berries (class=0) compared tosprayed plots. Berries infected withBotrytis in any of the other disease classeswere similar with application of compostextracts, water or no application at all.

LettuceAt every harvest, two to three lettuceheads were sampled. There was no consis-tent trend in either lettuce weight harvest-ed (after trimming off diseased leaves) orin disease incidence with compost extractapplication. In fact, the control had higheraverage lettuce harvest weights comparedto other treatments while plots sprayedwith cattle compost extract had the lowest.(F=2.66, P=0.05) (Fig. 2). Greenhouse-only application of extracts producedheavier lettuce heads with lower diseaseincidence compared to application only inthe field or both in the field and in thegreenhouse (Fig. 3.). The type of compostextract and the time of application did nothave an effect on any other variables meas-ured for lettuce.

BroccoliBroccoli heads were harvested when theywere of marketable size; two to three heads

early in the season and four tosix heads during peak harvesttime. The effect of compostextract type and applicationtime was analyzed over theentire broccoli harvest periodand was also separated into andanalyzed by two harvest dates,early and late. No significantdifferences were found withrespect to compost extract typeat any time yet there wereinteractions between composttype and application time. Theapplication of cattle compostextract generally increased theweight of marketable headscompared to other treatmentsand the control (Fig. 4). Thiswas particularly true when cat-tle compost extract was appliedin the field only (F=4.53,P=0.024).

Both the control and theapplication of water resulted inlower average broccoli headweights. Similar effects of thecattle compost was observed forbroccoli head diameter(F=3.05, P=0.07). The percent-age of head rot was not signifi-cantly different among treat-ments, however, broccoli incontrol plots had a lower aver-age percentage of rot (Table 3).

There was no clear effect oftime of compost extract appli-cation, yet applying theextracts only in the field oronly in the greenhouse resultedin higher average head weightcompared to application atboth times (Table 3). In con-trast, head diameter was gener-ally higher with application atboth times. A significantlylower percentage of head rotwas observed when extracts andwater were only applied in thegreenhouse (F=3.76, P=0.05).

LeeksThe month before harvest andthe harvest period of leek wasdistinctly wet. The extendedperiods of rain made extractapplication difficult and the

0

500

1000

1500

2000

2500

3000

Early season Mid-season Late season

Ber

ryw

eigh

t(g

)

Cattle Water

Control Chicken

Fig. 1. Strawberry weight from plots sprayed with cattleand chicken compost extracts, water and no applicationof sprays over a 1 month harvest period. Mara, BritishColumbia. 1999.

400

450

500

550

600

Control Chicken Water Cattle

Lett

uce

wt.

afte

rtr

imm

ing

(g)

0

100

200

300

400

500

600

Greenhouse Field andGreenhouse

Field

Lett

uce

wt.

afte

rtr

imm

ing

(g)

Fig. 2. Lettuce head weights with compost extract andwater application compared to control plots. Mara,British Columbia. 1999.

Fig. 3. Lettuce head weights at different times ofcompost extract application. Mara, British Columbia.1999.

19

W I N T E R 2 0 0 1 N U M B E R 9

crop was only sprayed when weather con-ditions allowed (8 times in October),rather than twice a week. Leeks were har-vested over a period of a week (wheneverthere was a break in the rain).Approximately 30 leeks were harvested perplot. There were no significant differencesin the various treatments in terms of leekweight after trimming diseased leaves. Asseen with the other crops, the applicationof chicken compost extract generallyresulted in lower leek weights (Fig. 5). Noother trends were observed in the inci-dence of disease with the different treat-ments.

Microbiological analyses of plant leavesafter compost extract applicationSamples of broccoli and leek were sentaway for microbiological analysis. NoSalmonella was detected on any of thesesamples. Total and fecal coliforms were lessthan 3 MPN/g of broccoli and leek thatreceived cattle compost extract while totaland fecal coliforms were 3 and 43 MPN/g(Most Probable Number/gram) for broc-coli and leek tissue sprayed with chickencompost extract, respectively.

DiscussionThe effects of compost extract applicationwere not consistent across all crops. Yet,some trends did emerge. Extracts from cat-tle manure compost were effective inincreasing marketable number and weightsof strawberries. The same extract alsoincreased the weight of broccoli heads.Lettuce and leeks did not show anyincreased harvest weights or reduced dis-ease incidence as a result of cattle compostextract application. Crops that receivedapplications of chicken compost extractshad lower average harvest weights after dis-

eased parts were removed,except for lettuce. It is pos-sible that the chicken com-post extract had somemicroorganisms associatedwith it or metabolitesthereof that may have fur-ther contributed to diseaseprogression or had someother negative effect on

plant growth. It is also not clear why thecattle compost extract would have had asimilar effect to water spray, unless aftersome storage time, the extract lost its‘potency’ and had attributes more similarto the water treatment.

Disease incidence in strawberries andbroccoli did not vary significantly amongplots, yet compost applications oftenresulted in a greater average percentage ofhealthy crops compared to the control.This seems to indicate that there was someeffect either related simply to the sprayingof something liquid or to something asso-ciated with the extracts. Lettuce and leeks,however, did not show any clear responseto compost extract application. Possibly, ifcompost extracts are effective as a result ofan induced defense reaction of the plant assuggested by Samerski and Weltzien13, let-tuce and leeks may be crops that are notreadily induced in this way. This studyalso lends support to the idea that differ-ent crops respond differently to extractsfrom a variety of sources (e.g. lettuce didnot react to cattle extract as did the othercrops).

The dilution of extracts in this studywas 1:8 from the original compost; arecipe based on various research litera-ture8,14. It is possible that this was toodilute for a consistent, significant effect.In fact, researchers have found that dilu-tions of extracts can reduce disease inhibi-tion dramatically9,14. Compost extractincubation time also appears to be a vari-able in their effectiveness against disease.Urban and Trankner15 found that 24 hourextracts from horse and cattle manurecomposts effectively controlled gray moldin beans. Others have only found diseasesuppression after an extraction periodranging from 7 to 14 days9,16. Someresearchers suggest that compost extractslose their efficacy if they are not usedwithin about one week of preparation17.In this study, extracts were prepared inlarger batches, extracted over a one weekperiod and were used up to three weeksafter preparation. It is possible that themechanism responsible for inhibiting dis-ease was much reduced as the compostextract ‘aged’. This phenomenon seems tocoincide with increased berry weights earlyon (when the extracts were freshly pre-pared) with cattle compost extract applica-

0

100

200

300

400

500Ca

ttle

field

only

Cattl

efie

ld+g

reen

Cattl

egr

eenh

ouse

Chick

enfie

ldon

ly

Chick

enfie

ld+g

reen

Chick

engr

eenh

ouse

Cont

rol

Wat

er

Bro

ccol

ihea

dw

gt.(

g)

Fig. 4. Effect of compost tea extract application and application time on broccoliweight. Mara, BC. 1999.

Compost type Head rot (%)

Control

Cattle

Chicken

Water

1.1 (0.6)

2.0 (0.8)

2.6 (0.8)

5.5 (3.7)

Application timeBroccoli head wt.

(g)Diameter

(cm)Percentage rot

Field only 390 (14) 15.7 (0.4) 3.6 (1)

Greenhouse only 383 (18) 15.7 (0.3) 0.6 (1)

Greenhouse and field 343 (14) 18.2 (2.8) 2.9 (1)

Table 3. Effect of compost teaapplications on broccoli head rot.

Table 4. Effect of application time on broccoli headweight, diameter and percentage of head rot.(Standard error shown in parentheses.)

20

I N F O R M A T I O N B U L L E T I N

time, compost usedand crop to whichthey are applied.Consistency andmaturity of the com-post to be extractedare yet more variables.Evaluation is necessaryon specific crops andspecific disease organ-isms over a period ofseveral years toaccount for year toyear variations inweather which can sig-nificantly influence

disease dynamics. Werecommend that at leastanother season is

required to follow up on these initialresults and to focus on strawberries andbroccoli. A repeat of the initial experimentis necessary but we also suggest incorporat-ing another extract dilution, an aerobicallyprepared extract and the use of only “fresh”compost extracts.

❁Sylvia Welke’s complete project report (Project#99-31) is 10 pages, including 8 figures.Copies may be obtained from OFRF or byvisiting our website at www.ofrf.org.

References1 Weltzien H. Biocontrol of foliar fungal diseases

with compost extracts. In: J.H. Andrews and S.Hirano (eds.) Microbial ecology of leaves. NewYork, NY: 1991. pp. 430-450.

2 Hoitink HA, Stone AG, Han DY. Suppression ofplant diseases by composts. HortScience1997;32(2):184-187.

3 Gottschall RC. et al. Verwertung von Kompost ausBioabfall: Aufbereitung von Frisch undFertigkomposten. In: Fricke K et al (eds.),Zwischenbericht Forschungsprojeckt: Grunebiotonne Witzenhausen. 1987.

4 Weltzien H, Ketterer N. Control of downy mildew,Plasmopara viticola (de Bary) Berlese et de Toni,on grapevine leaves through water extracts fromcomposted organic wastes. Journal ofPhytopathology 1986;116: 186-188.

5 Weltzien H et al. Improved plant health throughapplication of composted organic materials andcompost extracts. 7th IFOAM InternationalScientific Conference, Burkina Faso, January1989.

6 Stindt A, Weltzien HC. Der Einsatz von kompos-textrakten zur bekampfun von Botrytis cinerea anerdbeeren ergebnisse des versuchsjahres 1987.Gesunde Pflanzen 1988;40:451-454.

tion; this was not evident later on.There appears to be some controversy

about how extracts are prepared, anaerobi-cally or aerobically. Cronin14 and cowork-ers, for instance, found that anaerobicallyprepared extracts from spent mushroomsubstrate were much more effective atinhibiting apple scab than aerobicallytreated extracts. Weltzien1 and Brinton8

also promote the anaerobic method ofcompost extract preparation. Theseresearchers suggest that the likely disease-suppressive effect is a result of a metaboliteproduced by anaerobic microorganisms inthe extract14. In contrast, there is also evi-dence that indicates that aerobically pro-duced compost extracts are much moreeffective18. Microbiological studies havealso shown that aerobic microbes dominatecompost2. The method used in this experi-ment was largely anaerobic with only occa-sional stirring during the extraction period.If, indeed, it is an aerobic microbial popu-lation that is responsible for disease sup-pression, then the extracts in this studywould have been relatively ineffective.

Given that this growing season wasunusually cool and wet, it is possible thatpopulations of pathogens were favored andcould easily out compete any beneficialorganisms associated with the extracts.High pathogen populations could also beless impacted by inhibitory substances pro-duced by organisms in the extracts.

The effectiveness of compost extractsappears to depend on many factors includ-ing method of preparation, extraction

7 Thom M, Moller S. Untersuchungen zur wirk-samkeit wasseriger kompostextrakte gegnuberedem erreger des echten mehltaus an gurken.Thesis. Gesamthochschule Kassel 1988.

8 Brinton WF. The control of plant pathogenic fungiby use of compost teas. Biodynamics 1995Jan./Feb.

9 Elad Y, Shtienberg D. Effect of compost waterextracts on grey mould (Botrytis cinerea). CropProtection 1994;13(2):109-114.

10 Archbold DD, Hamilton-Kemp TR, Barth MM,Langlois BE. Identifying natural volatile com-pounds that control gray mold (Botrytis cinerea)during postharvest storage of strawberry, blackber-ry and grape. Journal of Agricultural Food andChemistry 1997;45:4032-4037.

11 Mahr SE, Stevenson WR, Sequeira L. Control ofbottom rot of head lettuce with iprodione. PlantDisease 1986; 70(6):506-509.

12 Canaday CH. Effects of nitrogen fertilization onbacterial soft rot in two broccoli cultivars, oneresistant and one susceptible to the disease. PlantDisease 1992;76(10):989-99 1.

13 Samerski C, Weltzien HC. Untersuchungen zumwirkundsmechanismus von kompostextrakten impathosystem zuckerrube - echter mehltau.Zeitschrift fur Pflanzenkrankheiten undPflanzenschutz 1988;95(2):176-181.

14 Cronin MJ, Yohalem DS, Harris RF, Andrews JH.Putative mechanism and dynamics of inhibitionof the apple scab pathogen Venturia inaequalis bycompost extracts. Soil Biology and Biochemistry1996;28(9):1241-1249.

15 Urban J, Trankner A. Control of grey mould(Botrytis cinerea) with fermented compost/waterextracts. In: Fokkema NJ, Kohl J, Elad Y (eds.).Biological control of foliar and post-harvest dis-eases. Proceedings of a Workshop. West PalearcticRegional Section 1993;16: 8-11.

16 Ketterer N, Fisher B, Weltzien H. Biological con-trol of Botrytis cinerea on grapevine by compostextracts and their microorganisms in pure culture.In: K. Verhoeff, N. Malathrakis and B.Williamson (eds.), Recent Advances in BotrytisResearch. Proceedings IO’ International BotrytisSymposium, Heraklion, Crete, Greece, April 5-10,1992, pp. 179-186.

17 Brinton WF, Trankner A, Droffner M.Investigations into liquid compost extracts.Biocycle 1996 Nov.

18 Anonymous. Compost teas in agriculture.BioCycle 1996 Dec.

200

250

300

Control Cattlecompostextract

Water Chickencompostextract

Leek

wei

ght

(g)

Fig. 5. Effect of applied compost tea extracts and water onleek weights compared to control plots. Mara, BC. 1999.

over time 2,3,4. The degree of curing orcompost maturity has been shown to beimportant to maximize suppressive benefitsin other systems2,4,5. Improperly or inade-quately cured compost materials may lackdisease suppressive qualities. Prior to pro-moting the use of any compost materialbased upon disease suppressive quality,more baseline information on the durationand nature of the suppressiveness isrequired for growers to make sound man-agement decisions.

There are several biological and chemicalindicators of compost maturity andsuppressiveness5,6,7, but these measure-ments require time and special equipment.A test has been developed to measure com-post maturity within a short time frame

(Woods End Research Laboratory,Maine)8. This test may also have some pre-dictive value for ranking or comparingcomposts for disease suppressiveness, butthis has not been evaluated. Such a toolmay be very useful to growers for monitor-ing composts for optimal maturity to max-imize most suppressiveness. Compost ageand suppressiveness could be optimized toprevent N immobilization and to enhancelikelihood of healthy, vigorous seedlingproduction.

Organic systems, which already use reg-ular inputs of green plant and animalmanures, have been shown to have diseasesuppressive soils5,11. Adding highly sup-pressive compost may not further reducedisease incidence in these systems. Little

21

W I N T E R 2 0 0 1 N U M B E R 9

information is available on the degree ofsuppressiveness of organically managedsoils and there are no reports of changes insuppressiveness of these soils with additionof highly suppressive composts.

Project Objectives■ Analyze several animal manure-based,

organic-approved compost products forsuppression of important soil-bornepathogens of vegetable crops in theNortheast.

■ Determine applicability of a farmer-based test kit for assessment of com-post maturity to predict suppressive-ness.

■ Evaluate compost effects on plant standand crop composition.

■ Determine changes in microbial activi-ty, disease suppressiveness and soilnitrate nitrogen of organically managedsoils after addition of a compost.

Materials and MethodsCompost materials and testing. Five com-post products were selected for field andgreenhouse experiments based on collabo-rating organic grower’ preferences. Onecompost was grower-made and the restwere certified and commercially available(Table 1). The grower compost was animalmanure and food-waste based. Compostswere analyzed for nutrient compositionthrough the Cornell Nutrient AnalysisLaboratories. Microbial activity was deter-mined by measuring the rate of hydrolysisof fluorescein diacetate (FDA)7, which hasbeen correlated with compost disease sup-pressiveness3,5. Compost maturity was esti-mated using Wood’s End Lab’s “Solvita”Compost Maturity Test Kit, which esti-

Numerous root rot diseases arewidely distributed and causesevere yield losses on many veg-

etable crops grown in New York State andthe northeast region of the US, includingbeans, table beets, cabbage, peas, sweetcorn, lettuce, carrots, onions, tomato,potato, several cucurbits and others1.Control of these diseases has traditionallydepended upon rotations and soil qualityimprovement strategies. One characteristicof compost which is receiving much atten-tion is the observed suppression of soil-borne diseases in crops grown on com-post-amended soils. Although organic sys-tems have been shown to have somedegree of suppressive soils, use of spring-applied highly suppressive compost maydecrease the severity of root rot diseases,particularly during cooler, wet weathercharacteristic of the Northeast.

The primary mode of action of compostin disease suppression has been shown tobe the enhanced microbial biomass andactivity, which contributes to increasedmicrobial antagonism to pathogensaround plant roots. Disease suppressive-ness of compost-amended soils may alsobe partially explained by enhanced nutri-ent supply and improved soil physicalproperties. Different compost types as wellas different batches of one compost mayvary in disease suppressiveness, and thesuppressiveness of a batch may change

Impact of Disease Suppressive Composts onOrganic Vegetable Quality, Composition and Yield

Anusuya Rangarajan

Principal investigator:Anusuya Rangarajan, Asst. Professor,Cornell University, Ithaca, NY

Collaborators:Will Brinton, PhD., Woods End ResearchLaboratory, Mt. Vernon, MEAaron Gabriel, Cornell Coop. Ext.-Washington Cty.; certified organic vegetablefarmerLee Stivers, Cornell Coop. Ext.-Monroe Cty.Brian Caldwell, Cornell Coop. Ext.-Tioga Cty.

OFRF support: $5,000

Project period: April-December 1997

11.8

Compost Description pHMoisture

(%)

OrganicMatter

(%)

Total N(%)

Total C(%)

C:N ratio

A

B

C

D

E

farm made, mixed

dairy manure, commercial

poultry, no added carbon

poultry, added sawdust

dairy manure, commercial

4.80

7.82

7.37

8.77

7.82

70

6

6

4

30 36

81

14 0.6

65

78

2.8

6.1

2.0

1.5

39.5

8.6

30.0

28.7

14

14

5

14

14

Table 1. Compost tested in greenhouse and field experiments, 1997.

RESEARCH REVIEW

22

I N F O R M A T I O N B U L L E T I N

mates maturity based on respiration rate.Maturity is ranked from 1 (immature) to 8(highly mature) (Table 2). Results from theFDA hydrolysis and the test kit were com-pared to determine whether the kit couldsuggest a suppressive compost.

Field experiments. Three organic farm,four conventional farm and two researchstation trials were conducted to explore theimpact of composts on soil microbial activ-ity and disease suppression.

Sites were selected based on historicproblems with soil borne diseases, to exam-

ine compost effects on cropstand, tissue analysis and yieldand soil nitrate levels.Compost application rateswere based on grower prac-tices. No attempt was madeto control for differences innitrogen contribution ofproducts, since the primaryinterest was on effect of com-post on soil microbial activity.However, soil nitrate nitrogenwas also determined to assesspotential differences betweencomposted and non-compost-ed treatments.

Two cooperating organicfarms were located in thesouthern New York (Tompkinsand Tioga Counties) for thefollowing trials:

• Farm A: Grower-made compost ‘A’,(Table 1) was applied to one-half of theplots at a rate of 15 T/A. Four rows ofspinach were seeded after one week, onJune 15.

• Farm B: A commercial dairy manurecompost ‘B’ (Table 1) was applied toone-half of the plots at a rate of 2.5 T/A.Four rows of beans were seeded five dayslater, on June 24.

Plots at each site measured 12’x 15’ andfour replicates of a composted and non-composted control were used. Stand

counts and leaf tissue samples were takenfrom eight feet of the middle two rows ineach plot of the bean trial on July 10 andfrom five feet of the middle two rows inthe spinach trial on July 3. Leaf sampleswere dried and analyzed for total nitrogenand mineral composition (Cornell ICPLaboratory). Soils were sampled from allplots on July 16 and analyzed for nitratelevels and microbial activity.

The third grower trial took place at anorganic farm in western New York:

• Farm C: Two commercial poultry com-post products ‘C’, ‘D’ (Table 1), wereapplied at a rate of 2 T/A, one weekbefore seeding. Beets were seeded oneweek later into these plots on June 2.

Stand counts and leaf tissue sampleswere taken July 8. Soils were sampled onthree dates- June 2, July 7, and July 23,and analyzed for nitrate nitrogen concen-trations. On June 2 and July 23, totalmicrobial activity in the top 2 inches ofsoil was evaluated, using the same enzy-matic assay applied to the composts.

A third poultry compost trial was estab-lished at the Cornell Vegetable ResearchFarm in Geneva, NY:

• Farm D: Poultry composts ‘C’ and ‘D’were applied at 4 T/A and compared toa no compost control. These were thesame composts used at the organic beettrial, but at twice the rate. Beets were

seeded on June 12.

Soil and tissue samples weretaken on July 23. At harvest(September 27), final plantstand, yield and incidence ofroot rot were recorded.

On two conventionallymanaged research farms, thepoultry compost ‘C’ (Table 1)was examined for effects onsoilborne disease and yield. Thisproduct had previously reducedlevels of Rhizoctonia root rot onbeets. To examine residual com-post effects from previous years,a research site was identifiedthat had received an applicationof this compost in 1996, at theCornell Vegetable Research

Solvita TestResult

1

2

3

4

5

6

7

8

Approximate Stage of Composting Process

Fresh, raw compost; new mix; extremely high rate ofdecomposition; very odorous; high in volatile organicacids.

Very active decomposition, moderately fresh compost;very high respiration rate; needs intense aeration.

Compost is moving past the active phase of decomposi-tion; ready for curing, reduced need for intensive mgmt.

Compost in medium active stage of decomposition; maybe ready for curing.

Aeration needs reduced; curing; significantly reducedmanagement needed.

Well-matured, aged compost; cured; ready for mostuses.

Highly matured compost; well aged; like soil; ready formost uses.

Table 2. Interpretation guide provided with SolvitaCompost Maturity Test Kit. (Information summarizedfrom materials supplied by Wood’s End Laboratory.)

Farm Crop Treatment1Plant

stand2

(num/ft)

Tissue analysis (%)3

A

B

C

D

spinach

beans

beets

beets

Compost A

No compost

Compost B

Compost C

No compost

Compost D

No compost

Compost C

Compost D

No Compost

2.9 a

1.9 b

5.3 a

3.9 b

9.25 a

8.5 a

10.5 a

13.1 b

17.1 a

16.1 ab

3.31 a

3.36 b

3.88 a

3.74 a

3.46 a

2.84 a

3.01 a

4.32 a

3.72 b

3.85 b

0.54 a

0.50 b

0.34 a

0.33 a

0.53 a

0.55 a

0.65 a

0.43 a

0.41 a

0.38 a

7.33 a

7.84 a

4.55 a

4.22 a

8.93 a

8.48 a

8.99 a

5.05 b

6.05 a

5.20 b

1.25 a

1.36 a

2.55 a

2.62 a

1.27 a

1.28 a

1.33 a

1.79 a

1.81 a

1.99 a

0.79 b

0.91 a

0.44 a

0.46 a

1.53 a

1.4 a

1.44 a

1.1 a

1.03 a

1.14 a

306 a

374 a

78 a

72 a

5862 a

6222 a

3724 b

9163 a

9094 a

5363 b

70 a

66 a

128 a

127 a

72 a

74 a

72 a

148 a

136 a

149 a

Na (ppm)N P K CA Mg MN (ppm)

Table 3. Plant stand and tissue analysis from plants grown on composted and non-compostedplots. Farms A, B and C were organically managed and Farm D was a Cornell Research Farm.

1 Spinach received 15 T/A compost and beans received 2.5 T/A. Beets on farm C received 2 T/A of each product and Farm D received 4 T/A of eachproducts. Control (no compost) treatments received no supplemental N on organic farms. On farm D, control treatments received 120 lb/A N asammonium nitrate.

2 Numbers from same farm and in same column followed by the sam letter are not significantly different at the 5% level.3 Data for macronutrients is based upon a percent of dry matter or part per million for micronutrients. Analysis of other micronutrients indicated no

significant differences among treatments.

Active compost; young materials; high respiration rate;still needs intensive management.

23

W I N T E R 2 0 0 1 N U M B E R 9

Farm in Freeville, NY. In 1996, poultrycompost ‘C’ had been applied to a 12-ftband (rate of 4 T/A) across the center ofeach plot, with control (non-composted)sections adjacent to either side of theband. This site was selected for the follow-ing trial:

• Compost ‘C’ was applied to one half ofthe original band, at a rate of 4 T/A andmixed into the top 2 inches of soil.

This design allowed replicated comparisonof three treatments: a no compost control,1996 compost application, and 1996+1997compost applications.

Snap beans were direct-seeded on June 10,across the entire experiment. Soils were sam-pled mid season (July) to determine micro-bial activity and soil nitrate concentrations.Snap beans were harvested August 11, andabove ground biomass and bean yield wererecorded. Roots were evaluated for diseaseseverity using a 1 to 9 (9=severe root rot)scale (Abawi, personal communication).Naturally occurring pathogen populationsprovided the disease pressure in this experi-ment, as in the on-farm trials.

Soil nitrate nitrogen and microbialactivity analysis. On a soil sampling date,ten soil cores (8 inches deep) from eachplot were taken. Additional cores of thetop 2 inches were taken for microbialactivity tests. Soil nitrate was extractedand analyzed using standard laboratoryprocedures and results were represented asconcentration of nitrate nitrogen in drysoil.

The microbial activity of soil and com-post was estimated by the rate of enzymat-ic hydrolysis of fluorescein diacetate(FDA) by soil microorganisms7. Soil orcompost (.7 g fresh weight) was incubatedin phosphate buffer for exactly 40 min-utes. Enzymes present in the soil or com-post cleave FDA to produce a yellow-green compound. The color intensity pro-duced over the incubation period wascompared to known concentrations ofcleaved FDA to provide an estimate of therate of microbial enzymatic activity.Results were presented as micrograms ofFDA hydrolyzed per minute per gram dryweight of soil or compost (ug-min-1-g-1).Higher rates of microbial activity resultedin higher FDA hydrolysis values.

Greenhouse Disease Evaluations. Threecommercially available compost products-two poultry manure based (C, D) and onedairy manure based (E) were screened forsuppressiveness to Pythium andRhizoctonia using a greenhouse diseasebioassay. A rate equivalent to that used infield trials (4 T/A) was calculated to be5% v/v compost:peat mix. Composts andthe peat-based media were mixed thor-oughly, and then subsamples were eitherautoclaved on three consecutive days (tokill media microorganisms) or held moistuntil beginning the bioassay. Sterilizedcomposts allow isolation of compost nutri-ent or physical effects on plant growth anddisease incidence. Both pathogens weregrown on sterilized wheat kernels for 6days, prior to commencing the trial. Justprior to seeding, the autoclaved and non-autoclaved soil media were inoculatedwith one of the pathogens, by grindingthe infected wheat kernels in a food milland dispersing evenly throughout thesoil/compost mixes. Seeds of both cucum-ber and beets were sown into these mixes.Plant emergence, appearance and diseasesymptoms were recorded once per week.

At the end of the 4-week experiment,plant fresh and dry weights (above groundportion only) were measured. Soil nitrate-N, microbial activity, soluble salts, and pHwere also recorded at the end of the trial.A second greenhouse experiment was con-ducted to evaluate the impact of two‘field-equivalent’ rates of compost on beetgermination and early growth. A soil mix(1:1 v/v peat:field soil) was amended withcompost at two rates, equivalent to 2 or 4T/A. No-compost mix was used for a con-trol. One half of the pots were inoculatedwith Rhizoctonia as described above. Tenbeet seeds were placed in each pot andplant stand was recorded every two tothree days for four weeks.

Results and DiscussionCompost analyses. Compost analysisshowed that the tested products varied inboth maturity and stability. In commercialcomposts ‘B’ through ‘E’, the compostingprocess was carefully monitored, and uni-formity of the products over several batch-es was high.

The poultry compost ‘C’ had no carbonadded during composting, as evidenced by

the low C:N ratio and a strong ammoniasmell to the product. However, the highernutrient density of this compost (equiva-lent to a 3-4-5 N-P-K fertilizer) andobserved disease suppression in the fieldmade this product appealing to bothorganic and conventional vegetable grow-ers and fostered support for this researcheffort.

Poultry compost ‘D’ did have addedsawdust during production, no odor, andhad been cured for 3 months.

Composts ‘B’ and ‘E’ were both dairy-manure based. Compost ‘B’ was purchasedbagged product with little known aboutthe production history or length of curing.

Compost ‘E’ was widely used by NYorganic growers. Results from testing thisproduct in greenhouse studies are present-ed.

Nitrogen contributions from compostswere not controlled in these studies. Whenadded to field trials, the total nitrogensupplied by the composts were as follows:

• Compost ‘A’ added at 15 T/A provided840 lb N;

• Compost ‘B’ supplied at 2 T/A provid-ed 24 lb N;

• Compost ‘C’ added at 2 or 4 T/A pro-vided 244 or 488 lb N;

• Compost ‘D’ provided 80 or 160 lb N.

Not all of this N was available to thecrop; estimates of N availability within thefirst year of compost application will varyby the compost feedstock and maturity,and range from 5 to 50%. At this highend, composts are still considered imma-ture or unstable, and may be betterdescribed as ‘partially stabilized manure.’

Seven compost products were analyzedfor microbial activity, using the FDAhydrolysis method, and results rangedfrom 2 to 18 ug-min-1g-1 dry wt activity.The rate of FDA hydrolysis from com-posts would generally be expected to behigher than those found in soils. Researchwith peat-based potting mixes suggested aminimum FDA rate 3.2 ug-min-1g-1 drywt for suppressiveness to Pythium spp.10.Based on this measure, all but three ofthese composts could be considered aspotentially disease suppressive, providedthis threshold would apply to straight

24

I N F O R M A T I O N B U L L E T I N

compost as well. In potting mixes, the per-centage of compost on a volume basis isgenerally less than 25%. Solvita test kitresults for these composts ranged from 1 to6. Based upon interpretation informationprovided with the kit (Table 2), none ofthe composts was considered ‘finished’.Several were still very active and otherswere in the curing phase. In our studies,composts were grouped as either highlyactive (Solvita scores from 1 to 3) orapproaching curing (score 5 to 6).

A comparison of results from microbialactivity (FDA) and the Solvita CompostMaturity Test suggested that there may bepotential to use the test kit to estimatesuppressiveness (data not shown).However, results from these studies wereclustered in two ranges of the Solvita test.Additional comparisons of composts of dif-ferent maturity levels are required. Theseresults were very preliminary and alsodependent on the good correlationbetween microbial activity as indicated byFDA and actual disease suppression inbioassays. Once a compost product is char-acterized for effects on various soil bornediseases, however, this kit may be useful totrack both maturity and potential diseasesuppressiveness.

Field Experiments.Plant stand, disease incidence and tissueanalysis. Late-season disease pressure wasvery low in the on-farm trials, despiteselection of fields with historical soil-bornedisease problems. Evaluating crop standsprovided a measure of early season diseasepressure as well as seed-bed soil quality forcrop emergence. Compost applications sig-nificantly increased plant stands in thespinach and bean. on-farm trials (Table 3).Although a low rate (2.5 T/A) of dairymanure compost ‘B’ was applied, stands ofbeans were improved by 25%. A low rateof poultry composts ‘C’ and ‘D’ did notimprove stands of organic beets. Whenpoultry compost ‘C’ was applied at a high-er rate (4 T/A) to conventionally grownbeets, stands were reduced compared toother treatments, suggesting potential saltdamage.

Only the conventional bean experimentsupported previous observations of reduceddisease pressure with compost applicationin the field. A high rate (4 T/A) of poultry

compost ‘C’ applied to conventionallymanaged beans did not affect plant standsignificantly. Previous applications of thesame product one year earlier also did notaffect stand. However, the incidence ofroot rot in this experiment was significant-ly reduced by 1997 spring compost appli-cations (data not shown).

Mid-season tissue analysis of spinachfrom the organic farm ‘A’ did indicatesome statistically significant differencesamong composted and non-compostedplots, however these differences wereminor (Table 3). There were no significantdifferences among treatments in the on-farm bean experiment. Beet tops were sig-nificantly higher in sodium in compostedplots in both the on-farm and research sta-tion experiments. Beets respond positivelyto sodium applications, and historicallysodium was applied to partially substitutefor potassium fertilizers. Poultry compostscontain higher sodium than other animalmanure composts. At both the low (2 T/A)and high (4 T/A) rates, sodium concentra-tion in beet leaves was increased.

Soil nitrate nitrogen and microbialactivity levels. Compost additions signifi-cantly increased midsea-son soil nitrate nitrogenmeasurements only atfarm C, in organicbeets. In this case,addition of the highN poultry compost‘C ‘contributed tohigher mid-seasonsoil nitrate N concen-trations, up to tentimes the levels ofother treatments.Differences in soilnitrate N among thetreatments on thisfarm continued tolater in the season(data not shown). Atthe first sample date,there was no signifi-cant difference in soilnitrate N under thethree treatments. Bymid-season, soil nitratelevels under the con-trol and compost ‘D’

treatments at this farm were low (3 to 5lb/A) and may have become growth limit-ing. However, by the end of the season(soil sampling day 3), high levels of nitrateN were still detected under compost ‘C’,and could contribute to leaching losses ofN from this treatment. The more stablepoultry compost ‘D’ did not contribute toexcess soil nitrate N.

Soil microbial activities at the midseasonsampling date also were not affected bycompost additions, except at farm A(Table 4). All composts had FDA valuesabove a threshold of 3.2 ug-min-l-g-1 sug-gested for suppressiveness10 and wereapplied and incorporated into the surface3 inches of soil. On organic farm C, soilsamples were also taken on June 2 andanalyzed for microbial activity. At this ear-lier planting date, differences were detect-ed in microbial activity among the threetreatments, but these were not statisticallysignificant at levels desirable for research.Plots with no compost averaged 1.47 ug-min-l-g-1, those with high N poultry com-post ‘C’ averaged 1.95 ug-min-l-g-1 andthose with poultry compost ‘D’ averaged1.54 ug-min-l-g-1. Microbial activity of

Farm Crop Treatment1Soil NO3-N2

(lb/a)FDA3

(ug/min/g)

A

B

C

D

Spinach

Beans

Beets

Beets

Compost a

No compost

Compost b

No compost

Compost c

Compost d

Compost d

No compost

Compost c

No compost

15 a4

15 a

42 a

32 a

31 a

3 b

5 b

42 a

28 a

52 a

1.05 a

0.73 b

1.12 a

0.99 a

0.84 a

0.88 a

0.89 a

0.54 a

0.57 a

0.57 a

1 Spinach received 15 T/A compost; beans received2.5 T/A; beets on farm Creceived 2 T/A; beets on farm D received 4 T/A compost.

2 Farm A/spinach soil sampled 7/16/97; Farm B/bean soil sampled 7/23/97;Farm C beet soil sampled 7/23/97; Farm D beet soil sampled 7/23/97. Valuesfor spinach and beans represent mean of four replicate samples, each com-prised of eight cores taken to an 8 in. depth. Beet soil nitrate values frommean of three replicates.

3 FDA values from surface 2 inches of soil. Values represent mean of three orfour replicates.

4 Numbers in same group and column followed by the same letter are not sig-nificantly different at the 5% level.

Table 4. Soil nitrate nitrogen and microbial activity levels atmidseason sampling of composted and non-compostedfields at four farms. New York. 1997.

25

W I N T E R 2 0 0 1 N U M B E R 9

soils were lower at mid season samplingdate (Table 4). The low rates of compostapplied may have been insufficient toresult in a measurable increase in microbialactivity at a midseason test of these soils.

Measurements of microbial activity werehigher at all organically managed on-farmtrials than at conventionally managedfarms. On conventionally managed beetfarms with the same soil type and withintwo miles of organic farm C, soil microbialactivities ranged from .43 to .45 ug-min-l-g-1as compared to .84 to .89 ug-min-l-g-1

on organic farm C, on the same samplingdate. This observation of higher soil micro-bial activity under organic managementsystems compared to conventional systemshas been previously reported11.

Crop yields. Crop yields were only record-ed for the two beet and the conventionalbean experiments.

Marketable yields of beets were signifi-cantly higher under the high N poultrycompost ‘C ‘on both farms. Above groundbiomass was also higher. Yields in the con-ventional trial were twice those on theorganic farm, however, twice the amountof compost was used at that site. Yieldresults correlated with the high soil nitrateN associated with this compost ‘C’. Thepoultry compost ‘D’ also enhanced yieldsover the control in the research stationtrial. In beans receiving compost ‘C’ in1997, plot yield and individual plant beanyield was significantly increased and totalplant weight increased over the control andplots which had received compost in 1996.Despite the potential nutrient carryoverfrom compost applied in 1996, there wasno observed yield effect.

Greenhouse Compost Trials. In the initialgreenhouse experiment, attempts to estab-lish a high population density of bothPythium and Rhizoctonia in the media test-ed in the greenhouse disease bioassay wereunsuccessful. While there was somedecreased growth of both beets and cucum-bers in pathogen-inoculated soils, there wasnot the expected 50% reduction in plantnumber due to these damp-off diseases (datanot shown). It is suspected that the wheat-cultured inoculum had too low a populationdensity to adequately colonize the mediawithin the short experimental duration.

However, the various compost treat-ments had significant effects on plantemergence rates and growth. Two of thetested composts, one poultry (‘D’) and theother dairy manure (‘E’) based, enhancedplant emergence rates and growth, particu-larly if microbial activity was intact (non-sterilized). Both beets and cucumbers hadsimilar final stand counts, but significantlyhigher fresh and dry weight in non-auto-claved ‘D’ or ‘E’ compost based mediacompared to autoclaved media and the no-compost control. The effect of these twocomposts was particularly pronounced forcucumbers. The similar plant stands andfresh/dry weights among the autoclavedmedias and the control indicated thatrelease of phytotoxic compounds as a resultof autoclaving was minimal. Soluble saltlevels and nitrate and ammonium-N con-centrations did not vary among autoclavedand non-autoclaved mixes of these twocomposts, and the no-compost control(data not shown).

Those treatments containing poultrycompost ‘C’ were phytotoxic to beet andcucumber growth, resulting in sloweremergence rates, and lower stand counts,plant fresh and dry weights than othertreatments. Sterilizing the media had noeffect on crop response, unlike thoseobserved for the other two composts. Thepoultry compost ‘C’ mixes had higher sol-uble salts and pH compared to other treat-ments, which contributed to poor plantgrowth in these treatments.

Because of the observed reductions inRhizoctonia root rot observed in the beanexperiment and previous beet research, anadditional greenhouse experiment was con-ducted to explored the effect of the high Npoultry compost ‘C’ on beet emergenceand disease resistance to Rhizoctonia. Thispoultry compost provided no reduction indisease incidence in these greenhouse stud-ies. Greater disease losses were observed incompost amended treatments than in non-compost amended treatments. Over the 4week study, total stand of beets wasreduced by 25% in the control, non-com-post treatments, as compared to 66% inthe treatments receiving the lowest rate ofcompost. The higher level of compost(equivalent to 4 T/A field rates) reducedgermination and plant stands over theexperiment. Thus, it appears that this

poultry compost product increased beetyield in field trials through a nutrient andnot a disease suppressive effect.

❁Anusuya Rangarajan’s complete project report(Project #97-09) is 29 pages, including 8tables and 3 figures. Copies may be obtainedfrom OFRF or by visiting our website atwww.ofrf.org.

References1 Sherf AF, MacNab AA. Vegetable diseases and

their control. Wiley& Sons, NY. 1986. 728pp.

2 Craft CM, Nelson EB. Microbial propertiesof composts that suppress damping-off androot rot of creeping bentgrass caused byPythium graminicola. Applied and Environ.Microbiol. 1996;62(5):1550-1557.

3 Hoitink H, Fahy AJ, Fahy PC. Basis for thecontrol of soilborne plant pathogens withcomposts. Ann. Rev. Phytopath.1986;24:93-114.

4 Kuter H, Hoitink HAJ, Chen W. Effects ofmunicipal sludge compost curing time onsuppression of Pythium and Rhizoctoniadiseases of ornamental plants. PlantDisease1988;72(9):751-756.

5 Hoitink HAJ, Grebus ME. Status of biolog-ical control of plant diseases with composts.Compost Sci. and Util. 1994;2(2): 6-12.

6 Kaplan M, Noe JP, Hartel PG. The role ofmicrobes associated with chicken litter insuppression of Meloidogne arenaria. J.Nematology. 1992;24(4): 522-527.

7 Schnurer J, Rosswall T. Fluorescein diac-etate hydrolysis as a measure of total micro-bial activity in soil and litter. Appl.Environ. Microbiol. 1982;43:1256-1261.

8 Seekin B. Field test for compost maturity.Biocycle 1996;9:72-75.

9 Workneh F, Van Bruggen AHC,Drinkwater LE, Shennan C. Variables asso-ciated with a reduction in corky root andPhytophthora root rot of tomatoes inorganic compared to conventional farms.Phytopath. 1993;83: 581-589.

10 Boehm MJ, Hoitink HAJ. Sustenance ofmicrobial activity in potting mixes and itsimpact of severity of Pythium root rot ofpoinsettia. Phytopath. 1992;82:259-264.

11 Lumsden RD, Lewis JA, Millner PD. Effectof composted sewage sludge on several soil-borne pathogens and diseases. Phytopath.1983;73(11):1543-48.

26

I N F O R M A T I O N B U L L E T I N

Organic growers generally use covercrops in conjunction with diversetypes of organic fertilizer materi-

als for fertility management. While covercrops are an economical source of organicnitrogen and provide additional potentialbenefits for succeeding crops, time or mar-ket constraints and the need to intensivelyfarm high value land may limit the use ofcover crops and increase the need to utilizeorganic fertilizer sources of plant nutrients.

Compost is often the most economicalsource of pre-plant applied nitrogen, butvarious factors may limit application ofcompost as a sole source of nitrogen, andother organic fertilizer sources may bemore convenient for side-dress or fertiga-tion. Several types of commercially avail-able nitrogen fertilizer materials areapproved for organic certification but littleinformation exists on their optimal man-agement. Little data is available comparingorganic fertilizer materials, different modesof application, and economical use fordiverse organic vegetable crops.

Costs per unit nitrogen of organic fer-tilizer materials can vary widely; fromapproximately $1 per pound of nitrogenfor compost to $51 per pound of nitrogenfor some liquid organic fertilizers. Greaterthan 50 fold differences in price per unitnitrogen are quoted for different organicfertilizer materials from commercial supplysources.

Project Objective■ To develop data on soil nitrogen

dynamics and bell pepper yield inresponse to the application of differenttypes of commercially available organicnitrogen fertilizers.

We conducted the trials on bell peppers,a long-term annual vegetable crop requir-ing repeated fertilizer application. We com-pared different rates of pre-plant incorpo-rated application combined with varyingadditional amounts of side banded, incor-porated applications. We measured weeklysoil nitrate nitrogen (SNN), plant tissuenitrogen, and bell pepper fruit yield associ-ated with the different types of organic fer-tilizers at different application rates.

Materials and methodsWe evaluated seven different organic nitro-gen fertilizers during the summer of 1998on transplanted bell peppers. The trialswere conducted at Nojoqui Farm in SantaBarbara Co. near Buellton, CA. The mate-rials evaluated are summarized in Table l.

Each material was applied at rates equiv-alent to 60, 120 and 180 lbs of N (as com-mercial product) per acre. Treatments werereplicated four times. Field plots consistedof three 40” beds, 20 feet long. Treatmentswere applied to all three beds in a plot butSNN and yield samples were taken from

the center beds only, and thus werebuffered from neighboring treatments. Alltreatments were applied by hand and sub-sequently incorporated with a cultivator.Pre-plant applications were applied asbroadcast applications which were subse-quently incorporated and side-dress appli-cations were applied in 6” wide bands 2” -4” to the side of plant rows and incorporat-ed with cultivating shoes. All plots weresprinkler irrigated.

The materials were applied as:• 60 lb total N treatment: 30 lb N pre-

transplant (PRE) and 30 lb N at 20 dayspost transplant (POST);

• 120 total lb N treatment: 60 lb N PREand 30 lb N at 20 days POST and 30 lbN at 40 days POST;

• 180 total lb N treatment: 60 lb N PRE,30 lb N at 20 days POST, 45 lb N at 40days POST, and 45 lb N at 70 daysPOST.

The PRE treat-ments wereapplied May 1;side-dress onewas applied June1, side-dress twoon June 20 andside-dress threeon July 20,1998. Bell pep-pers were trans-planted on May14 and the initialSNN samplingwas made attransplanting.

To measureSNN, trowel samples were taken down therow and mixed into a small bucket fromwhich the composite sample in each plotwas drawn. Samples were transported tothe laboratory where they were extractedusing 2N KCL according to standard pro-cedures. The KCL extracts were sent to theDivision of Agriculture and NaturalResources (DANR) laboratory at theUniversity of California-Davis for nitratenitrogen determinations.

Efficient Use of Organic Nitrogen FertilizersMark Gaskell

(7-0-0)

Seabird guano

MaterialManufacturer/

Source

AdvertisedAnalysis

(% N-P-K)

Cost($/lb N)

Compost New Era (2-1-3) 1.00

Pelleted chicken Integro (3.5-1-7) 6.50

Fish meal Peaceful Valley (10-6-2) 5.50

Liquid fish EcoNutrient (3.4-2-0.5) 6.00

Phytamin 800 (liquidsoybean meal formula)*

California Organic/Peaceful Valley

7.50

Feather meal California Organic (7-1-7) 5.50

Verditech (11-8-2) 6.25

Table 1. Organic fertilizer materials, manufacturer, advertisedanalysis, and estimated cost per unit nitrogen.

Principal investigator:Mark Gaskell, Farm Advisor, UC-Cooperative Extension, Santa Maria, CA

Collaborators:Helmut Klauer, General Manager,Nojoqui Farm, Buellton, CA

James Witty and Derek Markolf:laboratory soil extractions,field sampling

OFRF support: $4,840

Additional support: laboratory facilitiesprovided by CalPoly Soils Department

Project period: 1998-1999

RESEARCH REVIEW

*Phytamin 800 ingredients have changed since this project took place.

27

W I N T E R 2 0 0 1 N U M B E R 9

ResultsWe measured weekly soil nitrate nitrogen(SNN) over 14 weeks POST, leaf tissue Nat week 14, and fresh bell pepper fruityield for all treatments. Overall, there wasfrequently a statistically significant increasein SNN with increasing N applicationrates with each material during a givenweek. Weekly SNN varied from lows of 4PPM in the 0 N treated plots to over 80PPM in feather meal treated plots at the180 N rate. Highest SNN was oftenobserved in plots treated with feather meal,seabird guano, Phytamin 800, liquid fish,and feather meal at the 180 N rate. Peaksin SNN lagged fertilizer applications bythree to four weeks.

Plant tissue N also increased with increas-ing N application rates, but these increaseswere only statistically significant with feath-er meal and seabird guano (data notshown). Total pepper yield increased withincreasing N rate with all materials. The dif-ferent types of materials, while not marked-ly affecting total pepper yield, did affectearly yield and size. Early yield and percentextra large peppers were the yield traits thatvaried most among the different fertilizermaterials. Highest early yield and largestsizes were observed in feather meal treatedplots at the high (180 lb N) rate. The high-er early yields and the larger peppers tendedto come from those materials such as feathermeal, seabird guano, Phytamin, liquid fish,

and fish meal, that had shown higher SNNmany weeks. Compost and pelleted chickenmanure consistently showed the lowestSNN levels at all levels of applied N.Compost and pelleted chicken manure alsoproduced fewer peppers than the othermaterials even at the highest N rates.

Weekly SNN, tissue N and yield were allanalyzed using analysis of variance(ANOVA) and simple linear regressionanalyses. The SNN values are generallyquite variable in field soils and four repli-cations are the minimum necessary to getreasonably consistent results. The weeklySNN frequently showed statistically signifi-cant regression lines with increasingapplied N in each treatment. The relation-ship between SNN and applied N arenever extremely close however, as evi-denced by correlation coefficients rangingup to 65-70%. The correlation coefficientsof SNN on N rate are not always statisti-cally significant across weeks although themeans tend to follow similar patterns. TheSNN levels from the individual treatmentscould be distinguished with 95% confi-dence some weeks but confidence intervals(95%) around the regression lines oftenoverlap due to the high variability. Thetotal harvested yield is not significantly dif-ferent (P>0.05) among the fertilizer mate-rials. Differences in extra large pepper yield(Table 2) and early pepper yield are moreuseful for identifying the more promisingfertilizer materials.

Discussion and ConclusionsFigures relating SNN to optimum cropproductivity quoted in the scientific litera-ture typically range from 20 to 40 PPMnitrate nitrogen, but little specific data isavailable for bell peppers or for weeklySNN variability. Results from these trialsshow higher SNN was associated withhigher N application rates with each of thefertilizer materials but even at the highestrates, SNN values do not consistentlyremain in the range of 20-40 PPM. Thismay mean that N application rates higherthan 180 lbs N per acre are necessary foroptimum yield. Higher N rates would besuggested by the fact that highest yieldsoccurred in these trials at the highest Napplication rates although differences werenot always statistically significant. Theweekly SNN varied markedly among thematerials, and in the consistency of theirresponse (statistical significance).Treatments that frequently showed higherSNN, such as feather meal and seabirdguano, also were the only materials toshow statistically significant tissue N asso-ciated with applied N. Only feather mealstands out in terms of bell pepper yieldand then only related to larger pepper sizesand higher early yield. Yields of extra largeand early peppers can be importantbecause these typically carry a sales pricepremium.

The lack of consistent statistically signifi-cant (P< 0.05) differences among treat-

Seabird guano

Material

Feather meal

X-Large pepper yield(lbs / plot)

23.7 a

Phytamin 800 17.1 ab

Liquid fish 16.8 bc

Fish meal 16.7 bc

16.1 bc

Compost 14.9 bc

Pelleted chickenmanure

11.3 bc

Table 2. Statistical mean separation ofextra large grades of bell peppersfertilized with 180 lb N per acre of thedifferent fertilizer materials.

Values followed by the same letter are notsignificantly different (95% confidence)using Fisher’s LSD.

405060708090

100

Soil

Nit

rate

Npp

m)

Fig. 1. Weekly residual soil N03-N following application of different organic soilamendments, at 180 lb N application rate. Buellton, CA. 1998.

28

I N F O R M A T I O N B U L L E T I N

ments is not unusual with a variable suchas SNN in field soils. However, the rela-tionships and trends are consistent amongmaterials and rates across weeks and thisadds to the value of the data. More addi-tional study is certainly needed. BecauseSNN and yield are highest at the highestapplication rate it would be valuable toevaluate even higher rates of applied N. Itwould also be valuable to evaluate the pat-terns associated with application of thesematerials during cooler cropping periods.

An economic evaluation of the differentmaterials was conducted at the highest Nrate. This evaluation compares gross dollarvalue of peppers produced (beyond thezero plot yields) per dollar of fertilizerapplied. It uses average figures for the dif-ferent treatments and assumes 50 cents apound for peppers for the total marketableyield and 75 cents per pound for the earlyyield plots. These figures were consistentwith Nojoqui Farm’s prices during the1998 pepper sales season. These economicanalyses are summarized in Figure 2.Compost treated plots at 180 lb N pro-duced highest gross economic return perfertilizer dollar, because the compost hadsuch a dramatic cost advantage over theother materials. The lower productivity ofthe compost overall was overwhelmed inthe economic analysis by the dramatic costadvantage for compost. In this economic

analysis we assumed that compost was 2%N (as advertised), 25% moisture, and cost$40 per ton applied. The compost is vari-able however, and cost per unit value of Nfor compost may vary. The economic com-parison may be dramatically affected bycost and composition of the materials.Further study is needed with differenttypes of management of compost as a fer-tilizer material. It is unclear whether it maybe possible to manage compost material insuch a way so as to attain the levels ofSNN apparently necessary for optimumbell pepper yield and size.

The variability in composition of organicfertilizer materials is a serious problem lim-iting their efficient use, but of coursegrowers cannot be expected to analyzeevery material coming on to the farm.Ideally the data presented here and thesetypes of trials will provide an additionaltool for growers to more effectively choosebetween and utilize these materials. We areonly beginning to get reliable scientificdata to guide efficient and effective use ofthese and other important organic fertilizermaterials.

There is an important role for greenmanure crops to fill depending upon thecropping intensity of a given farm opera-tion. And economics will only be one ofmany key factors considered in developingfertilization and soil building strategies.

There are other potential problems associ-ated with the long-term, heavy use of com-post as would be necessary in an intensiveorganic production environment. Clearlymany other factors need to be consideredin the development of a comprehensivestrategy for optimum nitrogen manage-ment in an organic production environ-ment.

ReferencesAdamiak J, Adamiak E. The effect of different formsof organic fertilizer on yield and quality of sugarbeet.Zeszyty-Naukowe-Akademii-Roiniczej-w-Szczecinie,-Rolnictwo.(Pol) 1996;62:38.

Dominguez-Gento P. Accumulation of nitrates in let-tuces grown using organic fertilizer. Alimentaria1994;31(251):79-80.

Hadras A., Rosenberg R. Guano as a nitrogen sourcefor fertigation in organic farming. Int-J-Fert-Use-Technol. Dordrecht 1992;31(2):209-214.

Hsieh CF, Hsu KN. Effect of organic manures on thegrowth and yield of sweet pepper. Bulletin- TaichungDistrict Agricultural Improvement Station.1994;(42)1-10.

Leclerc B, George PL, Cauwel B, Lairon D. Organicfertilizer nitrogen mineralization rates. In:Agricultural alternatives and nutritional self-sufficien-cy for a sustainable agricultural system that respectsman and his environment. Proc. of the IFOAMSeventh lnt Scientific Conference, Ouagadougou,January 2-5, 1989. Ekopan, c. l990; 317-329.

Maynard AA. Intensive vegetable production usingcomposted animal manures. Bulletin Connecticut-Agricultural-Experiment-Station. 1991;No. 894,13 pp.

Munoz MA, Colberg O, Dumas JA.. Chickenmanure as an organic fertilizer. J. Agric.Univ. PR. Rio Piedras, P.R. : University of PuertoRico, Agricultural Experiment Station.1990;Vol74.(2)139-144.

Smith SR, Hadley P. Nitrogen fertilizer value of acti-vated sewage derived protein: effect of environmentand nitrification inhibitor on NO-3 release, soilmicrobial activity and yield of summer cabbage. Int J-Fert-Use-Technol. Dordrecht 1992;33(l) 47-57.

Zaharah A, Vimala P, Zainab RS, Salbiah H.Response of onion and shallot to organic fertilizer onbris (Rudua series) soil in Malaysia. Acta-hortic.Wageningen 1994;358: 429-432.

❁

The full report for this project (Project #98-04) is16 pages and includes 17 figures and two tables.The report is available by mail from OFRF or byvisiting our website at www.ofrf.org. OFRFrenewed funding for this project in 2000; furtherproject results will be reported in a future editionof the Information Bulletin.

0

5

10

15

20

25

Add

itio

nalG

ross

Ret

urn

onPe

pper

sPe

rD

olla

rof

Fert

ilize

r($

)

Compost Fish meal Liqfish Phytamin

Fig. 2. Additional return on early harvested (first and second pick) bell peppersfollowing application of varying types of organic fertilizers at 180 lb N per acre.Assume $0.75 per lb peppers. Buellton, CA. 1998.

29

W I N T E R 2 0 0 1 N U M B E R 9

Dragon Mountain Farm has beengrowing and selling certifiedorganic lamb in the commercial

marketplace since 1993. We’ve had keeninterest from retailers and wholesalers forour product and have consistently under-supplied the market. We have been trou-bled by an increasing problem with inter-nal parasites that we have not been able tocontrol through grazingmanagement alone. Themanagement standards ofthe Certified OrganicAssociation of BritishColumbia allow us toworm our ewes with con-ventional products up tothe third trimester of ges-tation. However, thisdoes little to alleviate theworm problem in theoffspring, as the wormload in the ewes is alwayshighest during lambingand lactation. Grazingmanagement is the mostimportant tool in con-trolling internal parasites,and much worldwideresearch has been done on this. To date,we have not found a practical and effectivegrazing rotation pattern that will alleviatethis problem. Just as our well-managedorganic garden will sometimes need to besprayed with Bt, we are looking for aneffective worming method to complementother management strategies.

Objective■ To evaluate the anthelmintic (worming)

properties of four different substancesthat have been suggested to us througharticles or by other producers. By mon-itoring fecal samples and recordingrates of gain in the test animals, wewanted to see if any effect could befound.

MethodsOn July 24, 1998, we weaned lambs,which ranged in age from three to fourmonths of age, from our ewes. About tendays later, we selected 15 test lambs fromthis group. Post-weaning is when thelambs seem to be most susceptible toworm infestation or at least when theeffects are most noticeable, probably dueto the stress of weaning. We chose fromthe less thrifty lambs in the flock withweights ranging from 56 to 66 pounds.These lambs were randomly divided intofive groups as follows:

Group 1 - Control: Three lambs receivingno treatment at all.

Group 2 - Herbal: Three lambs receivinga commercially prepared herbal wormer

from Hoeggers Supply. This containswormwood, gentian, fennel, psyllium, andquassia. It was fed as per manufacturer’sinstruction at a rate of 1½ teaspoonsmorning and night for three consecutivedays. When mixed with grain, it was readi-ly consumed by the lambs.

Group 3 - Garlic: Three lambs receivingthree crushed garlic cloves each that wereadministered with a bolus gun to ensurethat it was consumed.

Group 4 - Diatomaceous Earth (DE):Three lambs receiving DE at the recom-mended rate of 2 percent by weight of feed

ration. They were fed this dailythroughout the trial with rolledbarley.

Group 5 - Pyrethrum: Threelambs receiving a drench con-taining pyrethrum. The recom-mended rate was 3.5 mg/kg ofbody weight of 0.8 percentpyrethrum. This concentrationof pyrethrum was not available,so we calculated the rate usingTrounce insecticide, which con-tains 0.2 percent pyrethrum, toobtain the same dosage. Theselambs received one initial doseand two subsequent doses.

The sample size made it prac-tical for us to test several agents.We were looking for strong indi-

cators to point towards further investiga-tive possibilities.

The lambs in four of the treatmentswere pastured together on second-cropgrass, clover, and alfalfa pasture. The DEgroup (Group 4) was kept alongside, butseparated by electric fence to enableadministration of the daily dose of DE andgrain. The other groups also received thesame one half pound of barley per day tokeep the rations even. Each lamb waspainted to identify its group and given anindividual number. Each lamb wasweighed and had a sample taken before thefirst treatment and was weighed and sam-pled four more times throughout the testperiod, which ended on September 21,1998. The lambs were moved every weekto clean pasture to avoid recontamination.

On August 11, one of the DE lambs

Testing Alternative Parasiticidesfor Organic Lamb ProductionJanet Allen

Principal investigators:Janet Allen, Murray Boal, PaddyDoherty, Dragon Mountain Farm,Quesnel, British Columbia

OFRF support: $3,284.00

Project period: 1999

Sheep and lambs on pasture at Dragon Mountain Farm.

RESEARCH REVIEW

30

I N F O R M A T I O N B U L L E T I N

appeared very ill with diarrhea. He hadmaggots in his taggy wool, so he wassheared and externally treated with flyspray. We added another lamb to Group 4at this point in case the sick one didn’trecover. The sick lamb recovered quickly,so we then put him back in the test. Fromthis point, we carried four lambs in Group4. Initially we thought the diatomaceousearth was responsible for his illness as theproduct seemed dusty and unappetizing;however, there was no reccurrence or inci-dence in any other lambs, and they con-sumed the grain mix readily.

On August 23 and September 7, theherbal mixture, the garlic, and thepyrethrum were re-administered to the tar-get groups. The DE, of course, was ongo-ing.

Data AnalysisFor this trial of several organic ovineanthelmintics, the fecal flotation diagnos-tic test was used. Fecal samples were mixedwith Fecasol, a commercial brand of flota-tion solution with a specific gravity of 1.2.Containers used were the Fecalyzer brandof diagnostic systems. Eggs were floatedfor 10 minutes; this time allowed a suffi-cient number of eggs to rise to the surfacewhile reducing the amount of deteriora-tion observed.

Observations were carried out using astandard light microscope. Slides werescanned first with the 4x objective forTrichostrongyloidea (Nematocera) eggs Theobjective was then switched to 10x forscanning of Moniezia (Tapeworm) eggsand roundworm eggs, Haemonchus,Ostertagia and smaller Trichostrongylusspecies were counted as roundworms. The

number of roundworms visible in severalmicroscopic fields was recorded, and if suf-ficient numbers were present, they wererecorded as “numerous.” At the beginningof the trial, the number of visible round-worm eggs needed to record a “numerous”result was 20 - 30 eggs. As the trial pro-gressed, and the roundworm densityincreased, the number needed to record a“numerous” went up to 30-50, or evenhigher! After roundworms, the objectivewas switched to 40x for a quick scan todetermine presence of Eimeria species.

Identification of parasite eggs was madeusing W.J. Foreyt’sVeterinary ParasitologyReference Manual, ThirdEdition.

Limitations ofDiagnostic MethodsThe fecal flotation testswere used to determinepresence or absence ofparasite infestation oflambs tested. Due to thefluctuating amount offeces available (not allsamples had a full quo-

tient; for example, some had scant diar-rhea), several samples would still test posi-tive for infestation, but when placed on agraph, would show a lower egg count. Onescant sample was further diluted by acci-dental spillage and refilling, yet stillshowed parasite presence (September 21).

ObservationsAll groups showed presence of round-worms at the beginning of the trial. Allgroups also showed a higher level ofroundworm presence at the end of thetrial. The only samples showing extremelylow levels of infestation were the three ran-dom flock samples tested on September 14(these had been dewormed with Ivomec, acommercial anthelmintic).

Figure 1 shows worm counts for round-worms. These are average counts for thelambs in each group. In doing the count,25 in one slide was considered verynumerous; it’s evident we are dealing witha significant infestation. Overall, no pat-tern or improvement can be seen in anyone of the samples from the different test-ings. In fact, the Control group, Group 1,

received no treatment at all for worms andended up with the lowest count overall forthis particular type of parasite. It should benoted, however, that even this rate is anunacceptable level of infestation.

Rate of GainActual weight gain averaged for each groupis plotted in Figure 2. These lambs were allgaining at a slower rate than the expectedrate of gain for a lamb with no infestation(lamb treated with Ivomec). The testgroups show the same curve as the controlgroup. After September, the high wormcounts took their toll as the lambs actuallybegan to lose weight. It should be notedthat drought conditions at this point werea contributing factor as pasture qualitydropped as well. Also note that theOctober 6 weight was recorded two weeksafter these lambs all went off test and weretreated with a commercial wormer.

Group 1 - Control: This group per-formed as well as or better than the groupsreceiving alternative wormers.

Group 2 - Herbal: This group receivingthe herbal preparation showed noimprovement throughout the study. Whilemuch anecdotal evidence exists about itseffectiveness, we have not seen any meas-urable data to contradict the findings inour study.

Group 3- Garlic: This group initially hadthe best rate of gain from the five groups.Perhaps garlic stimulates the appetite, butit showed no effect on fecal worm countsor overall performance.

31

W I N T E R 2 0 0 1 N U M B E R 9

Group 4 - Diatomaceous Earth: Thisgroup receiving. DE showed no improve-ment throughout the study. DE is themost commonly touted natural wormerand is often advertised as a natural wormcontrol agent. Our findings support thoseof previous studies in that no effectivenesscould be measured.

Group 5 - Pyrethrum: We feel our find-ings are the least conclusive here. While noeffectiveness was demonstrated in ourstudy, we feel pyrethrum should be re-tri-aled with a purer product, perhaps at a

stronger rate. Our dosage was basically aneducated guess; and while no positiveresults were seen, it perhaps was not fullyexplored. Working closely with a veterinar-ian to determine the proper product anddosage should be pursued before this prod-uct is ruled out.

Overall, these lambs were subject to aheavy parasite challenge; and while itwould perhaps be unrealistic to expectthese alternative wormers to eradicate theproblems, if they were at all effective, somepositive dip in count numbers or improve-

ment in rate of gain should have beenobserved.

We pastured these lambs together so thatthey were subjected to the same condi-tions. As these lambs were moved to freshpasture regularly, we don’t think that cross-reinfection was a significant problem. Ifthere were any effectiveness at all in thesealternative wormers, it should have beendemonstrated by either rate of gain or fecalegg counts.

ConclusionOur study failed to show any effectivenessin any of the tested alternative wormers.At this point, none of them show any use-fulness as part of a management strategy indealing with internal parasites in sheep. Asthese substances are commonly recom-mended among organic livestock produc-ers, it is disappointing that noanthelmintic properties could be demon-strated.

However, our study has been extremelyuseful to us. We feel that it stresses theneed to systematically assess the usefulnessof any alternative wormer. If there are sub-stances out there that could be part of alivestock management plan for dealingwith internal parasites, we need to measuretheir effectiveness objectively.

In Britain, where much of the organicmanagement research has been done onsheep, commercial wormers are stillallowed, where necessary, in the organicstandards. While we research and test cer-tifiable, safe, effective alternatives, we feelthe British model is a sensible approach.

We are extremely interested in commu-nicating with any producers or researcherswho are keen to pursue this line of inquiry.

❁This project report (Project # 98-03) hasbeen presented in its entirety. Project investi-gators may be reached at Dragon MountainFarm, Box 31, Bastin RR #7, Quesnel, BC,Canada V2J 5E5.

0

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3-Aug 16-Aug 28-Aug 14-Sep 21-SepDATE

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Fig. 1. Rate of roundworm infestation in lambs treated with alternativeanthelmintics. Quesnel, BC, 1999.

Fig. 2. Rate of weight gain in lambs treated with alternative anthelmintics; alterna-tive treatment and control lambs received conventional wormer on September 21.Quesnel, BC, 1999.

I N F O R M A T I O N B U L L E T I N

Non-ProfitOrganizationU.S. PostageP A I D

Permit No. 616Santa Cruz, Ca.

ORGANIC FARMINGRESEARCH FOUNDATION

I N F O R M A T I O N B U L L E T I N

P. O. B o x 4 4 0 S a n t a C r u z , C a l i f o r n i a 9 5 0 6 1

R E T U R N S E R V I C E R E Q U E S T E D

Fall 2000 Grants:Organic apple crop thinning strategies.Curt Rom, University of Arkansas,Fayetteville, AR $7,442

Evaluating corn varieties for organiccrop production.Phil Rzewnicki, Ohio State University,Columbus, OH $8,280

OFRF awards grants for organic farmingresearch and education projects twotimes per year. Grant application dead-lines are January 15 and July 15.Projects may be farmer initiated, and/orshould involve farmers in project designand execution and take place on organicfarms, whenever possible. OFRF consid-ers funding requests within the range of$1,000 to $10,000.

We marked our ten-year anniversary thisfall by awarding a record level of researchfunds. Over $82,000 in competitivegrants was funded this fall, bringing theyear's total to $150,500 in grants made.

To obtain our Procedures for GrantApplications, please contact OFRF at:tel. 831-426-6606, or visit our website atwww.ofrf.org.

Integrated caterpillar control in organicsweet corn (Year 2).Ruth Hazzard, Universityof Massachusetts, Amherst, MA $9,285

Use of Metarhizium anisopliae (Agassizstrain) as a microbial control forwireworms.Todd Kabaluk, Pacific Agri-Food ResearchCentre, Agassiz, B.C., Canada $5,805

Effects of organic alternatives for weedcontrol and ground cover managementon tree fruit growth, development, andproductivity.Steve Ela, Silver Spruce Orchards,Hotchkiss, CO $7,680

Evaluation of kaolin-based particle filmcoatings on insect, disease, and heatstress suppression in apples (Year 2).Andrew Thomas, University of Missouri,Mount Vernon, MO $4,171

Increasing organic farmer access torelevant and practical research-basedinformation.George Kuepper, Appropriate TechnologyTransfer to Rural Areas (ATTRA),Fayetteville, AR $4,500

Long-term organic farming impacts onsoil fertility.Jessica Davis, Colorado State University,Ft. Collins, CO $5,548

Bat houses for integrated pestmanagement.Mark Kiser, Bat ConservationInternational, Austin, TX $5,800

Improving the quality of organic herbproduction and marketing.Kathleen Delate, Iowa State University,Ames, IA $5,500

Biological control of Delia sp. in colecrops with rove beetles, Aleochara sp.(Year 2).Renée Prasad & Deborah Henderson,E.S. Cropconsult, Vancouver,B.C., Canada $5,600

Green manure and weed mat impacts onsoil biota and tree growth in organicpeach orchards.Rick Zimmerman, Rogers Mesa ResearchCenter, Hotchkiss, CO $4,000

Comparing antibiotic susceptibilitypatterns for Staphylococcus aureus inorganic and traditional dairy herds.Ynte Schukken and Linda Garrison,Cornell University, Ithaca, NY $8,500

Effectiveness of compost extracts asdisease suppressants in fresh marketcrops (Year 2).Sylvia Welke, Wild Flight Farm,Mara, B.C., Canada $2,900

Grants Awarded