Season Extension and Weed Management: High Tunnels and Biodegradable Mulches

Carol Miles, Vegetable SpecialistJeremy Cowan, Ph.D. Student

Department of HorticultureWSU Mount Vernon NWREC

Biodegradable Mulches for Specialty Crops Produced Under Protective Covers

Debra Inglis and Carol Miles (Project Directors)1;Andrew Corbin, Jessica Goldberger, Karen Leonas, Tom Marsh and Tom Walters1;

Doug Hayes, Jaehoon Lee, Larry Wadsworth and Annette Wszelaki2; Jennifer Moore-Kucera3; Russ Wallace4; Marion Brodhagen5 ; and Eric Belasco6;

1 25

SCRI Grant Award

No. 2009-51181-05897

43 6

SCRI Project Goals for High Tunnels

Assess agricultural and economic impacts of using high tunnels as compared to open field for tomato, lettuce and strawberry production

Compare performance of biodegradable mulch (BDM) in high tunnel and open field

Compare high tunnel structures in three diverse locations in the U.S. with focus on wind tolerance and labor requirements

Nanjing Agricultural University, Nov 11

DefinitionsDegradeMeasurable conversion of C to CO2 through abiotic factors such as heat, UV light, or mechanical stress.

BiodegradeBreak down via microbial activity; ultimately the oxidation of the parent compound to carbon dioxide and water, providing carbon and energy for the growth and reproduction of cells.

DeteriorateLoss of physical or mechanical strength as observed through physical testing, microscopic imaging or visual assessment.

Field Experiments Variety trials: 6 cvs tomato; 6 cvs lettuce; 6 cvs strawberryBDM trial: with tomato cv. CelebrityLocations: Mount Vernon WA, Lubbock TX, Knoxville TN

Experimental design:• Randomized complete block with four replications • Main plot: high tunnel and open field• Subplots: 3 feet wide bed, 14 feet long• BDM planted with tomato • Plots managed organically

BDM experimental treatments: 1) Experimental fabric – SB-PLA2) BioBag – starch-based (Mater-bi®) film3) BioTelo – starch-based (Mater-bi®) film4) Sunshine paper – cellulose, 100% degradable 5) Standard black plastic – PE, 1.0 mil embossed6) Bare ground / non-mulch control

High tunnels provide: • Increased heat • Protection from rainfall• Reduced leaf wetness • Increased crop yield • Shortened time to harvest for many crops

Mount Vernon, WA Lubbock. TX Knoxville, TN

  Mount Vernon, WA Lubbock, TX Knoxville, TN

  HT OF HT OF HT OF

GDDy (base 10 oC) 1007 740 1799 1661 1795 1463

Ave. daily max. air temp. (oC) 24.2 21.1 31.9 32.6 34.2 33.5

Ave. daily min. air temp. (oC) 10.5 9.7 24.7 18.9 17.5 18.7

Ave. soil temp at 5 cm depth            

BioBag 18.9 17.7 26.2 25.6 26.2 27

BioTelo 19.3 18.1 25.9 26.6 27 26.8

SB-PLA-10 18.7 17 24.9 24.6 26.5 26.6

Weed Guard Plus 18.3 16.7 26.9 26.6 25.7 26.3

Black Plastic 19.8 18.9 27.2 28.2 27.8 27.3

Bare Ground 18.7 16.8 24.9 25.2 26.9 26.7

Ave. sol. rad. (µmol·m-2·s-1) 0.36 0.44 0.35 0.54 0.41 0.57

Relative Humidity (%) 79.7 81.3 66.2 66.7 74.1 79.2

Ave. wind speed (km·h-1) 1.1 3.3 0.2 6.4 0 1.9

Total rainfall (mm) 0 235.5 NA 333.5 0 156

Climate Comparison for HT and OF - 2010

Tomato Yield High Tunnel and Open Field at Mount Vernon 2011

Total Number (plot-1) Total Weight (kg.plot-1)

Lettuce Yield High Tunnel and Open Field at Mount Vernon in 2011

Total Weight (kg.plot-1) Marketable Weight (kg.plot-1)

Plastic mulch provides: • Weed control • Conservation of soil moisture • Increased crop yield • Modified soil temperature• Shortened time to harvest for many crops

Plastic mulch must be removed from the field for disposal; in-field incorporation and

biodegradation would eliminate disposal costs

Rick Boydston, USDA ARS

Biodegradable mulch generally made from:• Poly(lactic) acid (PLA)

- plant-based polyester produced from starch

• Polyhydroxyalkanoates (PHA)-polyesters produced by bacterial fermentation of sugar or lipids

Skeletal formula of poly(lactic) acid Bacillus subtilis poly-(R)-3-hydroxybutyrate

Andrew Corbin, WSU Extension

Presumed Mulch (Bio)Degradation

Doug Hayes, UTK

SCRI Project Goals for Biodegradable Mulches

Assess agricultural, ecological, and economic consequences of using biodegradable mulches in high tunnels and open field

Test PLA-based spunbond as mulch prototype

Compare PLA and commercial “biodegradable” mulches for performance in growing tomatoes

Provide data that may be useful for developing an ASTM standard for biodegradation of mulches in soil

Nanjing Agricultural University, Nov 11

CollaboratorsNature Works (U.S.), Saxon Textile Research Institute (Germany), and GreenBio (China)

Experimental PLA mulch for field testingSB-PLA-10 high MW, whiteSB-PLA-11 half MW of (10), small fiber size, blackSB-PLA-12 blended with PHA (20%), black

SCRI Project Experimental BDM

September 23, 2010Mount Vernon

Open field

High tunnel

Weed Control with Biodegradable Mulch High Tunnel and Open Field, Mount Vernon 2010

Total Number (plot-1) Total Weight (g.plot-1)

Tomato Yield with Biodegradable Mulch High Tunnel and Open Field, Mount Vernon 2011

Total Number of Fruit (plot-1) Total Weight of Fruit (kg.plot-1)

Mean Tomato Fruit Quality with MulchesHigh Tunnel and Open Field, Mount Vernon 2011

Supported by CSANR BIOAg grant

Fruit oBrix Fruit % Acidity

Mulch Visual Evaluations

Two times each month measure: Number of rips, tears and holes (RTH) Percent visual deterioration (PVD)

BioBag: 6/17/11 8/1/11 9/2/11 10/10/11

BDM Percent Visual DeteriorationHigh Tunnel and Open Field 2010

Mount Vernon and Knoxville

Mulch - Laboratory TestingFirst Flower

SB-PLA-10 SB-PLA-11

BDM Sample PreparationFirst Flower

BioTeloBioBag

BDM Sample Degradation

Planting

Final Harvest

BioBag BioTelo

Karen Leonas, WSU

BDM % Maximum Load at Final Harvest2010 HT and OF at Mount Vernon, Lubbock & Knoxville

Open Field High Tunnel

Doug Hayes, UTK

Mesh Bag Study Mount Vernon 2011

Oct 2010 BB TX Mar 2011 BT TX Mar 2011

Jennifer Moore-Kucera, TTU

Current Status

Year 2 field studies complete; data are being entered and analyzed

Year 1 and Year 2 preliminary reports posted on Team website http://mtvernon.wsu.edu/hightunnels/

Year 1 results are being submitted for publication Winter 2011

Developed a team website and public website for information sharing