INTERNATIONAL SIMPOSIUM

1996

A BIOLOGICAL-DYNAMICAL PATTERN OF FERTILIZATION

ON DROPWISE IRRIGATION SYSTEMS

Mr. Ronald R.Cass Technic Director

NEW EEZV-GRO IMC. 11.51

s i m p o s i u m i n t e r n a c i o n a l 1996

R O N A L D A . C A S S

T E C H N I C A L D I R E C T O R

V I C E P R E S I D E N T E O F M A R K E T I N G

N E W E E Z Y O R O INC.

The B i o l o g i c a l l y D y n a m i c M o d e l of soi l Fertility

says that soi l l i fe is bas is for soil fertility. The

grater the quantity and variety o f l i fe growing

and f e e d i n g in and on the soi l , better its fertility.

The impl icat ions o f this approach to soil fertility

are substantial. M a n a g i n g a total farming s y s t e m with the

B io log ica l ly D y n a m i c M o d e l as the gu id ing principles can

mean s igni f icant ly h igher y ie lds , m u c h less d i s ease and

insect pressure, plus improved overall quality of the entire

crop. It can lead to e l iminat ion of such cost ly practices as

fumigat ion and to reduced irrigation rates.

D E F I N I T I O N O f II F E R T I L E S O I L

The soi l should a l w a y s be v i e w e d as a l iv ing

thing, a sys tem that funct ions wel l only w h e n the needs o f

all its c o m p o n e n t s are cared for. Al l soi l practices should be

v i e w e d on the basis o f whether or not they promote a rich,

diverse soil l i fe and create a rich biodiversity a b o v e the

ground. We can c h o o s e to cooperate with natural patterns

or attempt to dominate them, but only cooperat ion with nat-

ural patterns can bring truly ferti le soil . Understanding that

a truly fertile soi l is o n e w h i c h is b io log ica l ly dynamic ,

which in its root words m e a n "l iving powerful ly", a l l o w s us

to create a healthily bas is for all l i fe .

/ / A soil isn't ferti le because it contains large

' ' / % a m o u n t s o f h u m u s or minerals or nitro-

/ 1 g e n , but b e c a u s e o f the c o n t i n u o u s

i ^ t ^ L growth o f numerous and varied microbes

and soil l ife w h i c h break d o w n and reconstruct nutrients

from organic matter suppl ied by plants and animals into

plant-available form. T h e populat ions of soi l l i fe benef i t us

s i m p o s i u m i n t e r n a c i o n a l 1996

bay m a k i n g minerals p lant-avai lable , bui lding humus,

building s l imes and the c r u m b structure o f soil . A soil

teaming with varied f o r m s o f l i fe is an exce l lent growth

environment for plant r o o t s — S i e g f r i e d Lubke ".

We need to understand natures laws so that w e can

work in harmony w i t h them. M u c h of our current farming

technique attempts to o v e r w h e l m and defeat nature with

intense ti l lage and tox ic chemistry . There are two typical

response curves to more intens ive fertil izer and chemicals .

First, net returns rise rapidly as the first f e w pounds are

added, until the " m a x i m u m e c o n o m i c yie ld" point is

passed. Th i s is w h e r e the "law o f d iminishing returns"

c o m e s in to force and the e f f e c t s o f s e c o n d response curve

is seen. O v e r m a n y years , that m a x i m u m e c o n o m i c yie ld

drifts l o w e r as our convent iona l fertility and chemical pro-

grams o x i d i z e and so lubi l i za soi l humus , destroy soil tilth

and gradually lower crop y i e l d s an quality.

Convent ional fertility practices are based upon the

"NPK" Theory o f Soi l Fertility, w h i c h in e s s e n c e says that

the amount o f minerals in a soil is what makes it fertile.

This l imited, m o r e narrow view, holds that soil

fertility should be v i e w e d as a statistical summary o f the

mineral e l e m e n t s f o u n d in soi l . This is a v i e w which states

that the process for increas ing fertility and y ie lds is to s im-

ply add the minerals w h i c h are def ic ient and replace those

taken away by cropping.

S imple l o g i c ho lds that y o u can analyze the pro-

duce o f an acre and return the nutrients for a maintenance

fertility program, or y o u c o u l d add a little more and have a

"build-up program".

N P H T H E O R Y IN Q U E S T I O N

The N P K Theory

is b e i n g q u e s -

t ioned increas -

ingly, particular-

ly in l ight o f the m o s t

a d v a n c e d t e c h n o l o g i c a l

a p p r o a c h e s w h i c h are

be ing used to monitor and

corre la te "fert i l i ty" and

y ie lds . Global Pos i t ioning

S y s t e m s ( G P S ) use c o m -

puters and sa te l l i t e s to

c h e c k y i e lds in comparison

with grid soi l test ing o f

N P K fertility. Th i s v i e w

says y o u can "fix" soi l s

wi th variable-rate applica-

tion o f N P K , if y o u just

k n o w where the analys is is

o f f .

O n e o f the top

G P S experts in the United

States says this approach is

faulty. D o n Larson, presi-

dent o f Larson S y s t e m s ,

Inc. , A m e s , Iowa, S a y s ,

"We can' t find anything

farther f rom the truth".

Larson has worked c l o s e l y

with G P S techno logy on

"working" farms for years.

"We c o u l d not

s h o w any l inkage be tween

fert i l i ty l e v e l s and crop

product ion levels on a site-

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simpasium i n t e r n a t i o n a l 1996

spec i f i c basis . If anything, the h ighes t

y ie lds tend to c o m e on the areas testing the

lowes t in standard soil analysis", he said.

He w e n t on to say: "three factors

s h o w a corre la t ion b e t w e e n s o i l s and

yield":

1.- Organic matter. N o t necessari ly the

amount, but its b io logical activity.

2.- Water ho ld ing capacity and the proper

amount o f moisture.

3.- Ca lc ium leve l s an pH.

"If y o u don't have those three

parameters, y o u won' t raise top yie lds .

These are the only three i ssues where

w e ' v e found a correlation between comput-

erized soil maps and field maps from G P S

yield monitors . You cannot find that corre-

lation with convent ional fertility". (2)

A n O h i o farmer w h o used G P S

shares Larson's v i ews . M i k e Funderburgh

tried a y ie ld monitor with a satell ite-cor-

rected signal as part o f the 1995 Operation

Future field day on his farm. The biggest

surprise w a s comparing "fertility" with

yields. "The areas with the highest fertility

weren't the h ighest y ie lding, "he said. (3)

J a m e s Kinse l la , o f B A S F

Chemica l s Inc., reported that he found no

correlation b e t w e e n fertility and yie ld on

his farm w h e n he used G P S . In two sepa-

rate grid areas, on opposite corners o f the

f ie ld , y i e l d s w e r e virtual ly the s a m e ,

although the phosphate readings were 17

pounds per acre on one and 170 pounds,

ten t imes more , on another. (4)

A cons iderab le number o f field

research projects and d e m o n -

stration trials based on the bio-

logical mode l have been carried

out in the U S . and M e x i c o . A l s o , m a n y

farmers in the U S . and other countries are

adopt ing practices cons is tent wi th this

approach. W e i l e x a m i n e t w o o f these pro-

j ec t s as e x a m p l e s .

In M e x i c o over the past t w o years,

work has been d o n e with tomatoes grown

in soi l in greenhouse . In Jal isco, s ide -by-

s ide trial were conducted , us ing c o n v e n -

tional practicesin o n e area, and the b io log -

ical m o d e l in another. Resul t s were quite

encourag ing . Yie lds and quality in the bio-

logical area were the s a m e or grater as in

"convent ional" control area.

Soil preparation and type o f fertil-

izer materials were the t w o key d i f f erences

in h o w the crops were grown. In the con-

ventional area, soil w a s fumigated us ing

methyl bromide. In the b io log ica l area, n o

fumigat ion w a s done and in its p lace , d e e p

t i l lage ( 3 5 to 4 0 c m . ) w a s performed in

order to areate the soil with more o x y g e n .

A s the d e e p t i l lage w a s be ing a c c o m -

pl ished, several materials w h i c h aid in

increasing microbial l i fe were injected into

the soil . Th i s procedure w a s done 3 0 d a y s

prior to p lant ing . T h e mater ia l s u s e d

inc luded a s eaweed-based material w h i c h

conta ined l ive aerobic microbes , a

1

s i m p o s i u m i n t e r n a c i o n a l 1996

natura l ly -occurr ing c a r b o n s o u r c e to

enhance the rapid growth and reproduction

o f the microbes and i m m e d i a t e l y avai lable

source o f ca l c ium w h i c h a ides in microbial

growth , i m p r o v i n g so i l s tructure and

improving early growth of the plants.

Ferti l ization during the growing

season w a s d o n e by drip irrigation, wi th

typical granulated fert i l izers be ing dis-

so lved in water to provide nutrients for the

convent ional plot. In the b io log ica l m o d e l

plot, high-purity Liquid ferti l izers with low

salt indexes w e r e f ed through the drip irri-

gation sys tem.

The full s eason trials were con-

ducted from transplanting until final har-

vest and c o v e r e d a period o f about eight

months . Fruit qual i ty and y i e l d s were sta-

tistically equal . Virtually no inc idence o f

d i s e a s e o c c u r r e d in e i ther p lo t and

pathogen s c r e e n s s h o w e d no nematode

infestation. It is expec ted , based upon other

results, that overall y i e l d s and quality wil l

increase e a c h y e a r as o r g a n i c matter,

humus and soi l l i fe are built up.

In addit ion to the trials descr ibed

above, tomato s e e d l i n g s are be ing germi-

nated and grown in trays us ing no fumi-

gants or f u n g i c i d e s . A c o m b i n a t i o n o f

active b io log ica l s and high-purity fertiliz-

ers is b e i n g used. Resu l t s s h o w that the

seedl ings reach readiness for transplanting

nine day earlier (21 d a y s vs . 31 d a y s ) w h e n

compared with the convent ional program.

Plants are healthier and more v igorous and

root s y s t e m s are more deve loped .

At transplanting, the conventional

root treatment has been replaced with a

mix ture o f act ive b i o l o g i c a l mater ia l s

which contain l iv ing microbes and nutri-

ents. Similar work has been d o n e over

the past two years on potato in Idaho, o n e

of the major potato-growing regions in the

U . S . T h e objec t ive there has b e e n to

demonstrate the viabil ity the viabil ity o f a

total sys tems approach in growing high-

y ie lds of quality tubers without the use of

fumigants and relatively high-salt fertil iz-

ers. S ide -By- s ide compar i sons o f conven-

tional an b io log ica l ly -based fertility pro-

grams completed under actual field-grow-

ing condit ions s h o w e d similar favorable

results as were a c h i e v e d in tomato in

M e x i c o . Fertilizer material were applied

through center-pivot irrigation, in-row at

planting and by fol iar feeding. Yie lds and

quality were g o o d in both areas an there

were no observed d i f ferences in d i sease

pressure an nematode infestation.

O B J E T I V E M E A S U R E M E N T OF S O I L Q U A L I T Y

The results achieved in the above-

named trials are based upon a

wider principle that is increas-

ingly be ing accepted and inte-

grated into the "agronomic" thinking o f

many scientists. The prest igious National

A c a d e m y o f S c i e n c e s , based in

Washington, D.C. , recently asked a basic

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s i m p o s i u m i n t e r n a c i o n a l 1996

quest ion: W h a t is "soil quality?" T h e y

found that the answer depends m u c h more

on abundance of soi l l i fe than on just its

chemica l properties. T h e A c a d e m y cal led

for new ef forts to enhance soil quality as a

foundat ion for enhancing the environment .

A g r o n o m i s t s w h o now s e e soil as

a l iv ing environment are document ing the

links b e t w e e n healthy so i l s and nutritious

crops . T h e current generat ion o f

agronomists is looking for w a y s to objec-

tively quant i fy soil quality. Denn i s Keeney,

d irector o f the L e o p o l d Center for

Sus ta inab le Agricul ture B a s e d at I o w a

State Univers i ty has said: "The explorat ion

o f soil quality concepts has opened an

e x c i t i n g n e w d i m e n s i o n o f susta inable

agriculture.^"

Here's a partial list of object ive

soil quality measures w h i c h are be ing used:

1. Soil tests based upon solubility of nutrients in water, rather than acid

extraction agents , and soil tests based upon

mild extraction solutions. T h e s e tests c o m e

c lo ser to e s t imat ing what a plant can

extract. They aren't a "mining assay" o f

total nutrients in the soi l , whether they're in

an available form or not. T h e s e tests are

of ten used in conjunct ion with more con-

ventional , acid-extraction tests.

2. Available calcium ratios in comparison with other cat ions w h i c h con-

stitute the "base saturation" o f a soil .

C a l c i u m , more than any other nutrient or

e l e m e n t , a f fec t s soil tilth, so i l -borne dis-

eases , plant health and microbial l i fe .^

3. The Formazan tests, and other

quick es t imates of b io log ica l activity in

soi l , are b e c o m i n g avai lable to track leve l s

o f microbes , fungus and other organ i sms in

the w e b o f soi l l ife.

4. Computer-recorded penetrome-ter grid maps o f w h o l e f ie lds , cont inued

over several years. The penetrometer mea-

sures soil hardness at each depth through

the root zone . A s soi l l i fe increases , soil

tends to c luster into l o o s e aggregates and

its dens i ty or hardness dec l ines .

5. Water-stable soil aggregates. T h e "crumb structure" o f each soi l type can

be measured with a ser ies o f s i eves . Nea l

Eash , former researcher at the U n i t e d

States Department o f Agriculture's nation-

al So i l Tilth laboratory at I o w a State

U n i v e r s i t y , n o w at the U n i v e r s i t y o f

Tennessee , s h o w e d h o w soil aggregates

increase as m i c r o l i f e m u l t i p l i e s . M o r e

microbes m e a n better tilth, better mois ture

retention, l e s s applied irrigation water and

less w i n d and water eros ion.

6. Humus content estimates. Not jus t raw "organic matter", but percent

h u m u s is an indicator o f soi l quality. There

are different ideas on h o w this m a y be

f }

s i m p o s i u m i n t e r n a t i o n a l 199B

accompl i shed; h o w e v e r o n e m e t h o d is the

Luebke humus test w h i c h beg ins with a

conventional organic matter test, adds a test

for humic ac ids and ca lcu la te s a ratio

b e t w e e n the t w o o n a s ca l e o f 1 to 100. The

intent of this test is to de termine if organic

matter is actually b e i n g converted to humus

and this can tell us m o r e prec i se ly than ever

before if carbon is b e i n g properly stored

and released in the soi l sy s t em. H u m u s will

contain about 5 6 percent carbon, as we l l as

other nutrients.

C O M P O S I T I O N OF S O I L S

The p l a n t - s o i l r e l a t i o n s h i p is

a m a z i n g l y c o m p l e x and the

m o r e w e learn about it, the more

w e rea l i ze h o w primit ive our

k n o w l e d g e is. It is not c lear today how

many e l e m e n t s or exac t ly h o w they interact

wi th so i l l i f e t o i n f l u e n c e plant l i f e .

H o w e v e r , e a c h day as m o r e sc ient i s t s

embrace the bas i s for the b io log ica l mode l ,

w e learn and understand m u c h more.

Soi l l i fe m a y be c lass i f i ed in three

main groups:

1. Aerobic soil l i f e w h i c h requires

air. This is the m o s t important group to

agriculture.

2. Faculative Anaerobic -Soil life that can live with or wi thout air.

3. Obligate Anaerobic - Microbes which d o not require air and are suppressed

by it.

It is important to recogn ize that

soi l l i fe populat ions can be increased. They

can be increased by chang ing soil condi -

tions that favor mult ipl ication and soi l s can

be inoculated with n e w or additional popu-

lations.

Here are s o m e soil condi t ions

that lead to increased numbers

and variety of soil l ife:

1. Soil Oxygen - d issolved o x y g e n at 2 + ppm

2. Soil Calc ium Leve l s - base saturation o f

ca lc ium at 75 to 8 0 percent; water-soluble

ca lc ium levels o f 4 0 0 pounds and more per

acre; c a l c i u m - m a g n e s i u m ratios o f 7:1 cal-

culated from the base saturation.

3. Soi l pH - 6 . 4 to 6 .8 A sl ightly acid con-

dition is desired for microbes to cause opti-

m u m nutrient e x c h a n g e to occur.

4. Soil Temperature - A b o v e 50° F. - Ideal

is 70° to 75°.

5. Soi l Moisture - 5 0 to 80% of field

Capacity

6. Carbon - c r o p re s idues and f o o d s

resources must be in contact wi th soi l .

So i l s with organic matter above 2% are

desirable.

7. Nitrogen

8. Phosphorus, potass ium, sulfur and other

minerals w h i c h are "clean" and uncontam-

inated. Certain heavy metals (chromium,

cadmium, nickel , etc . ) and a luminum are

s i m p o s i u i n i n t e r n a c i o n a l 199G

detrimental to microbial populat ions .

9. Supplement ing micro e l ements which

are s ignif icantly def ic ient , according to soil

analysis . Can include: copper, zinc, man-

ganese , boron, iron, and molybdate .

Let us take a c loser look at how

microbial l i fe in f luences soil quality. A s

organic matter returned to the soil is digest-

ed by microbes , the resulting cel lular mate-

rial is m i x e d with the l iving and dead bod-

ies o f bacteria, fungi , ac t inomycetes and

other microscop ic forms of l ife, together

with certain excretory material produced

during their l i fe c y c l e s to form dynamic ,

ever-changing humus . H u m u s is the mayor

storehouse o f plant nutrients in the soil . It

is literally the "fat o f the land."

Soi l microorganisms are involved

in many benef ic ia l activities in the soil .

T h e s e are:

1. decompos i t i on o f crop residues

2. mineralization o f soil organic matter

3. synthes is o f soi l organic matter

4. nitrification and fixation of nitrogen

5. immobi l i zat ion o f mineral nutrients and

formation o f organic substances w h i c h

may be both st imulative and toxic to plant

growth, depend ing upon the concentration

6. building of more stable soil structure by

binding particles o f soil together, which in

turn permits better water penetration and

retention.

Every pract ice or m a n a g e m e n t

sys tem inf luences microbial activity which

in turn in f luences the decompos i t i on of

plant residues, the availability of nutrients

and the soi l structure. T h e s e all in f luence

crop growth, and the growth o f crops deter-

m i n e s the so i l cover and the ult imate

organic matter and humus. This in f luences

the balance b e t w e e n the various types of

m i c r o o r g a n i s m s w h o s e act ions play the

major role in carbon, nitrogen and mineral

c y c l e s , and thus govern the fertility o f the

soi l .

E a c h spoonfu l o f m e l l o w soi l con-

tains bi l l ions o f l iv ing microscop ic organ-

i sms . m u l t i p l y this by the n u m b e r o f

s p o o n f u l s o f soi l in an acre and y o u have

f igures that are astronomical . This seeth ing

m a s s o f microorgan i sms const i tutes a crop

o f three to five tons per acre- foot o f soil

that the farmer sustains beneath the soi l

surface, in addit ion to the crop that he

g r o w s a b o v e the ground. If the crop o f

microorgan i sms beneath the surface d o e s

not have adequate f o o d and the proper

environment , the crop above ground wil l

suf fer from compet i t ion for nutrient and be

more suscept ib le to disease .

"Microorganisms eat at the first

table. T h e y are in contact wi th a lmost every

particle o f soi l . Plant roots are not. (In o n e

acre o f corn, there may be 2 5 , 0 0 0 m i l e s o f

roots, but they c o m e into contact wi th less

than 1% o f the total soi l surface in the

upper s ix to seven inches o f the soi l pro-

file.) Without m i c r o organic l ife, soi l w o u l d

b e c o m e an inert m a s s incapable o f provid-

ing f o o d , " s ta tes Dr. T. M . M c C a l l a ,

research microb io log i s t at the Univers i ty o f

Nebraska .

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S i m p o s i u m i n t e r n a t i o n a l 1996

F U N C T I O N S GF S P E C I F I C M I C R O B E S

Spec i f ic popula t ions o f soi l l i fe

have d i f f erent f u n c t i o n s . E a c h

c lass is very spec i f i c in what it

d o e s . T h e b a s i c c l a s s e s o f

microbes and s o m e o f the j o b s they d o are:

1. Primary producers. These inc lude carbon- f ix ing m i c r o b e s w h i c h tie

up plant carbons and other e l e m e n t s in

c o m p l e x forms for stable storage, then

re l ease it to the next g e n e r a t i o n o f

microbes .

2. Primary consumers. These live on energy from the primary producers.

This c lass o f organ i sms inc ludes d i sease -

caus ing bacteria and larger troublemakers

like nematodes . However , primary con-

sumers a l so inc lude plant-benef ic ia l organ-

i sms such as fungi and m a n y spec i e s o f rhi-

zob ium, w h i c h are the types o f bacteria

w h i c h fix nitrogen.

Another primary c o n s u m e r w h i c h

h e l p s crops is b e n e f i c i a l s trains o f

P s e u d o m o n a s bacteria. T h e s e l ive on car-

bon energy and exudates from the plant,

and in turn help d e f e n d plant roots f rom

pathogens .

A l s o in the primary c o n s u m e r

group: D e c o m p o s e r bacter ia and fungi

w h i c h f eed on organic matter, l o c k i n g its

e l ements into water-stable forms . Without

these, m u c h o f the carbon in plant res idue

w o u l d o x i d i z e away as carbon d iox ide .

3. Secondary consumers attack and feed on primary consumers . T h e s e are

mos t ly saprophytic (absorbing d i s so lved

organic matter including the d e c a y i n g bod-

ies o f primary c o n s u m e r organisms) . The

interchange b e t w e e n primary and s e c -

ondary consumers re leases up to 7 0 % of

the nitrogen needed during the t ime o f

most rapid plant growth.

S o m e of the main microorganisms

involved in soil l i fe are:

Arthrobacters are the dominant type o f soil bacteria. They break d o w n both

residues and chemicals .

Bacillus b ind soi l particles togeth-

er and enhance the n i trogen-f ix ing ability

of Azotobacter microbes . Bac i l lus are a l so

involved in making inorganic phosphates

souble and thus plant-available.

The B a c i l l u s t y p e s p r o d u c e

growth factors such as hormones w h i c h

stimulate plant growth. They break d o w n

c e l l u l o s e in res idue . O n e b e n e f i c i a l

spec ies , Baci l lus subtil is , has been found

e f fec t ive as a seed treatment against fusari-

u m under wet condit ions , it c o l o n i z e s on

the seed and produces antibiotics.

W h e n c o m b i n e d w i t h o ther

spec i e s which fight fusarium in dry condi -

tions, the combinat ion creates a h ighly

e f fec t ive seed treatment for wet or dry c o n -

di t ions . Pitt ing g o o d m i c r o b e s aga ins t

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s i r npos ium i n t e r n a t i o n a l 1996

destructive o n e s has proven as e f fec t ive as

treating s e e d with toxic chemicals .

Azotobacter are nitrogen f ixers

found on l egumes .

Pseudomonads break d o w n

hydrocarbons and many synthetic pesti-

cides.

Streptomycetes produce m a n y

antibiotics. They e x u d e a c o m p o u n d cal led

g e o s m i n w h i c h is responsible for the smel l

of freshly p l o w e d soil .

B E N E F I T S F R O M S O I L M I C R O L I F E

Ten benef i ts from micro l i f e in

soi l s :

1. Microorganisms split c o m p l e x

carbons in residue into "free" crop nutri-

ents.

2. B i o l i f e releases antibiotics to

kill or inhibit disease microbes . D i s e a s e

protection extends season- long .

3. Converts soil mineral to plant-

avai lable nutrients in f o r m s that resist

leaching.

4. C o l o n i z e s crop root hairs in a

symbiot ic relationship, he lping the plant

absorb nutrients. Microbe populat ions in

the rhizosphere, next to the root, are up to

1 ,000 t imes more abundant than in soil

without roots.

5. F i x e s nitrogen from the atmo-

sphere for plant use.

6. Creates po lysacchar ides , the

sticky, sugar-l ike substances w h i c h build

g o o d soi l crumb structure.

7. R e d u c e s the frequency and total

amount appl ied of irrigation water by cre-

ating condi t ions where the soi l can ho ld

and store water more easi ly.

G e n e r a l l y s p e a k i n g , e a c h 1%

h u m u s in a soi l wil l store about 1 inch o f

water.

8. Eases herbicide and insect ic ide

needs b e c a u s e of gradually receding w e e d

and insect pressure.

If ca lc ium and phosphorus l eve l s

are adequate in a b io log ica l ly d y n a m i c pro-

gram, crops aren't as attractive to insects as

those under nutrient stress.

9 . Improves nutrient and keep ing

quality ("shel f - l i fe") in crops.

Th i s inc ludes greater nutrient den-

sity (higher sugar levels ) , l ower nitrate and

non-protein nitrogen content and l e s s sus-

ceptibi l i ty to toxin-producing m o l d s w h i c h

impact the health of l ives tock and humans .

10. Bui lds soi l tilth, construct ing

granules or soil aggregates w h i c h he lp

plants thrive.

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s impos iu i n i n t e r n a c i o n a l 199G

H U M U S IS S O I L L I F E B L O O D

Wi thout so i l l i f e there w o u l d

b e n o humus . H u m u s has

been d e f i n e d in m a n y terms,

but there probably is n o sin-

g le g o o d def in i t ion o f humus . It has many

facets - l ike a human be ing . S o m e scient ists

have de f ined organic matter and h u m u s has

one in the s a m e thing. T h i s is not true!

H u m u s c o m e s f rom organic mat-

ter as bread c o m e s f r o m wheat . Many

things happen in the process . M a n y types

o f bread can be baked f r o m the same

w h e a t . M a n y t y p e s o f h u m u s can be

f o r m e d f r o m the s a m e t o m a t o plant.

H u m u s is produced by the impact o f all soil

l i fe and is built f rom a variety of ingredi-

ents. T h e better the quality and variety o f

organic matter, the better the humus . There

are different states o f organic matter. It is

not ca l l ed h u m u s w h i l e it is still b e i n g bro-

ken d o w n .

T h e i n f l u e n c e of h u m u s on soil

fertility is e n o r m o u s . B e c a u s e the humus

fraction o f the soi l is s o important and mul-

t i face ted . H . H . k o e f p and others have

descr ibed it as hav ing t w o aspects . O n e

aspect they call effective humus; the other

they call stable humus . The in f luence o f

humus on soil fertil ity is s u m m a r i z e d as

f o l l o w s ;

H u m u s is f o r m e d w h e n microbes

take organic matter and convert it to longer

and longer carbon chains . T h i s is d o n e only

under ground by m i c r o b e s that are very

immobi l e . Microbes need carbon sources

and nitrogen sources.

Phase o n e of humus format ion

occurs w h e n numerous spec ie s of microor-

gan i sms break d o w n protein f rom dead

organic matter into peptones , a m i n o acids ,

amines , ammonia , nitrite and nitrate.

Mineral izat ion takes p lace s o that

from the original c o m p l e x , nothing is left

but the s implest c o m p o u n d s o f the e le-

ments . If the process w e n t on indefinitely,

only mineral matter plus C O 2 , H2O, N 2

N O 3 , SO4, and O 2 w o u l d remain .

However , it does not cont inue indefinitely.

Phase T w o o f humus formation

occurs w h e n other organisms take over.

T h e s e stabilize the breakdown and build up

again, reversing the process . From s imple

chemica l structures and pure e lements , for

instance carbon, o x y g e n and nitrogen, they

p r o d u c e sugars , carbohydrates , a m i n o

acids and subsequently proteins and pep-

tide chains.

Organic matter or crop residue

can start out with a carbon nitrogen ratio o f

100:1 or 25:1 and still end up as humus

very near a C : N ratio o f 12:1. A s carbona-

c e o u s organic matter is c o n s u m e d ,

microorganisms cont inue to grow by con-

suming their predecessors .

E x c e s s nitrogen applied to the soil

wi l l require the consumpt ion o f carbon or

humus from the soi l .

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s i m p o s i u i n i n t e r n a c i o n a l 199G

Part o f the c o m -

p l e x soi l l i f e

i n c 1 u ' d e s

e n z y m e s . Plant

roots excrete organic acids

and e n z y m e s , w h i c h in

turn favor microorganisms ,

which in turn release more

organic a c i d s and

e n z y m e s , In a b io logica l ly

dynamic soi l there is a con-

tinuous process o f g ive and

take, release and absorp-

tion, availability and taking

into storage.

T h e plant root rhi-

zosphere is the site of the

so i l /p lant interact ion. It

c o n t a i n s m a n y more

microorganisms and more

concentrat ion o f nutrient

ions than the surrounding

soi l .

A l l b i o c h e m i c a l

action is dependent on or

related to the presence of

e n z y m e s .

T h e variety of liv-

ing organisms wi l l deter-

m i n e the e n z y m e s ' pres-

e n c e and the intensity of

b io logical processes .

• n i a m i i ! i m i i ' m n i i i i ! i ; i i i i i i [ ' i B i i n < l B

What are the impl icat ions for our m a n a g e m e n t

s y s t e m s and ferti l ization practices w h e n w e

b a s e our a p p r o a c h u p o n a B i o l o g i c a l l y

D y n a m i c M o d e l o f Soi l Ferti l i ty?

There are several cons iderat ions that should be

made and s o m e bas ic c h a n g e s i m p l e m e n t e d if w e are to be

success fu l over the longer term. Let ' s look at these from the

perspect ive o f what not to do . We want to stop us ing prod-

ucts or procedures w h i c h harm soil b io log ica l l i fe . A n d

then, w e want to beg in us ing procedures and products

which enhance and build up a v igorous and diverse soi l

microbial l i fe . S i m p l y stated, s top d o i n g s o m e things and

start do ing others.

Here are s o m e things to "not do" or avoid:

1. E l iminate or sharply reduce u s e of l eachable or

high-salt fertilizers. This inc ludes muriate o f potash (potas-

s ium chloride) w h i c h is very aggress ive ca l c ium extraction

agent. There is substantial data s h o w i n g that l ess than 20%

of the potass ium in KCI b e c o m e s avai lable to plants in the

year its applied. M u c h o f the potass ium chlor ide in con-

ventional fertil izer programs is splitting nutrients, particu-

larly ca lc ium from the c lay and organic c o m p l e x .

The soi l d o e s not need the high l eve l s o f chloride

w h i c h c o m e s f rom KCI and chlor ides m a y c o m b i n e wi th

nitrogen to release chlorine gas , harming those microor-

ganisms w h i c h cannot tolerate it, e spec ia l ly benef ic ia l

fungi which l ive in the rhizosphere. Research at the

University of G e o r g i a and e l s e w h e r e has s h o w n the harm-

ful e f fec t s o f chloride salts.^

2. El iminate or sharply reduce a m m o n i u m forms

of nitrogen fertil izers, particularly anhydrous ammonia . It

has a harmful e f f ec t o n ce l lu lose -d iges t ing bacteria and

l l f i

s imp osíum i n t e r n a c i o n a l 1936

also d i s so lves certain h ú m a t e c o m p o n e n t s .

H i g h rate over l o n g per iods o f t ime cause

soi l to get m u c h harder. There ' s a "cement-

ing" effect . A n h y d r o u s a m m o n i a raises the

p H very h igh at the site o f inject ion.

Typical soil pH leaps to 8 to 10 at the site

shortly after its appl ied . Later in the sea-

son, this s a m e soi l usual ly drops l o w e r in

pH than the surrounding area as free calci-

um is depleted.

3. A v o i d t i l l ing w e t soi l . T h e c o m -

paction that results f rom t i l l ing soi l w h e n it

is we t can c a u s e harm to a fertil ity man-

agement program that wi l l last for years.

4. B e w a r e o f mirac le products. N o

o n e can d o all your ferti l ity m a n a g e m e n t

for you, or substitute for teaching yourse l f

the basic principles o f soi l fertility, fit any

product into a c o m p r e h e n s i v e plan and

experiment on a smal l s ca le before you

j u m p too quickly into a n e w program.

5. W h e r e poss ib le , reduce rates

and/or usage o f in sec t i c ides and herbicides.

6. E l iminate use o f fumigants to

control d i s ease -caus ing pathogens . A note

o f caution: do not convert the entire land

area to this practice in a short period of

t ime. A gradual convers ion wi l l have a

higher succes s rate than a sudden one .

7. D o not use e x c e s s i v e nitrogen

rates. Monitor total nitrogen rates c lose ly ,

s ince h igh rates can negate the effort to

build up the so i l ' s h u m u s content and car-

bon levels .

Here are some things to start doing:

1. Institute a residue m a n a g e m e n t

program. U s e t e c h n i q u e s w h i c h m i x

residues from the just harvested crop into

the shallow, aerobic z o n e of soi ls . This trig-

gers the breakdown cyc l e , so nutrients are

mineral ized in t ime to f e e d next year's crop

instead o f compet ing for nutrients during

the growing season.

A combinat ion o f high quality liq-

uid calc ium with s o m e nitrogen, a carbon

source, sulfur and a s eaweed-based active

biological product wil l narrow the ratio o f

nitrogen to carbon and speed up d e c o m p o -

sition.

2. U s e green manure crops. C o v e r

crops improve tilth and add organic matter

s o that humus leve l s m a y be built. With

excel lent fertility, h igh crop y ie lds and

rapid decompos i t i on o f green manures ,

tons of organic matter can be added soi ls .

3. Soil microbial populat ions can

be altered. Spec i e s w h i c h presently exist in

the soil can be s t imulated o reproduce more

rapidly. A l s o the soi l can be inoculated

with new or additional populations.

4. Make ca l c ium the number one

priority in nutrient management . Ca lc ium

is truly the "King o f Nutrients" and g iv ing

primary attention to it wi l l repay large div-

idends.

5. R e c o g n i z e the d i f f e r e n c e

between pH and adequate ca lc ium. Hav ing

pH readings in the so -ca l l ed "opt imum"

1 7

s i m p o s i u i n i n t e r n a c i o n a l 199G

range does not necessarily

mean that there is enough

ca l c ium on an avai lable

nutrient basis. Other ele-

m e n t s directly a f f ec t pH.

6. Wherever pos-

sible, use highly pure fer-

til izers w h i c h have very

low levels of contaminants

and low salt indexes.

7. Manage irriga-

tion practices c lose ly with

the objective o f reducing

the total amount of water

applied in a g iven cropping

season. Frequency of

application also should be

watched. U s i n g less water

wi l l result in an overall

higher level o f d issolved

oxygen in the soil and less

contamination of the soil

by sodium salts.

•

1. Siegfried Lubke of Germany has for more than 30 years researched soil life and its relationship to humus. 2. Pro Farmer News, Cedar Falls, la., May, 1996 3. Ohio Farmer magazine, July, 1996. 4. Presentation made at Field Day sponsored by Soil Conservation Service, USDA, and Cooperative Extension Service, The Ohio State University, August, 1995. 5. Leopold Center for Sustainable Agriculture, Iowa State University, Newsletter, August, 1995. 6. "Soil Plant Pathogens: Management of Disease with Macro-and Micro elements" (Edited by Arthur W. Engelhard) Published by APS Press, American Phytopathological Society, St. Paul, Minn. In this compilation of research, there are many references to the role of calcium in the reduction of several diseases. 7. Public forum, Ranga Velagaleti, Battelle-Kettering Laboratories, Yellow Springs, Ohio; public forum, Fritz Schmitthehner, Ohio Agricultural Research and Development Center, Wooster, Ohio; Progressive Farmer, February, 1983, Myron Parker, Powell Gaines and Gary Gascho, University of Georgia.

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