Note: The more you
know about soil, the better you can care for it. Beyond stopping
erosion, you can significantly boost the productivity and quality
of soil by improving its health. In this panel discussion, four
soil scientists share what they've learned about the links between
soil life and regenerative farming.
: How can regenerative farming benefit soil health?
SARRANTONIO: By cycling organic matter and
nutrients. Regenerative farming is all about improving soil
health. Face it - farming is not a natural process. It's disruptive
to the soil. When we monocrop, we decrease the diversity of
life forms above and below ground. When we till repeatedly,
we destroy soil structure, promote loss of organic matter and
disrupt nutrient cycles. These practices cripple the soil's
ability to respond to stress and leave it unable to function
the way it should.
Regenerative farming practices try to mimic nature. Diversity
is increased by rotations, by multiple cropping and by creation
of hedgerow habitats. Organic matter is returned to the soil.
Nutrient release from the breakdown of organic materials is
more gradual and should coincide better with changing crop
WEIL: By increasing water infiltration.
When we start a side-by-side comparison of crop rotation with
monocropping, one of the first differences we notice is in
the structure of the soil surface. Especially after continuous
corn or heavy tillage; you see crusting and loss of porosity
in the soil, faster runoff, less infiltration and more erosion.
Surface condition is tremendously important in how much rainfall
your field can hold.
If you're testing infiltration in a field that has recently
come out of alfalfa, it takes only minutes. You may spend
hours waiting in a field that's been in continuous corn.
GOLDSTEIN: By improving soil structure,
which also improves crop root health. These benefits come
hand in hand when farmers use really sustainable practices.
Farmers who expand crop rotations to include perennial forages
and leguminous green manures, and who add livestock, begin
to restore soil health. The contributions of these practices
were learned in the '30s through the '60s, but were then forgotten
with the influx of cheap nitrogen, herbicides and monotonous
Our observations in the Midwest indicate we have soil compaction
and unhealthy roots at epidemic levels as a consequence of
excessive cash-grain production.
DORAN: By showing its we have to balance
the demands that profitable food production makes on soil
today with the improvement of soil and environmental resources
for the future.
The Dust Bowl era in North America provided a vivid example
of this. Early pioneer farmers reaped the benefit of stored
fertility in grassland soils when they used monocropping and
inversion tillage. The loss of soil organic matter, surface
cover and drought resulted in crop failures and in tremendous
erosion losses. The burst of activity with chemicals and monocropping
which started in the '50s is showing up as excessive erosion
and water contamination today.
We must study the way things are structured in nature, but
this is a new approach for many traditional agricultural scientists.
It's alien to much of what we've been trained to do. Our past
marching orders were to produce maximum crop yields to feed
ever-increasing populations. However, in the last two decades,
we are learning to balance the good things about production
with its consequences to the environment.
: What's the most important concept to learn?
WEIL: Soil is not a hydroponic medium.
You can't spoon feed fertility to roots, even if you apply
all the fertilizer a corn crop needs. In a corn-soybean rotation
on most soils, if you put on 15C pounds of N, less than 50
percent is likely to end up in the corn plant. It can be as
little as 10 percent. The N that does reach the plant may
come from last year's fertilizer or from the last decade's.
Adding new fertilizer may cause more N uptake, but even that
is mostly "old" nitrogen that enters the plant because
the nitrogen cycling system kicked into a higher gear.
It's like a biological banking system. The dollars you get
out are not the same dollars that you deposited.
DORAN: Soil is a living, dynamic organism.
It functions most effectively when the physical, chemical
and biological components are in a state of dynamic balance
- a balance between the "living" and the "dead."
Whenever we manage the soil to produce crops, we upset the
natural balance, especially when little plant residue is returned
to the soil surface.
GOLDSTEIN: Soil responds strongly to how
we treat it. As Ray alluded, the old thinking was that soil
is an inert sponge for holding nutrients and water for plants.
Now we know that soil has living and mineral parts, and that
we can build up its strength or run it down.
Teaching about soil fertility in terms of soil chemistry has
had a paralyzing effect on our sense of what "healthy"
soil is. Everything became abstract. To do the soil justice,
we need to put chemistry in the context of living processes.
In reality, the carbon in cornstalks has a different significance
- and less beneficial effect - for soil fertility than the
dynamic weaving activity of carbon in grass roots. Similarly,
the living nitrogen process of legumes has a totally different
effect on soil animals than does mineral nitrogen from a bag
We can learn to recognize a soil's health by its form and
by its living qualities. Certainly, tillage that fluffs up
soil can fool us. But if we make observations on a soil that
has settled well, the amount of soil crumbs between 1/32and
1/3 inch in size can give us a good idea of its structural
quality and its potential for microbial activity and nitrogen
release. The more particles in this range - and the more stable
they are - the better. Abused soils tend toward the extremes
of forming massive clods or powder.
SARRANTONID: Keep your sense of humus! Maintaining
active soil organic matter is the key to keeping almost everything
else healthy in the soil. Cycling active organic matter maintains
soil structure, provides nutrients, helps retain and recycle
added nutrients, and provides habitat plus water-holding capacity.
: So how can farmers best improve soil health?
GOLDSTEIN: Maximize soil builders. Use crops
that will build your soil, such as fine-rooted grasses, deep-rooted
perennial and biennial legumes, and cover crops. Use animal
manure. These resources can he raised on your farm. They stimulate
soil microorganisms, improve nutrient cycling and availability,
and enhance the soil's fertility.
Manage soil depleters.
Be careful how many grain crops you grow - especially sorghum,
corn and wheat - because they destroy soil structure and fertility.
Their repeated use leads to accumulations of soilborne, disease-causing
microorganisms that live partly on cereal straw, partly on
crop roots. Cash-grain farmers can build up their soil structure
by underseeding or overseeding legumes such as sweetclover,
red clover or hairy vetch as green manures. This practice
also makes the soil environment less supportive of disease-causing
Learn from your roots. Dig them up, wash them, study them.
If they aren't white, ask yourself "Why?" Roots
need oxygen to grow. Look at your soil in the middle: of summer
and ask yourself if oxygen can get down into it. If you were
a plant, would you like to root there? The trick to growing
crops with good yields using few or no chemical inputs is
to grow healthy crops with healthy roots. These crop plants
can compete strongly with weeds for moisture and nutrients.
SARRANTONIO: Take full advantage of cover crops.
Continually improve vour system to better use covers to supply
nitrogen, protect soil from wind- or rain erosion, add organic
matter, take up excess nutrients, create a nice crumb structure,
or act as a food source or habitat for the tons of soil organisms
we want to encourage.
||"CORNSTALK CARBON IS LESS BENEFICIAL
THAN CARBON IN GRASS ROOTS." - WALTER GOLDSTEIN
and till as little soil as you can. Ridge tillage involves minimal
soil movement, yet provides for incorporation of organic matter,
greatly cuts down erosion and keeps soil biological activity
at a high level. Permanent ridges make it easier to have controlled-traffic
lanes where you run all your equipment, leaving most of the
field's root zone uncompacted.
Recognize which types of tools cause compaction. ones that lift
topsoil by pressing down on soil below - such as a moldboard
plow or disk - tend to compact. Less prone to create tight layers
are tools, such as a spring-tooth harrow, where tractor or implement
tires support the weight of the engaged topsoil.
DORAN: Use crop rotations to reduce pest
problems and increase biological diversity. Growing the same
crop every year sets the stage for a buildup of plant disease,
weeds and insect populations.
We break these trends by incorporating grass sod or cover
crops in a rotation. These practices protect the soil surface
for more of the year. In the soil, the variety of roots and
residue from covers helps to increase beneficial species of
soil life that compete with weeds and disease organisms.
The diverse mixture of plant materials also creates a more
hostile environment for pests. Rotations help take away the
crop-specific overwintering sites that pathogens and insects
need to survive.
: Why should farmers work for healthier soil?
SARRANTONIO: So we can keep on farming.
Farming without keeping soil health in mind is like painting
over termite holes in the frame of your house. We can kid
ourselves for only so long. Healthy soil should not be considered
a "luxury" that we work toward only after we meet
our immediate economic needs. It is an absolute necessity.
This amazingly thin, fragile layer of material coating less
than half the earth is the key to human existence. Doesn't
it make sense to take care of it?
DORAN: To achieve global environmental balance.
The soil plays a critical role not only in supporting crops,
but also in acting as a living buffer and filter. It completes
the carbon and N cycles on earth and influences the quality
of the air we breathe and water we drink.
Sometimes the imbalance affects farmers directly. In parts
of Nebraska, rural communities have gone to drinking bottled
water because their groundwater has a nitrate level of more
than 30 parts per million of nitrate-nitrogen. (EPA drinking-water
guidelines for infants set a nitrate limit of 10 ppm.) The
30-ppm level amounts to about 81 pounds of nitrogen per acre-foot
Some farmers, who are over-irrigating to maximize yields,
put on 3 acre-feet of water in a season. A lot of the N in
that water will leach. Even in this situation, building healthier
soil can help. It holds more water, so there's less leaching
and less need for irrigation. To maintain a "healthv"
soil, farmers should monitor nitrate in soil and water to
reduce unneeded nitrogen inputs.
WEIL: To improve long-term productivity.
It is possible to improve your soil's health, rather than
have it go downhill over time. Healthy soil is more stable.
That doesn't mean it's neutral or static, but that it has
a complex, dynamic equilibrium that keeps its systems from
crashing. It keeps functioning even under adversity, because
those systems are self-regulating.
GOLDSTEIN: To avoid disaster. Soil health
contributes enormously to longterm yields and crop reliability.
Crops in unhealthy soil are more dependent on chemical inputs,
even though they are unable to use them as efficiently. Conventional
fields that farmers convert "cold turkey" to non-chemical
systems show the results of unhealthy soil and roots: Crops
look poor and weeds look great.
: If you had only 5 minutes to evaluate soil health in a moist,
harvested wheat field in July, what would you do?
WEIL: I'd brush away the residue and take
a close look at the soil surface to see if it was crusted,
which would tell me something about tillage, organic matter
and soil structure. I'd push a probe down about 12 inches
and lift out the soil to feel its texture. if there was plowpan,
I'd feel it as the probe went in.
I'd break the soil cores into depth intervals: the top 2 inches,
then two 5inch sections. I'd measure each with a pocket pH
meter. Often in reduced-tillage situations, pH problems are
concentrated near the surface.
I'd turn over a shovelful of soil. If I didn't see any earthworms
or their holes, I'd be worried. I'd smell the soil for that
rich, earthy scent that comes from the presence o£ actinomycetes
(moldlike microorganisms that help to compost and stabilize
decaying organic matter).
It would be a busy 5 minutes.
DORAN: I'd use a soil auger to probe down
about 4 feet. I'd check depth and color of the topsoil, the
presence of soil insects or earthworms and the filth in various
levels. I'd look at root depth to see the ability of the soil
to support plant growth and to find if anything is inhibiting
root growth. If the soil didn't look biologically active,
I might run a quick test for soil pH and electrical conductivity
using pocket meters.
SARRANTONIO: Ha! Trick question! The whole
idea of soil health is to go beyond the superficial, instant
analyses we thought were adequate in the past — the
old N-P-K mentality. We need to look at all kinds of different
things and how they interact — soil organisms, soil
structure, soil fertility. And that takes more than 5 minutes.
GOLDSTEIN: These all are good. One little
fact should be added. Farmers often pick up some soil and
come to a quick judgment: this soil is dead, burned out; or,
this soil is rich, alive, fertile or has good filth. What
do such common experiences mean? Qualities of soil speak intimately
to us as humans because we feel something of them in ourselves.
We need to appreciate such experiences, and even train our
capacity to have them, because they can be of great practical
: Are resources better used to develop computer-based "expert
systems" in soil health or in sharpening farmer expertise?
DORAN: Regenerative farming will likely use
computer-based "expert systems" to monitor the soil
health in quantitative terms. But the "experts"
in regenerative systems will have to be farmers who are managing
the land. They must have simple tools for assessing soil health
and incentives for improving soil health. What we need is
a stronger partnership between researchers and land managers,
and increased government support for "onfarm" research.
|"ROTATIONS HELP TAKE AWAY THE
CROP-SPECIFIC OVERWINTERING SITES THAT PATHOGENS AND INSECTS
NEED TO SURVIVE." -JOHN DORAN
WEIL: Expert systems can make a pretty graph
for fertilizer recommendations. But we don't even know enough
about soil health to really have experts, let alone expert
systems. A farmer's gut feeling about soil is worth as much
as a computer model.
SARRANTONIO: I don't think computers will
ever be able to substitute for personal experience, a keen
eye or creative mind. Computers can handle lots of information,
but they are incapable of original thinking, and that' what's
needed for regenerative farming.
GOLDSTEIN: Expert systems will be useful
only if they give farmers the right ideas of what to look
for. It takes a human being with training and experience to
properly assess soil health because health is not a tangible
"thing" that any instrument can measure. Just as
valuable as chemical analysis is the knowledge of an attentive
farmer who knows how a soil works and crumbles, and how it
and the crops it grows have responded to good or poor management
over the years.
NEW FARM: What has been your most significant soil-health
WEIL: Take your own soil samples—as
often as you can. Stop long enough to put your hands in the
soil and remember what you feel. Set aside days when that's
going to be your first priority.
SARRANTONIO: Soil really breathes! When we began
to measure the rate of carbon dioxide release from soil, I
was astounded at how it responded almost instantaneously to
changes in tillage, residue or moisture. It really reinforced
the concept that the soil acts as an organism - that it's
alive and needs to be nurtured.
DORAN: Look at the big picture. Be aware
of all the effects of agricultural management on the physical,
chemical and biological components of the soil environment.
We have to adjust practices to seasonal changes in the availability
of nutrients - particularly N - and in the potential loss
of nutrients through erosion, leaching and microbial conversion
GOLDSTEIN: The best soil research tool is
a shovel in the hands of a farmer who knows a field's history.
Farms are living storybooks. They tell us a lot if we pay
attention to the present signs and past management.
A soil records its past, often how much it has been abused.
Look at the soil under grass in fencerows. Compare its topsoil
depth and earthworm holes to that of soil in the fields. Remember
that the life of the soil varies with the seasons. Gain a
sense of that dynamic.
The soil itself will teach us significant things if we pay