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
: 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 needs.
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 cash-grain farming.
Our observations in the Midwest indicate we have soil compaction
and unhealthy roots at epidemic levels as a consequence of excessive
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
: 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 or tank.
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
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
WEIL: Compact 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
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 of water.
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
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
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
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 significance.
: 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"
|"ROTATIONS HELP TAKE AWAY THE CROP-SPECIFIC
OVERWINTERING SITES THAT PATHOGENS AND INSECTS NEED TO SURVIVE."
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
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 to gasses.
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
The soil itself will teach us significant things if we pay attention.