How do I tell if my soil is
healthy?Think aggregate stability, which you
can determine with an in-field slaketest, says Doug Peterson, NRCS soil health
specialist for Missouri and Iowa.
a. Collect a chunk of topsoil (a size that would fit
in your hand) from an area that hasn’t been
tilled, like a fencerow or pasture.
b. Garner a second chunk or spade full of soil from a
consistently tilled field. It should be the same soil
type as the first sample.
c. Find two clear glass jars large enough to hold
the soil chunks.
d. Build a wire mesh that can be hooked at the top
of each jar. This allows soil to be submerged in the
water yet held within the top half of the jar.e. Insert the wire meshes into each jar and fill the
jars with water.
f. Simultaneously submerge the tilled sample in one
jar and the untilled sample in the other.
g. Observe which soil holds together and which
one falls apart. Soil with poor structure will
begin to fall apart.Why isaggregatestabilityimportant?“If we can get the soil
to hold together in
the presence of water,
water will infiltrate.
That tells us we’re
going to have better
aggregate stability,
better biological
activity – which
translates to better
nutrient cycling – and
fewer nutrients will
be lost to leaching,”
explains Doug
Peterson, NRCS soil
health specialist.Why is healthy soil important?
More soil microorganisms exist in a teaspoon
of healthy soil than there are people on the
earth, according to NRCS literature.
“Millions of species and billions of organ-
isms – bacteria, algae, microscopic insects,
earthworms, beetles, ants, mites, fungi, and
more – represent the greatest concentration
of biomass anywhere on the planet,” accord-
ing to NRCS publications. “Microbes, which
make up only 0.5% of the total soil mass, are
the yeasts, algae, protozoa, bacteria, nema-
todes, and fungi that process organic matter
into rich, dark, stable humus in the soil.”
All those creatures need food. The exudates
from plants feed organic material, which pro-
vides food for the rest of the soil community.
Organisms including bacteria, nematodes,
arthropods, insects, and earthworms
simultaneously work together to feed the soil.
Sunlight and precipitation catalyze the whole
system, while tillage – much like a tornado or
hurricane – destroys this community.
It is a complex system to fathom, says Keith
Thompson, an Osage City, Kansas, farmer.
“I don’t really understand, and I don’t
care. It’s like an engine in a car; it starts and
it runs, and it works,” Thompson says. “The
bottom line is, we’re harvesting the sunlight.
The whole biological system goes to pot with
tillage.”How can I improve my soil’s health?
Reducing tillage and covering the soil is
a great start, says Abbey Wick, Extension
soil health specialist at North Dakota State
University. Tillage destroys a soil’s structure
and infrastructure, which can take years to
repair. Stopping tillage gives the soil a chance
to recover and rebuild the community of soil
life that breaks down crop residues to improve
organic matter.
Further protect the soil surface by inter-
spersing cash crops with a variety of cover
crops, adds NRCS’s Doug Peterson. Keep living
roots in the soil all year long and use all four
plant types: cool season, warm season, grass,
and broadleaves, he says.Photography: Gil Gullickson August 2019 | Successful Farming at Agriculture.com 47