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LEVERAGING SOIL BIOLOGY

This article is a tribute to the late Matt Hagny who was show up—but these beneficials can’t prosper in the barren
tragically killed in a rock climbing accident in 2019. Matt was wasteland of a tilled field. However, a winter cover crop
a driving force in the formation of No-till on the Plains and
was extremely influential in no-till adoption in KS, OK, and killed just before cotton emergence (or early postemerge)
NE. This article is condensed from a full length article first really builds the spider and lady beetle population early,
published in No-till on the Plains Leading Edge Magazine in which will typically control thrips, aphids, and bollworms.
2003. As you will see, Matt was far ahead of his time with
this insightful article from 17 years ago. Similar measures keep corn borers at bay—a good supply
The complete article can be found on our website by searching “Leveraging Biology”. of lady beetles will devour most of the eggs and larvae, al-
Think of your fields as ecosystems where nature isn’t easily though it is strictly a “numbers game.” Other insect prob-
confined or excluded and life is quite resilient. Instead of lems can also be avoided with good management. Corn
focusing on wiping out the population of pesky organisms, rootworm can often be handled by proper rotation, which
we should instead be looking to avoid the confrontation, is basically deprivation of a host.
or at getting the suppression some other way. “Brute force” A Jungle Out There
technology generally fails to subdue biology—the technol- What about weeds? They do seem to “disappear” when left
ogy is very costly, plus, the target often evades the control on the soil surface, which is well documented (see Randy
measure and the side-effects are sometimes unanticipated Anderson’s data). Some of this is biology (predation), and
and unpleasant. We need to look for ways to manipulate some is just pure weathering and chemical degradation.
the system to get what we want—to find those places where Leaving the weed seeds on the soil surface maximizes
we can exert small pressures and produce big changes, to these mechanisms. Temperature fluctuations and sunlight
leverage biology in our favor. are strongest on the surface, as well as the most feeding by

Hired Guns ants, beetles, crickets, etc. The greatest amount of biology
One of the most visible ways of leveraging biology is using is almost always in the duff layer on the surface and the
beneficial organisms to control harmful ones—nurture half-inch of soil underneath and the same microbial and
your allies and let them fight your wars for you. Some farm- fungal feeding that degrades stubble also works to destroy
ers purchase and release beneficials in their fields to boost weed seeds. Generally, most of these decay processes are
numbers, but why not just ensure that their numbers are accelerated under crop canopy conditions as the humidity
high from the start? This is what can occur in a well-man- is kept higher.
aged system following soil health principles. Keeping crop Another component of biological control of weeds is com-
residues on the surface holds moisture and creates an envi- petition from your crop. Sunlight and nutrients are limited
ronment suitable for these beneficial organisms, ensuring in supply, not to mention pure physical space to grow so
their population builds early and stays strong. Lady beetles make the crop (or cover crop) as competitive as possible.
and lacewings are often given most of the credit, but spiders Of course, rotations are key to effective biological control,
actually do much of the work when it comes to controlling as crops will be competitive at different times of the year.
damaging insects. Beyond competition for resources, cover crops may even

In cotton, for example, spi- actively suppress weed growth with “chemical warfare”—
ders are very important for
controlling fleahoppers. Es-
tablishing a good beneficial Photo by Keith Berns
population early involves
providing habitat and a food
source for them, by keeping
Photo by Matt Hagny better yet, a growing crop)
residue on the surface (or,

and not spraying insecti-

Double crop cotton? No, this was seeded into a cover cides. Spiders and lady bee-
tles will feed on a wide range
crop of wheat, which was killed while the cotton was
seedling. The evidence is convincing: cover crops of other organisms, and can
ahead of cotton build populations of spiders and
lady beetles, which works wonders for controlling the establish populations long
thrips, fleahoppers, aphids, and bollworms that show before damaging insects ever
up later. Biocontrol for free!

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