Written by Jonathan Eisenthal
On a sunny day early in the growing season, before the corn or soybean crop has had time to spread a canopy, the surface of the bare soil around the plants can reach temperatures upwards of 120 degrees.
“It basically cooks the biology right out of the soil,” said USDA Agriculture Research Service (ARS) plant physiologist and conservation ag advocate Jerry Hatfield. “But it doesn’t have to be that way. Reducing tillage intensity and leaving residue or using cover crops are solutions that bring the biology back to that soil.”
And these are solutions that real farmers are succeeding with across the farm belt, Hatfield said.
“When I talk about this, my goal is to help farmers see how this can work in their operation,” said Hatfield, who was the keynote speaker at December’s Conservation Tillage Conference, held in Willmar, with almost two hundred farmers in attendance.
According to Hatfield, cover crops or residue work as a protective coat to the soil that prevent temperature extremes and mute the energy of falling raindrops. On bare soil, the repetitive blows of raindrops loosen and carry away precious topsoil. Bare soil is also prone to wind erosion.
Undisturbed soil offers a stable home for microbes and beneficial animals like earthworms. This in turn helps the soil develop structure, which tillage often obliterates. Aggregate soil structure creates a thriving soil biology that allows the soil to act as a sponge and make the most of rainfall events. Soil that has been intensely cultivated loses structure and becomes crusty and impervious.
“You may get a two-inch rain, but the water begins to pool and run-off, and so a two-inch rain effectively becomes only a one-inch rain, in terms of the moisture benefit to your soil,” said Hatfield, who currently directs the ARS National Laboratory for Agriculture and the Environment in Ames, Iowa.
He admits it may be counterintuitive that cultivation can be harmful to organic matter levels in the soil, because after all, plowing it under is delivering a huge amount of decaying plant matter into the topsoil. The action, however, is also exposing valuable roots to the open air.
“You expose roots to air, they oxidize. By reducing tillage you can keep the carbon that feeds your soil biology, instead of giving it away to the atmosphere,” said Hatfield.
For farmers who are thinking of looking into reduced tillage, cover crops and other conservation measures, Hatfield recommends attending one of the many conservation ag events held throughout Minnesota and beyond to speak with their peers about what is working.
“Farmers want to share what they have done, what has worked for them and what hasn’t, and to learn from fellow practitioners,” said Hatfield.