Improving soil health may require more use of cover crops
WORTHINGTON — Farming practices haven’t been kind to the agricultural landscape since farmers first began tilling up the prairie soils of southwest Minnesota more than a century ago.
The common two-crop rotation of corn and soybeans has contributed little organic matter to the soil and even less cover to protect the landscape from the winds that often blow across the region.
Jay Fuhrer, dubbed the Waterway King of North Dakota (he’s a Natural Resources Conservation Service conservationist in Bismarck, N.D.), was in Worthington on Thursday to address soil health and the advantages of beneficial crop rotations, cover crops and livestock grazing on farm fields.
Before a crowd of more than 70 attendees at Minnesota West Community and Technical College, Fuhrer shared how he spent the first half of his career building drainage ditches and designing waterways because North Dakota farmers couldn’t get water into the soil profile. Every time it rained, the water flowed across the landscape. That, combined with wind erosion, meant a lot of nutrient loss on farm fields.
By the 1990s, Fuhrer said a team of conservationists came together as a team and decided their approach had to change.
“We can’t keep going the way we are — it’s non-sustaining,” he said, adding that with the focus placed on conserving a degrading resource base, the team developed ideas to rebuild soil and recreate the pore spaces that once existed.
“The more we tilled, the more we took out pore spaces, the drier it got and the more we tilled,” he explained. “After applying some of the soil health principles, we started to see changes occur.”
Fuhrer presented five principles of soil health during his talk. Those principles include keeping the soil covered, minimizing soil disturbance, maximizing diversity, planting cover crops and integrating livestock on the land.
Keeping the soil covered is the result of planting cover crops, and Fuhrer said he once had a farmer tell him that if you appreciate the soil, you won’t see it. He encouraged farmers to use a combination of high-, low-and mid-carbon residue crops to help build up carbon in the organic matter. Wheat produces a higher level of carbon in the soil than corn stover, and corn stover builds up more carbon than alfalfa, he noted.
Minimizing soil disturbance has been the goal of farmers practicing no-till for years, but Fuhrer said practicing no-till in a corn-soybean rotation leaves no armor on the surface to protect the soil. A common problem in no-till operations is soil compaction. To minimize soil compaction, farmers — in addition to leaving residue on the soil — can also maximize diversity by planting multiple species of cover crops to benefit soil health.
“In no-till, we minimized carbon loss, and with cover crops, we maximize carbon input,” Fuhrer said, adding that the two concepts work well together.
His fifth principle of soil health — livestock integration — focused on the need to reintroduce livestock grazing on the land.
“About 85 percent of nutrients will remain in the field with livestock grazing,” said Fuhrer, adding that a cow will convert nutrients in the residue into a more useable form.
As part of Thursday’s program, Fuhrer and local NRCS District Conservationist Stephanie McLain conducted a slake demonstration to show the difference in reactions when healthy soil and unhealthy soil come in contact with water. The unhealthy soil lacked structure in the aggregate and fell apart, while the healthy soil from a stable ecosystem absorbed the water. In addition, water containing the unhealthy soil had a buildup of scum on top, while the water containing the healthy clod of soil remained mostly clear.
“Can we take this (unhealthy) soil and make it as strong or stronger than (the healthy) soil?” Fuhrer asked attendees. “Absolutely! Plants fix soil.”
Farmers continuing a corn and soybean rotation, with the implementation of no-till, would take a while to show soil structure improvement. Fuhrer said they might reach an equilibrium.
However, if a third crop was introduced to the rotation, such as the higher carbon-producing wheat, soil health will improve at a faster pace. Introducing a cover crop to a three-crop rotation would be even better, and the best option would be to do a three-crop rotation, plant cover crops and add livestock.
“It depends on how much diversity you’re willing to apply,” he told the group.
In Burleigh County, N.D., Fuhrer said it took farmers 12 years to gain 1 percent organic matter.
“When we had degraded soils, we were not very efficient in the water or nutrient cycle,” he said. “In order to gain soil organic matter, you have to have less organic matter leaving than coming in.”