IRON RIDGE – “It isn’t just adding fertilizer and water to grow corn,” says Kevin Erb of the UW Extension soils department. “Soil health management systems matter. Biology is more important than chemistry.”

Speaking at the recent Wildcat Creek/Lake Sinnissippi Soil Health event at the Roskopf Farm at Iron Ridge, Erb admitted getting started with cover crops is an investment.

Not counting cost-sharing that is available to farmers getting started with cover crops, the first year of establishing cover crops will be a financial investment. Erb says that farmers will begin to notice some cost savings in year three as soil health begins to build in earnest.

"By year five you will be making money,” Erb said.

Determining the economic impact of planting a cover crop is not as simple as a one-year, cost-and-return analysis, Erb says.

"Ultimately, the decision to plant a cover crop should be viewed as an investment in the long-term resilience of the farm," he said.

Factors from on-farm challenges to the gradual accrual of soil health benefits will influence when cover crops pay off.

"There are times when a return on investment could take longer but more often the return can come earlier," he said. "When it comes to finances, having a cover crop during a drought year will make the field the most profitable."

According to Erb, a cover crop will increase profitability when meets certain on-farm needs, such as dealing with herbicide-resistant weeds, reducing soil compaction, helping with soil moisture management and soil fertility or providing grazing opportunities.

After three to five years of annual use, well-managed cover crops should start to bring about soil health improvements that improve yields and save on input costs.

Soil health improvements may not happen at the same time. For example, earthworm activity and fungi respond within the first year of cover crop use but it can take as long as five years before soil organic matter starts to noticeably improve, depending on how the cover crops are managed and what tillage is used.

Seeing is believing through the use of a soil pit

The workshop on the Roskopf farm featured a soil pit strategicallyplaced by the Roskopf family to illustrate the difference in soil structure in areas where severe compaction occurs and where it does not.

Dave Roskopf, host of the event, said the pit was dug where silage bags had been located in previous years. This year with the family’s feed storage system relocated, the field where the bags had been was tilled and corn silage later harvested. 

The demonstration showed a definite difference in soil structure in the compacted area compared with the end of the pit where there was no compaction.

Jamie Patton, soil specialist with USDA’s Natural Resources and Conservation Service (NRCS) said soil was additionally compacted this year from the heavy pounding rainfall early in the season. This resulted in a surface crust making it difficult for later rains to soak in.

"There is where a cover crop or debris on the surface would help,” she said. “Roots are the best way to penetrate the soil and loosen it. Corn roots in this field that have been harvested for silage formed baby aggregates and the root hairs bring the soil together.”

She explained that the roots help form a fungus that glues the soil aggregates together. Cover crop roots help transfer the living organisms (fungus) to the next crop in spring and the process starts sooner.

She points out that in a typical corn-soybean rotation there would be five months with nothing living to feed the life in the soil. During that time nothing is feeding those organisms.

“Even when the ground is frozen, rye roots are still growing underground,” Patton said.

In third world countries, Patton says the land is left fallow for a year to let the microbes eat the organic matter.

"They need to do this because they do not use fertilizer," she said.

Cover crops also serve to keep the soils cooler in the heat of the summer. When soil gets about 86 degrees corn roots shut down, Patton says.

“If you plant your corn a little later there is not enough canopy when it gets really hot.  A canopy or a cover crop helps to keep the sun from baking the soil and it stays cool a little longer,” she said.

It was one of four on-farm soil-health workshops hosted by UW-Madison Division of Extension.  Others included the Lower Apple/Horse Creek watershed (Star Prairie); ManCal/Spring Creek watershed, Brillion; and Fisher Creek watershed, Sheboygan. 

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