New tillage guide says less is more

Written by Jonathan Eisenthal

The new “Upper Midwest Tillage Guide” provides Minnesota and North Dakota farmers with a resource for considering the right amount of tillage for their operation and which implements will help the farmer achieve new tillage goals.

The guide looks at the history of tillage before going into the benefits of reduced tillage and how to employ these strategies. Its authors are Jodi DeJong-Hughes, a regional educator with University of Minnesota Extension Service, and Aaron Daigh, an assistant professor in soil science at North Dakota State University (NDSU).

“I took the data from the 13 years that I’ve worked on tillage, along with NDSU data, and what I found is that you don’t need more tillage,” said DeJong-Hughes. “You can reduce tillage and get the same yields.”

DeJong-Hughes noted that the research cited in the tillage guide is from Minnesota and was all done on-farm with commercial-scale equipment.

One of the main misconceptions tillage experts like DeJong-Hughes are battling is a widely held notion that the more mixed the soil, and the deeper the farmer has been able to create uniform soil conditions through tillage, the better.

“The plant doesn’t want ‘uniform,’” said DeJong-Hughes. Tillage disrupts microbes and organic matter that are essential to building the kind of soil structure that plants do want. These desires include lots of macro- and micro-pores to hold water and nutrients, as well as room for the roots to grow without unduly taxing the energy resources of the plant.

One challenge faced by many farmers is the development of a compaction layer in the soil, and the necessity to break through that in order to allow crop plants to grow well. Tillage seems like an obvious answer to compaction. But DeJong-Hughes urged a cautious approach to tillage.

“When you are looking at a certain situation, you have to ask yourself, really, is it a plow that would be the best, or would a twisted shank every thirty inches, just to help do a little mixing solve the problem?” DeJong-Hughes advised. “You can’t undo tillage. But you can do more if you need it. It’s best to err on the side of being conservative.”

An economic analysis included in the guide demonstrates the significant savings from reducing tillage intensity. For example, a two-year rotation using disk-ripping and chisel-plowing costs $48.70 per acre, compared to $39.40/acre for vertical till, and $29.20/acre for strip till.  The study included the cost of the tractor, fuel, labor, depreciation on new implements, parts and repair.

In side-by-side comparisons, DeJong-Hughes said strip till and vertical till produced statistically identical yields with rotations of chisel plow/vertical till, or disk-ripping/chisel plowing.

Still, DeJong-Hughes understands why many farmers resist making a change to tillage, even if the research points to the economic benefits.

“It’s hard to change, to go against tradition, to go against your dad or your dad’s dad,” said DeJong-Hughes. “But farmers have changed their herbicides. They’ve changed their hybrids. They’ve changed their tractors. But they don’t change their tillage—why not? Why not look at different tillage systems. It’s just another area where a farmer can update his operation.”

Research cited in the tillage guide was funded by the Minnesota Corn Growers Association as part of its efforts to make the state’s growers the most sustainable and environmentally responsible in the nation.

You can read the Upper Midwest Tillage Guide here.

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