Invest in cover crops for your farm

OKABENA, Minn. — Cover crops are a tool, an opportunity and beneficial, according to several experts who spoke at a Nov. 13 field day. Regardless of motivating factor — unless producers are looking for a silver bullet — they're worth trying, said experienced cover crop farmers.

Thanks to January-like cold and a dusting of snow on the ground, more than 100 farmers and other agriculture stakeholders turned out at the Okabena American Legion to learn about cover crops in corn and soybean rotations at the University of Minnesota Extension-organized field day.

A soil-building tool

"Our soil is naked, hungry, thirsty and running a fever," said Ray Archuleta, a soil health spokesperson for the U.S. Department of Agriculture's Natural Resources Conservation Service, referring to conventionally-tilled one- and two-crop rotations.

The root of planting cover crops is improving soil health. The best possible scenario for a field would be to be growing a living root year-round, Archuleta said. Such a system would copy what happens in nature.

Tillage breaks down soil structure, and cover crops directly seeded into corn and soybeans can eliminate the need for full-scale tillage. Although a tiller may not be running in the field, nature's tillers — earthworms, microbes and other organisms — are doing tillage work for producers. Through the course of their work, microbes and plants make nutrients such as phosphorous and zinc available in the soil, key to solid commodity crop growth and fewer inputs in the spring.

"If you don't make the microbes happy, nobody's happy," Archuleta quipped.

Archuleta encouraged producers to thoughtfully consider cover crops and how they may fit in on their farm, rather than just diving in and hoping for instant results. Cover crop systems will take at least two years (the year planted and the year following to assess crop yield) to even start making a difference, although true improvement can take 10 or more years to truly manifest itself.

"Science alone can't convince you," Archuleta said. "It has to be personal to you."

Over time, cover crops can fix compaction issues in fields, Archuleta said. Cover crops also serve to keep nutrients in place during the spring and fall when they otherwise would be leaking away and help cool soil temperatures.

They also can help suppress weeds. Typically planted into standing corn at V7 or V8 (to not potentially negatively affect yields), cover crops can outcompete weeds that might try to pop up later in the growing season.

An economic opportunity

Cover crops may have important ecological benefits, but Scott Wells, a University of Minnesota Extension agronomist specializing in forages and cropping systems, is researching how to bring their economic value to the table. An ideal cover crop will be one that producers can harvest for an additional revenue stream, according to Wells.

To start, Wells and others with Extension are looking at different crops, from cereal rye to hairy vetch to clover to brassicas such as pennycress, to see which will bring the best combination of shade tolerance, winter hardiness and biomass.

In a trial this year at University of Minnesota research and outreach centers at Waseca and Lamberton, Wells' team planted some cover crop options into standing corn at V9 and V10. They found drill treatments were best when shooting for the most biomass but will have to reassess in the spring to see what amounts of biomass made it through the winter.

As his team gets some basic cover crop parameters set, Wells is hoping to eventually determine what to plant, when to plant and where to plant.

A benefit

"Microbes are the ecosystem service providers," said Michael Lehman, a research microbiologist with USDA's Agricultural Research Service. "There's no doubt that soil microbes love cover crops."

One teaspoon of soil contains over one billion bacteria in thousands of species, along with millions of fungi, algae, protozoa and (good) nematodes, Lehman said. These microbes aid in decomposition and nutrient cycling. Crop rotation with cover crops and conservation tillage help create a favorable environment for microbes.

Microbes love cover crops because plant roots exude photosynthate, or fixed carbon, into the soil. The carbon fuels the microbes and allows them to help suppress weeds, promote plant growth, fix nitrogen, protect against pathogens, build soil structure and increase nutrient availability and retention, among other functions.

Lehman, too, cautioned producers to enter into cover crop usage with a long view.

"You need 10 years, you need 20 years, if you want the economics to pay out," Lehman said. "Clover can help in the short term. Rye and vetch are better for the long term. Every year we do this, we don't get the same results (because of precipitation changes). Soil aggregation and soil carbon changes show up after years."

In farmers' fields

In Southwestern Minnesota, Extension educator Liz Stahl worked with three farmer-cooperators to assess how cover crops are working on their farms. Jerry Ackermann, Jerry Perkins and Dave Christoffer spoke about their experiences cover cropping.

Ackermann advised producers to start with the end in mind. He's been growing cover crops since 2010. If the spring is wet, he suggests letting cover crops continue to grow, rather than killing them early. Rye, particularly, is a scavenger of nitrogen, Ackermann said, which is helpful for corn coming up. He likes annual ryegrass for its ability to withstand shade. Through the Conservation Stewardship Program, Ackermann will have cover crops on all his acres in 2015.

"I'm still learning and plan to keep learning," Ackermann said.

Perkins says he's an expert at failing, but doesn't seem to be afraid to keep trying. Cover crops go on strip-tilled corn and no-till soybeans on his farm. The CSP provided support, encouragement and technical guidance as he got going with cover crops, Perkins said.

Christoffer came to cover crops after 20 years of ridge tilling without seeing any soil improvement. He's using cereal rye as a cover in fields with compaction issues. He likes oats for getting more phosphorous into the soil.This year, he got rye seeded in early August. He was worried there may be an issue with combining, but there was not.

All three producers have their cover crops aerial seeded. It can be a challenge to convince flyers to broadcast their seed rather than the higher-paying spraying for aphids, but with a good vendor, the job gets done.

Stahl is working to get funding for larger cover crop project funds. Cover crops will become more important as significant rain events continue to pop up, she said. The research she was able to do this year with Ackermann, Perkinds and Christoffer involved strip trials of seeding cover crops into V7 corn. The trials showed little difference in yield compared to areas without covers, although one site saw 12 bushels per acre less in yield than one without a cover crop. Although her producers saved on nitrogen costs, total inputs for the season on cover crop fields outweighed those on fields without cover crops.

Her cautions for producers going forward include that successful cover crop establishment is highly dependent on precipitation, there is potential for cover crops to become weeds (annual ryegrass has developed some chemical resistances), changing a farm's fertility program can be costly and that a whole system approach is vital (Aggressive, full-scale tillage will wipe out any benefits cover crops provide, Stahl said.).

While getting started in cover crops is no small matter, the long-term benefits, particularly in fewer inputs, can be positive for a farm. Strong soils will make for strong plants.