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Interested in trying a cover crop? Consider planting one after soybeans

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"When we rotate cereals and legumes, we increase the yield of both crops," Trenton Roberts said. "Before a soybean crop, we want to try to plant a cover crop that has more cereals and vice versa."
Soybean is a great crop to plant a cover crop after, especially for those just getting started in cover crops.

For those new to cover crops, try planting one after soybeans.

Soybeans are one of the best cash crops to plant a cover crop before, especially for those just getting started, according to Trenton Roberts, associate professor of soil fertility/soil testing for the University of Arkansas System Division of Agriculture.

Soybeans and cover crops

"If you haven't done much with cover crops before, it can be a struggle to figure out what works for your production system. You need to work out all the kinks as you would with a cash crop," Roberts said. "Also, when planting a cover crop, implementing no-till into your production at the same time is a must to get the full benefits."

To get the benefits from a cover crop, be prepared to go reduced tillage, or to get all the benefits, go no-till.

"Looking at our cash crops, the nice thing about soybeans is we plant them at a high seeding rate," he said. "We may have a seeding rate of 150,000 plants per acre, but research has shown that we can still maximize yield with a plant stand of 100,000 seeds per acre if it's a relatively uniform plant stand.

"Soybeans are the most forgiving crop rotation when using a cover crop, and it goes back to that final plant stand. When we plant into the cover crops, we have residue and moisture as other factors we don't typically have in a stale seedbed or a freshly tilled situation like most of our crops are planted into."

If planting 150,000 seeds per acre and if there is a good, uniform plant stand above 100,000, it is possible to still produce maximum yield.

"There may be some issues with emergence and stand following cover crops, but soybeans allow us to deal with those establishment issues and still produce maximum yield," Roberts said.

"There will be times, especially when furrow irrigating or using flood irrigation, where some tillage may be necessary to ensure that the irrigation is flowing the way we want it to. However, your mindset should be to keep whatever beds or irrigation you start with for as long as possible. Some people pull beds and, even as those beds flatten out and slowly disappear, they still stick with it because they know tillage will set them back a lot of years."

However, working around the lack of plant beds, some tillage, such as using a furrow runner to make a small depression for the water to flow, can be useful. Making such adaptations is better in the long run than going back and repulling beds.

Identify your goals

"We need goal-oriented cover crops," Roberts said. "What is your reason for planting a cover crop? Are you trying to increase soil health, increase water infiltration, or suppress weeds? There are many different benefits we can get from cover crops, so identify the goals you want to achieve with cover crops and look for one that might help you achieve those goals, keeping your cash crop in mind."

For example, if your cash crop is soybeans and you want weed suppression as well as increased soil health and organic matter, you would want a high biomass, low input cover crop. Those are typically going to be winter cereals like cereal rye, black-seeded oats, triticale, and barley.

"It also comes down to which cover crop you can source the cheapest and which one will grow the best in your production setting," he said. "Keep in mind, cover crops rarely increase yield in an irrigated crop production. Typically, we see huge yield increases from cover crops in a rain-fed or dryland system. However, with an irrigated system, you shouldn't expect to increase yields, but instead, you should expect to increase efficiency."

Reducing input costs

Cover crops in an irrigated system allow for reduced input costs, which leads to higher profitability.

"Since cover crops and no-till go hand-in-hand, the money saved from not doing tillage more than pays for the cover crop, and sometimes even puts money back in your pocket," Roberts said.

After a few years of building the soil's health and organic matter back up, the need for irrigation is decreased, and the plants can take better advantage of rainwater.

"We become more efficient with our irrigation, which saves us money on pumping costs," he said. "Over time, we increase the efficiency in an irrigated system, so we don't necessarily increase yields. We do, however, make more money by maintaining our yields with lower input costs."

Cover crops for row crops

Different cover crops work well depending on the row crop in question.

"I always try to encourage people to remember to rotate cereals and legumes like in a cash crop rotation," Roberts said. "When we rotate cereals and legumes, we increase the yield of both crops. Before a soybean crop, we want to try to plant a cover crop that has more cereals and vice versa. If we're planting a cereal cash crop like corn, rice, or grain sorghum, a broadleaf or legume cover crop would work best. This helps in breaking up the pest cycles."

Winter legumes like Austrian winter peas, hairy vetch, and clover provide a lot of nitrogen before a cereal cash crop. Whereas with soybeans, the goal is to have more biomass, weed suppression, water retention, etc.

"Cotton falls into a different category," he said. "It's a broadleaf, not a cereal, but it's also not a legume like soybean. With cotton, it comes down to what your goals are. If you want extra nitrogen, plant a legume, or for weed suppression, plant a cereal."

For rice, Austrian winter pea and hairy vetch tend to do the best in saturated soil conditions. Peanuts, on the other hand, can be treated like soybeans by planting a cover crop such as cereal rye, triticale, or barley.

"There are a lot of benefits that can be achieved with cover crops, but it's something that you want to ease into," Roberts said. "If you are just starting, experiment on a few acres to see what works for you. Also, we encourage people to start with something easy, like cereal rye, because it's hard to mess it up. Plus, it's a cheap cover crop. Figure out what works for your operation and your rotations, and then build from there."

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