Depressed corn and soybean prices aren’t deterring Iowa farmers from planting cover crops this fall, says Sarah Carlson, Midwest cover crop director for Practical Farmers of Iowa (PFI).
"I really was nervous when corn and soybean prices dipped that we were going to lose some enthusiasm," says Carlson. "We haven’t seen a decrease in interest. Our phone is still ringing like normal."
Cover crop acreage in Iowa has boomed during the last seven years, from around 10,000 acres in 2009 to more than 500,000 acres last year, as farmers learn how they can help reduce nitrate and phosphorus losses to meet Iowa’s water quality goals. Research shows cover crops can reduce nitrate losses from farmland by 30 to 40 percent and reduce phosphorus losses by around 30 percent.
Multiple on-farm trials show farmers who planted cover crops "had less nitrates coming out of their tiles all year long than the farmers with no cover crops," Carlson says.
Farmer-to-farmer learning has been a key element in cover crop acreage gains across the state, she says. Early adopters have shown how to manage cover crops in a way that not only doesn’t hurt corn and soybeans yields, but provides other benefits like weed suppression in addition to slowing erosion and building soil health.
Farmers are also flocking to field days to learn more about cover crop seeding, termination and everything in between. As a result, cover crops are moving from a curiosity into the mainstream among farmers, she says.
"The comment that I get on the phone is, ‘I watched my neighbor do this for two or three years, and now I’m ready to learn more,’ " Carlson says. "They’re starting to see that their neighbors have not failed, and so now they want to get started. That is the middle adopter, and that’s the majority of Iowa farmers."
PFI studies show that corn yields were equivalent regardless of cover crop treatment in on-farm research trials from 2011 to 2015, reaching near or above 200 bushels per acre the past two years. Yield reductions in prior years were attributed to insufficient cover crop termination or improper planter settings.
For soybeans, PFI’s research documented yield increases in nearly one-third of on-farm trials. Cover crops also help suppress early-season weeds, which can eliminate a herbicide application, Carlson reports. The herbicide savings and potential soybean yield increases, which have ranged from 3 to 8 bushels per acre, can help pay for cover crop seed and application costs.
Finding cash in covers
"Because we’re in tight times, now (farmers) are forced to find the cash in cover crops. We needed to do that anyway," she says. "I think enough farmers have seen that they can break even adding cover crops, that the ones who haven’t quite figured that out are curious enough to keep trying."
Farmers also report benefits that are hard to quantify, like improved soil structure that allows them to get into wet fields a day or two earlier in the spring, Carlson adds. And there are some occasional surprises.
"There are things going on that we’re not measuring," she notes. "This year on a farm we saw sudden death (SDS) reduction where there were cover crops on a soybean field. It was obvious — huge strips of beautiful soybeans where there had been cover crops that spring and the other strips with really poor-yielding soybeans (due to SDS). That’s pretty amazing."
Farmers say ample moisture this fall has provided excellent conditions for cover crop growth. Ben Albright, a Calhoun County Farm Bureau member, said cover crops planted just after he chopped silage in early September are around 6 inches tall.
"Our cover crops look good," he said. "It looks like they survived the frost."
The good fall growing conditions help encourage farmers to keep planting covers, Carlson notes.
No-till farmers have been at the forefront of cover crop adoption, but Carlson says they can also work in conventional tillage systems. Later seedings may not grow much this fall, but will take off next spring when temperatures warm up.
"You still can do this in a tillage system. You just have to tweak your timeline of activity," she says. "It’s OK if they plant by Thanksgiving after doing fall tillage and manure application.
"I’d encourage them to chase the combine. Try 40 acres and see how it works in their system."