WASHINGTON, Sept. 23, 2015 - Corn and soybean farmers in several Midwestern states are using state cost-share programs and the age-old method of trial and error as they start to plant more acres of cover crops.
Cover crops have grown in popularity among farmers in recent years as a way to minimize soil erosion, build organic matter in soil and keep nutrients in the fields – and out of waterways. The key property that makes cover crops so promising for conservation is their roots, which help to keep nitrogen and phosphorous in the soil through the winter when cropland would otherwise be bare and susceptible to erosion and runoff.
Reduced runoff translates to fewer nutrients ending up in waterways where they can feed toxic algal blooms and impair fisheries and wildlife habitat, like in the Lake Erie Basin. Treating nutrient pollution before it affects drinking water supplies is also proving costly for water utilities in Iowa. However, cover crops can be expensive and risky to establish since in some Iowa cornfields they’ve been having negative impacts on yields.
In Iowa, a $3 million project called the Sustainable Soy Program, led by Unilever and Archer Daniels Midland (ADM) the Conservation Technology Information Center and several agricultural industry partners, is helping farmers make the leap by providing up to $25 an acre in cost-share assistance to plant cover crops. Bill Northey, Iowa’s agriculture secretary, told Agri-Pulse he estimates seeding cover would cost producers about $50 per acre without the leg up.Even with the assistance, the average Iowa cost-share participant is taking it slowly, only planting cover on about 100 acres at first, he said. “They’re not doing it on their whole operation – they’re trying it” to see whether the soil health benefits trump the costs, Northey said.
According to Iowa’s most recent agriculture census, there were about 375,000 acres planted in cover in 2012. Matt Lechtenberg, the water quality coordinator for the state ag department, told Agri-Pulse he estimated that had increased by about 200,000 acres in the past three years, largely due to cover crop assistance programs. The state farmed a total of 23.4 million acres of corn and soybeans in 2012.
The benefits of cover crops can be limited, however. For one, there are only so many cover crop species suitable to the Midwest’s shorter and colder growing seasons. Rye and oats have been shown to reduce nitrogen runoff by 31 and 28 percent, respectively, in Iowa cornfields, but other non-leguminous cover species have an even larger impact – an average of 70 percent reduction in runoff – in U.S. states with longer growing seasons.
And while rye cover does not affect soybean yield, a 6 percent reduction has been measured in some corn yields in Iowa, according to officials working on Iowa’s nutrient reduction plan. So if rye cover was used on 60 percent of 21 million non-rotated corn and corn-soybean acres in Iowa, corn production could potentially drop by 77.1 million bushels, assuming a 170-bushel corn yield. The state’s corn crop totaled almost 2.4 billion bushels in 2014.
However, in other states, those yield decreases haven’t been recorded. Chad Watts, a project director and cover crops expert with the Conservation Technology Information Center (CTIC), said farmers might see yield reductions if they aren’t sure how to integrate cover into their operations, but most find that cover delivers “a bang for their buck.”
“It’s as much an art as it is a science,” Watts told Agri-Pulse. “We’re learning so much along the way” about which cover species work best in different soils and climates and what time of the year is best to plant cover. “But it works well, provided you think it through and adapt your system for growing cover crops,” Watts said.
Seeding cover is cheaper to implement than many other conservation practices – even in Iowa. Planting rye cover in the state costs between $39 and $88 per acre, and that’s including the cost of seed, spreading the seed and corn yield impacts. When coupled with inexpensive conservation practices – like changing the rate and timing of manure or fertilizer application – cover crops can be more effective in reducing nutrient runoff than more expensive conservation methods, such as installing edge-of-field water control systems, like wetlands or bioreactors, Watts said.
According to CTIC’s 2015 annual cover crop survey, nearly 60 percent of the 1,200 farmers surveyed across the nation said they had never accepted financial assistance to plant cover. Watts said those farmers likely brought on cover crops years ago in conjunction with other conservation practices and found cover crops to be a cost effective way to control runoff and improve soil health.
“They’ve drunk the Kool Aid, so to speak,” Watts said, and like the flexibility they have to experiment when USDA isn’t involved.
Minnesota farmer Jim Purfeerst, who owns 3,000 acres of corn and soybeans and a cow calf operation in Rice County, Minnesota, think they may have found how to best balance cover crop costs with soil and water quality benefits.
He and Bruce Peterson of Far-Gaze Farms – an 80-year-old, 6,000 acre corn, soybeans, hog and heifer operation in Northfield, Minnesota – have been “interseeding” cover crops with row crops on their land with the help of USDA Natural Resources Conservation Service (NRCS) soil expert Tom Coffman for the past two years.
And while the farmers have successfully grown some varieties of cover crops – namely turnip, radish, cereal rye and annual rye – a short growing season and “herbicide carryover” limit the ways they use cover to accomplish soil conservation.
In Rice County, the growing season ends the first week of October and the harvest is finished in November, “so there’s not a lot of time in the fall to get cover crops seeded,” Coffman said.
If the cover is planted in October, farmers can expect it to germinate and return in the spring, but doing so only allows for “about one month of roots in the soil” before winter comes, which isn’t ideal, Coffman says.
When farmers do a June interseeding of cover crops, they “end up with five months of live roots in the soil, which we feel is a real advantage” in terms of soil health benefits, he said, and it means a more diverse array of crops can be planted.
Peterson and Purfeerst chose cover crops that are shade tolerant and used a spinner spreader or helicopter to disburse the seed. The seed typically germinates quickly in the wet June soil and is able to survive under the soybean and corn canopies through the summer. Once September comes, “the cover picks up more sunlight and takes off,” Coffman said.
Some USDA policies will need to change in order for interseeding to be eligible for cost-share dollars. Currently, NRCS provides funding through the Environmental Quality Incentives Program (EQIP) and the Conservation Stewardship Program (CSP) based on a “practice standard” that stipulates planting cover occurs between April 1 and May 15, or after Aug. 1. But farmers like Purfeerst say they need more time in May. “Our county is bringing a resolution to the state convention this year trying to get those dates switched around, but we can’t interseed cover crops with standing crops” in the meantime and receive NRCS funding, Purfeerst said.
This year, Coffman and Purfeerst have also identified herbicide damage in the cover crops that they’re attributing to Halex, which is used to control waterhemp and ragweed on glyphosate-resistant acres. “We’re thinking the roots (of the cover) are down to a point where they’re starting to pick up some of that Halex,” Coffman said. “The residual herbicide is one of the challenges we’re going to have with cover cropping.” Purfeerst said herbicide carryover wasn’t a problem last year, so he was confident a solution could be found. “We’re not going to quit, we’re just going to learn from what we’re doing this year.”
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