Iowa farmers are continuing to implement new conservation practices on thousands of acres to reduce the loss of nutrients to surface waters under the state’s nutrient reduction strategy, which was adopted in 2013.

In 2015, farmers planted cover crops on 472,000 acres, a 35 percent increase from the previous year, according to a new estimate from the Iowa Learning Farms.

The Iowa Nutrient Reduction Strategy indicates that cover crops are one of the most effective practices available at reducing the loss of nutrients. They are also one of the only practices proven to reduce both nitrogen and phosphorus runoff, because they take up nutrients during the fallow time between harvest and planting and also protect the soil surface from erosion.

Forty percent of respondents to a survey by the Iowa Department of Agriculture and Land Stewardship (IDALS) said they used cover crops for the first time last year, while 52 percent said they’ve been using cover crops for fewer than five years. In addition, 77 percent of the more than 800 respondents said they’re planning on using cover crops again.

"Even though they are early in the process, farmers are showing a commitment to trying the practice and expanding acres as they get the hang of it," said Matt Lechtenberg, water quality initiative coordinator at IDALS. "There is a large effort, in partnership with many organizations, to advance cover crop adoption in Iowa. These groups are hosting field days, often led by farmers, to provide local information on the best ways to manage cover crops."

The survey indicated farmers on average planted about 40 more acres of cover crops than for which they received cost-share. On average, farmers seeded 148 total acres to cover crops while receiving cost-share for an average of 107 acres. Motivation to use cover crops included preventing soil erosion (90 percent), building organic matter (69 percent), improve soil health (68 percent), and improve yields/profitability (47 percent).

The most popular types of cover used include winter-hardy grass (77 percent), brassica (turnip, radish, rapeseed) at 18 percent, and non-winter hardy grass (oats, spring wheat) at 11 percent. As far as their approach to cover crops, 34 percent of respondents said they’d start on small amount of acres and add more acres every year, 58 percent said they use cover crops for erosive potential and 26 percent said they use cover crops to supplement livestock feed.

Sixty-one percent of survey respondents said they seed the cover crop post-harvest. Fifty-five percent said they use the drill method, followed by aerial application prior to harvest at 37 percent.

Kort is a freelance writer in Ankeny.