April 21, 2017
For Tim Smith, farming is about more than just producing corn and soybeans on his Wright County fields. Since he began farming in the late 1970s, he has searched for better ways to limit erosion and save soil. Embracing new technologies, the north-central Iowa farmer is using strip tillage, precision nitrogen application, cover crops, buffer strips, a bioreactor and other practices to reduce loss of nutrients, improve downstream water quality and build soil health.
“I’ve always had a strong conservation ethic,” he says. “My dad was one of the first farmers around here to stop moldboard plowing, and I’ve just carried that on. We need to remember we are farming for the long-term and should do all we can to improve and protect the land and water.”
Smith’s 800-acre farming operation east of Eagle Grove includes land that’s been in the family since the 1800s. He takes a scientific approach to adding conservation practices that fit best on his farm. Speaking at field days and meetings, he shares what he’s learned from using many of the Iowa Nutrient Reduction Strategy practices and soil health practices since 2011, when he first began working with the Mississippi River Basin Initiative, a three-year USDA Natural Resources Conservation Service program.
Improving, protecting soil
In 2014, Smith joined the Soil Health Partnership, a National Corn Growers Association initiative, and began a five-year cover crop demonstration project. It has allowed him to expand his cover crop species field trials to include oats, hairy vetch and radishes, as well as cereal rye. Working with 65 farmers in nine Midwest states, SHP will test, measure and identify practices that improve soil health and benefit farmers’ operations. In 2017, SHP is expanding to 100 farmers.
“I think cover crops are the next big step in improving water quality and reducing soil loss,” says Smith. “Research shows we need something growing on the ground in the early spring, when we often get some of our biggest rains. Cover crops provide that soil protection, and help build soil health. They also scavenge nitrates and can help suppress weeds.”
So far on his farm, corn and soybean yields are comparable when fields are planted with a cover crop in the fall and protect the ground over winter compared to fields not planted with a cover. Smith is confident the cover crops are providing long-term agronomic benefits, too, by improving soil health. He adds, “The soil texture is better, which helps promote root growth and allows for better infiltration of water. There are more earthworms. Cover crops also help increase microbe activity in soil, which is important for crop growth.”
Cover crops, water quality
Can cover crops reduce nitrate loss? A five-year Iowa State University study showed a 35% drop in the amount of nitrate delivered out of a tile drainage system when cover crops were planted. Some studies have seen a 50% to 60% drop depending on the amount of cover crop growth in the fall, which depends on the weather and when the cover crop is planted. Some of the biggest nitrate reductions are in fields where covers are interseeded into the cash crop.
An Iowa Learning Farms estimate showed Iowa farmers planted 623,700 total acres of cover crops in 2016, a 32% increase compared to 2015. In 2009, just 10,000 acres of cover crops were planted in Iowa. However, the Iowa Nutrient Reduction Strategy says 12.6 million acres of covers are needed. “Statewide, we need to expand conservation and water quality practices like cover crops,” notes Smith. “It’s a long-term process, but the benefits will add up.”
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