But in the past few years, a second planting season has emerged in the fall. That’s because more and more Iowa farmers are planting cover crops.
Using airplanes, modified spraying rigs and conventional planters, Iowa farmers sowed approximately 472,500 acres of cover crops in the fall of 2015. That was an increase of 35 percent compared to 350,000 acres in 2014, and up dramatically from less than 10,000 acres in 2009.
And there are clear indications that the state’s cover crop acreage will continue climbing as the state’s farmers take on the challenge of improving the state’s water quality and reducing soil loss.
During last month’s Iowa State Fair, Iowa Agriculture Secretary Bill Northey announced that his department had received applications covering over 200,000 acres from more than 1,900 different farmers seeking to participate in the program.
More than 900 Iowa farmers had enrolled in the program to access cost-share funds to help them try cover crops for the first time, Northey said. Another 1,000 farmers who had already tried cover crops are accessing a reduced rate of state cost-share to plant them again, he said.
That means farmers will be investing nearly $6 million of their own money, while accessing $3.8 million in state funds through the Iowa water quality initiative, officially called the Iowa Nutrient Reduction Strategy.
Many Iowa farmers are planting cover crops and investing in water quality on their own, without government assistance. A recent poll by Iowa State University (ISU) also showed that farmers have invested as much as $2.2 billion to make those conservation improvements.
Northey said farmers’ interest in cover crops and other conservation practices is very encouraging, especially at a time when sharply lower commodity prices have dramatically reduced farmers’ income.
“Farmers continue to take on the challenge of improving water quality and invest in practices focused on limiting nutrient loss,” Northey said. “Even in a challenging time economically in agriculture, we have a record number of farmers participating and willing to put their own money towards these practices," Northey said.
Cover crops are a key to improve water quality because they have been shown to reduce losses of nitrates and phosphorus that could otherwise end up in surface water, according to research by ISU and others.
Farmers plant cover crops either into maturing fields of corn and soybeans before harvest or immediately after the combines are finished. Then the cover crops — typically rye or a mixture of rye with varieties of turnips or radishes — germinate and grow during the late fall and early spring, after the fall harvest and before the next spring’s planting.
By growing during the off-season for corn and soybeans, cover crops help protect the soil from eroding over the winter and early spring months. Cover crops also scavenge residual nitrogen left in the soil. That’s especially important in the spring, when soils are often warm and wet and are vulnerable to nitrate loss.
Research has shown that a rye cover crop reduced nitrate concentrations by an average 31 percent and that cover crops can also reduce phosphate loss by about 29 percent.
In addition, studies have shown that cover crops can improve soils while providing habitat for birds, wildlife and beneficial insects.
Cover crops don’t work on every farm in Iowa, agronomists caution. That’s especially true in the state’s northern counties, where it’s tough to get cover crop seed planted and germinated before a hard freeze.
Still, cover crops are a promising tool that more Iowa farmers have embraced as they step up to improve water quality.