Iowa farmers have made tremendous progress over the years in controlling soil loss and reducing losses of phosphorus from fields, according to leaders of the Iowa Nutrient Research and Education Council (INREC), a unique public-private partnership established to use local ag retail data to measure and demonstrate environmental progress in Iowa agriculture. Those gains in limiting phosphorus loss show that similar gains in reducing nitrogen loss are also achievable, they said.

“I think we are in a great place in Iowa right now,” said Shawn Richmond, INREC’s director of environmental technology. “Farmers are taking on the challenge of improving water quality in a very proactive manner, and our practices and measurement systems are getting better and better.”

Work done by INREC, Iowa State University (ISU) and others has shown that phosphorus losses from Iowa farm fields have declined 22 percent, as compared to the baseline from 1980 through 1996.

Conservation tillage gains

A big reason behind the im­­provements in phosphorous man­­agement was significant gains in no-till and conservation tillage as revealed in the recently released INREC survey, a statistically sound survey of ag retailers and certified crop advisors to assess Iowa farmers’ conservation practices. INREC then uses scientific assessments from ISU to determine how those practices are reducing nutrient loss from farm fields.

“It’s really an unprecedented undertaking to gather information on Iowa agronomy practices on a field-by-field basis,” Richmond said. “This really puts us in a position that we’ve never been in terms of knowledge of what is happening at a field level.”

Ag retailers and crop advisors have been very supportive of INREC as it gathers information on conservation practices, Richmond said. The survey, he noted, uses aggregated information to maintain the confidentiality and security of individual farmer information.

The INREC information will be invaluable as farmers continue to implement the Iowa Nutrient Reduction Strategy, the collaborative research-based plan to conserve the state’s soils and protect water quality, said Rick Robinson, environmental policy advisor for the Iowa Farm Bureau Federation (IFBF). “The INREC data will provide more accurate information to farmers, their advisors and others as we continue to track environmental progress.”

The IFBF is a member of INREC, and Craig Hill, IFBF president, is vice chair of the organization.

The initial INREC survey, which tracked the 2017 crop year, showed that Iowa farmers used no-till on nearly 30 percent of acres being planted to corn and conservation tillage methods on another 54.2 percent. When planting soybeans, farmers used no-till on more than 40 percent of acres and conservation tillage on another 43 percent.

The use of no-till and conservation tillage has been instrumental in helping to reduce soil erosion, Richmond said. And that, in turn, helps keep phosphorus in place in fields. “It made a lot of economic sense for farmers to conserve the soil, and it produced a nice benefit in reducing our phosphorus losses.”

Later this spring, INREC expects to release statistics on progress in limiting nitrogen losses. As it did with phosphorus, INREC will measure adoption levels based on retailer data and then use science assessments to determine nitrogen loss reductions.

Removing weather effects

This method, Richmond said, works to take weather variables out of the equation when measuring progress. “We know that weather has a big impact on nitrogen movement, and it’s important to have the metrics to take out the weather variations to get accurate information.”

He noted that the INREC’s survey of practices in the 2017 crop year found gains in several practices that have been shown by scientific research to reduce nitrogen loss. Some of those were:

• Farmers used inhibitors on more than 70 percent of fields to keep fall-applied nitrogen in place.

• Cover crops were planted on as many as 1.5 million Iowa crop acres in 2017, a figure that was 70 percent more than previous estimates.

• More fields were treated with nitrogen in a spring pre-plant program (42 percent) than were treated with fall anhydrous ammonia (37 percent).

• The average commercial rate for nitrogen applications was 160.4 pounds per acre for a corn-soybean rotation and 196.6 for continuous corn. Both of those rates are consistent with ISU recommendations.

The INREC survey, Richmond said, highlights how Iowa farmers have stepped up to the challenge of improving water quality and reducing soil loss. “I think that they have demonstrated very well that under the flexible and voluntary practices adoption that fits each farm right, we have made great progress, and we will continue to make progress that using that approach.”