Iowa Bets on Data to Cut Fertilizer Waste and Clean Up Its Rivers

Iowa launches free residual soil testing to help farmers reduce nitrogen costs and cut fertilizer runoff into state waterways

1 May 2026

Iowa has launched a state-backed programme offering free residual nitrogen testing to farmers, in an effort to cut unnecessary fertiliser use and reduce chemical runoff into the state's rivers and water supplies. The three-year Nitrogen Soil Sampling Project, run by the Iowa Department of Agriculture and the Iowa Nutrient Research and Education Council, began on April 13 and is initially open to producers in five counties north of Des Moines.

The timing carries weight. Nitrogen fertiliser prices remain near record highs, profit margins on crops are thin, and modelling by Iowa State University suggests that residual soil nitrogen levels this spring are higher than usual, following a mild winter.

Farmers who apply at standard rates without first testing their soil risk paying for nutrients that are already present, while sending any surplus nitrogen downstream into rivers and municipal water systems. The Des Moines metro area has long contended with elevated nitrogen in its drinking water, a problem driven largely by agricultural runoff. Treating the issue at the farm level, rather than at the water treatment plant, is central to the programme's logic.

Test results feed directly into N-FACT, a digital tool developed by the Iowa Nitrogen Initiative that generates field-specific application recommendations based on real soil data. Laboratory analysis is carried out by SoilView. All farmer data is anonymised and passed to Iowa State University to support multi-year nitrogen modelling across the state's key watersheds.

Iowa Agriculture Secretary Mike Naig described the initiative as "a financial and environmental win at the same time." The programme is set to expand before the end of the year to cover the Boone, Des Moines, Middle Cedar, and Raccoon River watersheds.

How broadly farmers adopt the testing, and whether the data yields actionable guidance across different soil types and growing conditions, will determine the programme's long-term value. Those questions will take more than one growing season to answer.