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Iowa updates its strategy to reduce nutrient runoff
(Des Moines, Iowa) – The Iowa Nutrient Reduction Strategy has been updated to reflect increased access to data and new practices, including a precision ag tool to optimize nitrogen application. According to the Iowa Capital Dispatch, the nutrient reduction strategy was developed by the Iowa Department of Agriculture and Land Stewardship, the Iowa Department of Natural Resources, and Iowa State University in 2013, as part of a larger, 12-state task force to address the growing size of the hypoxia in the Gulf of Mexico by reducing nutrient levels in the Mississippi River Basin.
The strategy encourages farmers to participate in the nutrient reduction strategies but does not mandate the conservation practices. IDALS announced the updated version of the strategy Thursday. According to the press release, the last update was completed in 2017. Excess nitrogen and phosphorus are the main contributors to the “dead zone” in what was formerly know as the Gulf of Mexico, and therefore are the nutrients the strategy seeks to reduce.
One of the 2025 updates includes a recommendation that corn farmers follow a three-year extended rotation to reduce nitrateR08;N concentration in tile drainage by 42%, on average. According to the plan, that means following a four-year schedule of corn, soybean, alfalfa and alfalfa in a given field. Three years of legumes, a type of plant that fixes nitrogen in the soil, will reduce the need to apply nitrogen to the corn crop, and showed a 10% increase in corn yields.
The recommendation would help the state reach its goal of reducing the nitrogen load from non-point sources by 41% from the 1980-1996 benchmark nutrient levels. Point source pollution comes from sources like a wastewater facility or a factory that directly discharges into waterways. Non-point pollution is not as easy to pinpoint as it includes runoff from agricultural land, urban areas and more.
The update also notes that INRS provides quarterly updates to an online dashboard with measurements of water quality metrics, erosion control practices, funding, point source facility permits and in-field practices, instead of a “static” annual report. The Iowa Nutrient Research and Education Council, which monitors the progress of the strategy, found in its 2023 survey a 7% decrease in the use of commercial nitrogen applied to continuous corn operations and that farmers planted nearly 4 million acres of cover crops in 2023, which is also a practice promoted by the strategy to reduce nutrient runoff.
The press release from IDALS also highlighted new strategies to implement conservation practices. This included the “batch and build” process which began in 2020. The process installs nutrient reduction practices, like saturated buffers and bioreactors, on multiple farms at once, to maximize funding pools and accelerate the adoption of these practices. According to IDALS, the state has completed five “batches” so far.
The strategy is also promoting the use of the Nitrogen Fertilizer Application Consultation Tool, or N-FACT, a precision ag tool developed by the Iowa Nitrogen Initiative, to “fine-tune” fertilizer application. The public, online tool helps farmers determine the optimal rate of nitrogen application for their farm based on factors like location, precipitation, and residual nitrogen.
The Iowa Nitrogen Initiative developed the tool from ISU research conducted with private farmers in every region of the state. According to a press release from IDALS, N-FACT can calculate more than 21,000 optimal nitrogen rate scenarios due to the hundreds of field trials conducted by ISU.
