Adapt-N Maize Nitrogen Management Tool: Lessons Learned from Long-Term Field Trials in Iowa and New York.

Achieving high nitrogen (N) efficiency in humid environments is challenging as denitrification and N leaching losses may occur due to the complex interactions of weather, soil type, hydrology, and crop N uptake. This in turn could lead to crop N deficiency and reduction in yield. In response, farmers regularly apply excessive N fertilizer to account for these weather effects, increasing both the farmer’s expenses and environmental costs. Adapt-N is a web-based cloud-computing maize N management tool, based on simulation modeling of the relevant crop and soil processes throughout the growing season. The tool, currently calibrated for the US Northeast, Midwest and Southeast regions, uses near-real-time weather data to estimate optimum in-season N application rates for maize. Incorporation of high-resolution weather data allows for the generation of precise and adaptive daily N application recommendations to maximize field-level yield. This study presents a validation of the tool using 125 replicated strip trials across Iowa and New York conducted during the years 2011 through 2014, which experienced widely ranging growing season precipitation. In each trial, crop yields resulting from the application of the Adapt-N recommendations were compared with those based on the grower’s regular practice. The results suggest that employing Adapt-N leads to an average reduction of 46 kg/ha (26%) in N applied, without compromising crop yields. This reduction led to a net increase of 60$/ha in the farmers profit while reducing environmental N losses. The ability of the tool to account for weather induced crop N deficiencies was emphasized during the unusually wet spring season of 2013 in New York, where Adapt-N generally recommended higher N inputs than the farmer regular practice, leading to increased yields and profits (an average of 212 $/ha). These results indicate the Adapt-N tool can increase the sustainability of maize crop management.