Use of Computer Simulation Models and Databases for Nitrogen Recommendations for Corn.

Nitrogen management in maize production is often imprecise and inefficient in humid regions due to dynamic, complex and locally-specific interactions among weather, soil and management variables.   N losses are strongly impacted by spring weather, which accordingly requires adjustment of supplemental N rates based on other site-specific factors.   Computer simulation models can use weather information to simulate soil C and N transformations, water transport and N uptake during maize growth to calculate N fertilizer needs.  Two computational tools are currently available for maize nitrogen management, Adapt-N and Maize-N.  They both rely on information related to the management of the maize crop, soil properties, rotations, tillage, fertilizer management, and manuring.  The models both provide uncertainty estimates, adjust for fertilizer and grain prices, and provide additional diagnostic simulation results. Maize-N primarily relies on historical weather data for long-term optimization, and the software is downloaded onto a personal computer.  Adapt-N focuses on real-time optimization and is a web-accessible server-based tool that includes high resolution climate data on a 5x5 km grid a readily accessible web-interface that is also mobile enabled.   Maize-N estimates optimum N rates based on a combination response curve – N credit approach, while Adapt-N uses a combined deterministic (pre-sidedress) and stochastic (post sidedress) mass balance approach.  From beta-testing with strip trials, the Adapt-N tool increased grower profits on average by $35/acre, and N losses to the environment were decreased by 5 to 120 lb/acre.