On-farm evaluations of nitrogen management for corn production with precision farming technologies
Guidelines, or recommendations, for nitrogen (N) management in the Corn Belt are important to corn producers because fertilizer N must be applied for profitable corn production, because profit margins are narrow, and because N fertilization has been linked to local and regional water quality problems. Producers rely on these recommendation because it has been impractical for individuals to identify optimal rates, times, and methods of N fertilization for corn. Precision farming technologies, however, enable organized networks of crop producers to evaluate management practices used on their farms and within regions. These technologies and on-farm trials were used to assess optimal rates of spring-applied and sidedressed N, assess the benefits of using a nitrification inhibitor, and assess the ability of injected liquid swine manure to supply N needed for corn growth. The results showed optimal rates of N were less than currently recommended rates, nitrification inhibitors did not increase profits for producers in central Iowa, and injected liquid swine manure at normal rates supplied adequate amounts of N for plant growth. The results suggest that current recommendations could be substantially improved. The results document that organized networks of producers working together can evaluate and improve nitrogen management and thereby increase their profits while reducing environmental problems associated with N fertilization.