Wheat nitrogen response conditional on past yield and rainfall: A step in improving optimal nitrogen applications

Making precision nitrogen (N) application clearly profitable will likely require incorporating multiple sources of information. Low-cost sources of information include rainfall and the previous year's yield. This paper uses data from a long-term experiment on the response of winter wheat (Triticum aestivum L.) to N fertilizer, as well as rainfall data from the University of Oklahoma's Mesonet weather station. The goal was to determine optimal topdress levels of N. A regression was used to determine the previous year's yield and rainfall on the marginal product of farmer-applied N. Information from lagged yield and rainfall increases profit by $2.79 ha^–1. Therefore, lagged yield and rainfall could be a low-cost information source to add to other sources of information to achieve the goal of widespread adoption of precision N application.