Spatial Optimization of Nitrogen Application For Dryland Wheat Yield and Protein

Dryland wheat farming is reliant on nitrogen (N) application to increase the protein content and yield of a given year’s harvest.  The percentage of protein and amount of yield determine the farmer’s gross revenue, however there are additional factors that may influence this seemingly simple relationship.  Limited amounts of plant available water can decrease the yield, yet increase the protein percentage.  Other variables have also been shown to spatially influence the yield and protein content such as tillage system, landscape attributes (slope, aspect, elevation, etc.) soil type and history of management .  Given the complex spatial and temporal variability in soil water and other variables, it is very difficult to understand where and how much nitrogen the farmer should apply to maximize their net revenue.  This study will attempt to clarify these relationships within a modeling framework, building knowledge and producer accessible tools to improve nitrogen fertilizer management on dryland wheat farms in Montana.

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