Effects of Spatial Variability of Nitrogen, Moisture, and Weeds on the Advantages of Site-specific Applications for Wheat

Abstract

Field data for moisture, nitrogen, and weeds were collected at 1-m intervals to form a basis for evaluating the differences between spatially modulated applications and blanket applications of water, nitrogen, and herbicide. Simulated advantages in terms of efficiency of input use were obtained with spatially variable applications mainly at low and intermediate application rates, and in the case of irrigated winter wheat such advantages amounted to 2, 12, and 40% for water, nitrogen, and herbicide, respectively. Advantages decreased with sampling and response intervals longer than 1 m.