2 Crop Yield Mapping: Comparison of Yield Monitors and Mapping Techniques

Although the variability in soil nutrients and crop yields has been well documented since the turn of the century (Robinson & Lloyd, 1915; Fairfield Smith, 1938), the mechanization of agriculture and the trend to larger implements has led to larger areas being treated as a single unit. Recent advances, however, in machine technology and improvements in data management have made it possible to reverse this trend by implementing site specific crop management (Goering, 1993). The implementation of spatially selective field operations is dependent on field mapping of the variations in soil and crop parameters (Stafford et aI., 1991). The mapping of crop yield is especially important since the recommendation rates for many inputs are determined by the yield goal, and yield maps are necessary to assess the effects of site specific crop management. Since yield maps may be used both for the determination of management inputs and to evaluate the results of these strategies, it is important that the accuracy of the yield map be considered. Recently, continuous grain flow monitors in conjunction with speed sensors and location systems have been used to develop crop yield maps (Searc