Precision Agriculture (PA) involves the management of sites or regions within a field based on local requirements rather than field average requirements. Historical best management practice involves the careful determination of best average treatment for a whole field or farm. Where there is significant variability in the resources to which management is being employed within a field, &quote;best&quote; management must also be varied in order to accommodate local peculiarities. While awareness of within-field variability is not a recent phenomenon, the ability to accurately locate (using DGPS) and revisit sites in a field, for the purpose of conducting useful quantitative measurements or treatments is only a recent development. On-picker real-time yield monitors provide the opportunity to accurately measure cottonseed yield each second during picking. When this yield information is linked to a geographic location a yield map may be produced giving the grower or agronomist quantitative data for use in evaluating the degree of variability in a field.