Spatial Perspectives Corn and Soybean Yield Progress.

In resent times there has been a growing interest improving corn grain and soybean seed yield progress. Yield progress is often reported for large regions or the entire USA. Thus, these yearly trend analyses combine the spatial yield variation and temporal yield variation. The intention of this study is to evaluate yearly yield trends at a county spatial scale by analyzing corn and soybean yield progress in a county by county basis, using NASS county yield data form the year 1970 to 2006. The analysis made possible not only to separate temporal and spatial sources of yield variation but also to recognize that areas of the greatest performance are not always the areas with the greatest yield progress.