USING REGIONALIZED VARIABLES TO ESTIMATE FIELD VARIABILITY OF CORN YIELD FOR 4 TILLAGE REGIMES

In selecting an appropriate tillage system for a specific crop and field, it is desirable to choose one that maximizes yield for the field as a whole; however, various areas in a field often give different responses to the same tillage system. The theory of regionalized variables was used to evaluate corn left bracket Zea mays L. right bracket grain yield response to the following four tillage systems (tandem disking, tandem disking followed by bedding, in-row-subsoiling and bedding, and chisel plowing). These treatments were randomized, replicated three times, and stripped across the 198-m-long field of Norfolk soil (Typic Paleudults), which had a tillage pan and variable depth to B horizon. Grain was harvested in adjoining 15. 2-m-long plots in each strip. Analysis of directional semivariograms for relative corn grain yield in the along-the-row direction, showed a different variance structure for each tillage treatment.