WEED AND CORN YIELD SPATIAL DISTRIBUTIONS IN REDUCED AND CONVENTIONAL TILLAGE

Abstract

Little is known about the spatial structure of weeds and of the corn yield distribution because the analysis of these variables with conventional statistical methods assume that both weed population and corn grain yield are homogeneously distributed within cropped
fields. In this research, geostatistical techniques were used to describe and map the distribution of weeds and corn yield in in response to the suppression of moldboard plowing and ridge-till as compared to conventional tillage, in 2001. It was found that corn yield and total weed population were distributed in aggregates. Exponential model provided the best fit to data of weed population after cultivation and of corn yield. Estimates by kriging were used to draw bi-dimensional maps, which showed two areas of high weed density at its southern extreme, as well as two areas of intermediate grain yield with small zones containing low and high corn yields. Spatial patterns of corn yield and weeds suggest the lack of influence of weeds on the corn yield . Long-term monitoring of weed populations and corn yield will be necessary to characterize their spatialtemporal patterns, which wight be used to improve crop management, by including the effect of tillage, the use of herbicides, fertilizers, and irrigation.