Corn response to spatial variability of residual potassium
1989
NDIAYE, J. P. | YOST, R. S.
Lack of uniformity in soil physical and chemical characteristics is one of the main causes of variation in crop productivity. We investigated the effect of nonuniformity (spatial variability) of residual K on corn response in field conditions. Corn growth was strongly related to both the level and spatial variability of soil K. Increased variation of residual K from CV = 37.0% to CV = 48.5% resulted in yield losses and an increase in the critical level of exchangeable K from 0.16 to 0.24 cmol(+) ± Kg. Decrease in yield due to spatial variability of soil K was quantitatively expressed by the variability response index (VRI), i.e., the product of the variance of soil K and the second derivative of yield with respect to exchangeable K obtained under a relatively uniform distribution of soil K. The variability response index shows promise as a way to estimate crop loss due to excessive variability. There was a gradual decrease in the correlation coefficient between corn yield and ear leaf K with increasing spatial variability of residual K.
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