Corn yield in relation to soil, management, and weather variables in western Iowa

Abstract

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Selection of management variables for regressing Iowa corn yields on management, climatic, and soil variables

“…Its presence also altered the effects of other variables on yield. Pena-Olvera (1979) reported a high correlation between the barren plants variable and yield (r = -0.46) but it had no meaningful inter correlation with the other management variables that he studied. This lack of intercorrelation may be because the highest amount of barrenness is related to two or more variables, including moisture stress.…”

“…In data from Western Iowa, Pena-Olvera (1979) failed to get a significant effect of root lodging on yield in his final regression on soil and man agement variables. Manu (1979) retained the root lodging variable although its regression coefficient was significant at only the 15% level.…”

“…Previous studies of regressing Iowa coim yield on management, climatic, and soil variables will be reviewed primarily; these studies were by Morris (1972), Henao (1976), Pena-Olvera (1979), and Manu (1979) who used the same data as were used in this study. The major objective of this study was to examine the management variables in more detail than the previous investigators had done.…”

“…Henao (1976) found that the root damage rating had a significant negative effect on corn yield primarily through a highly significant interaction with soil test P of the plow layer. Pena-Olvera (1979) reported a highly significant, negative, linear effect of root damage rating on yield modified by significant interactions with years (trend), slope of the site, and organic carbon content of the plow layer. Signifi cant interactions between corn root damage rating and date of planting.…”

“…The remaining group of variables that needed to be studied in detail were the management variables along with the recomputed climatic indexes based on the research of Pena-Olvera (1979), using data from all 15…”