| Popis: |
Asoil Productivity Index (PI) based on bulk density, pH, and plant available water holding capacity was evaluated on a set of artificially eroded plots on a claypan soil. The plots had topsoil depths of 0, 125, 250, and 375 mm and were fertilized for a corn yield goal of 11.2 Mg/ha. Data were collected for 1984 and 1985. Corn yields in 1984 and 1985 were very different because the weather was dry in 1984 while in 1985 there was adequate rainfall. The PI was compared with the depth to clay and depth of topsoil as a predictor of corn yield. Neither depth to clay nor depth of topsoil explained as much yield variation as the PI. The depth to clay variable was not significantly correlated to yield in the wet year. The PI was a significant yield predictor and was better in the drought year than the year of adequate rainfall (R^ = 0.72 and R^ = 0.63, respectively). Total crop water use between July 1 and August 31, when coupled with the PI, predicted 82% of the variation in yield from both years. |
