Effect of Plant-Available Stored Soil Moisture on Corn Yield: II. Variable Climatic Conditions
1974
Leeper, R. A. | Runge, E. C. A. | Walker, W. M.
Agronomists have long been interested in how variation in soils and climate are related to crop yields. An experiment was conducted to quantify the effect of weekly plant available stored soil moisture (PASSM) during 10 weeks of the growing season on corn (Zea mays L.) yield under constant and variable climatic conditions. The objective of this study was to determine how much of the variation in corn yield was due to variations in soils and climate and to develop a model relating corn yield to soil, rainfall, and temperature which could be used to predict corn yields for other locations not studied. Plot yields from four Illinois locations (farms) for 3 years (1969–1971) were correlated with weekly PASSM, rooting depth, or available water holding capacity in the rooting zone and climatic data (rainfall and temperature). Experimental plots had high fertility and management. Weekly PASSM, rainfall, and temperature values were summed by a method similar to Fisher's polynomial technique as previously modified. Differences in corn yields due to soils, locations, and among years within locations are due to differences in climate (rainfall and temperature) and differences the ability of the soil to supply water. When correlated with rainfall and temperature data PASSM determined on a weekly basis was slightly less efficient (R² = 0.80) than was rooting depth (R² = 0.83) or amount of preseason water available in the rooting zone (R² = 0.81) in explaining variations in corn yield. Equations fitted to the data should be useful models in predicting corn yields for other locations and soil conditions not studied. The model utilizing the amount of preseason water available in the rooting zone is particularly easy to utilize in predicting corn yield for other locations from soils and climatic data.
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