Crop Response to Different Soil Fertility Levels in a 5 by 5 by 5 by 2 Factorial Experiment: I. Corn
1956
Hutton, C. E. | Robertson, W. K. | Hanson, W. D.
Four years' data are reported for a 5-level NPK factorial experiment with 2 levels of dolomitic limestone. The experiment was conducted on Red Bay fine sandy loam in western Florida. Phosphorus showed the greatest yield response at the beginning of the experiment, but the amount of phosphorus required to give a maximum yield decreased as the experiment progressed. Nitrogen showed an excellent yield response in years when rainfall distribution was good. Potassium gave a positive response each year, with the degree of response increasing as the experiment progressed. The increase in the potash requirement was due to the depletion of soil potash on treatments which received small annual potash applications. Dolomitic limestone gave significant increases each year; these were greater at the 3-ton-per-acre rate than at lower rates. These data were fitted to general parabolic response surfaces, and equations were determined by multiple curvilinear regression techniques to describe each years results. The units of N, P₂O₅, and K₂O required to give a maximum yield and a maximum net return per acre were determined for each year reported.
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