Adsorption curves and phosphorus requirements of acid soils
1980
KUNISHI, H. M. | VICKERS, J. C.
Four acid, low-phosphate soils from the southeastern United States were limed at four levels and amended with phosphorus (P) at five levels. Barley was grown for 60 days on these amended soils in the greenhouse. Plant yields and P uptake were measured.With these same amended soils, 24-hour equilibration P adsorption curves and equilibrium phosphate concentrations (the P concentration supported in solution by a soil at near field moisture capacity) were determined. The greenhouse and laboratory data were used to develop a two-point adsorption-curve method for estimating soil P additions to correct P deficiencies. The method is simple and includes the use of a correction factor that relates the amount of fertilizer P a soil adsorbs during the first 24 hours of addition to the amount the soil adsorbs during a growing season. Correction factors were estimated for the four soils, each at four different pH levels, on the basis of the lowest equilibrium phosphate concentration that supported 0.25 percent P in barley tissue.
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