Mitscherlich-Bray Equation Used to Correlate Soil Phosphorus and Potato Yields
- F. V. Payton,
- R. D. Rhue and
- D. R. Hensel
Very little is known about the response of potato (Solanum tuberosum L.) to P in northeast Florida where potato is a major winter crop. The purpose of this study was to correlate tuber yields with Mehlich-I extractable soil and fertilizer P. Dolomitic lime was applied to an Ellzey sand (sandy, siliceous, hyperthermic Arenic Ochraqualfs) in 1977 at rates of 0.0, 2.2, 4.5, and 9.0 Mg ha−1, and resulted in average soil pH levels of 4.8, 5.4, 6.1, and 6.5 during the 5 yr of the study. In 1978 four rates of P were superimposed on lime treatments to establish a range of residual soil P levels for use in subsequent years of the study. In the following years, plots were fertilized with either no P (residual) or with P at planting. Data from 1981 were used to estimate the various parameters of the MB model, which related tuber yields to a linear function of soil and fertilizer P referred to as total effective P (TEP). Between 1979 and 1982 the percent yield was found to decrease with time by 20 to 70%, depending on the soil pH and Mehlich-I P level. The decrease in relative yield was more rapid at pH 6.5 than at 5.4. The decrease in yield appeared to be the result of a decrease in availability of residual soil P, which was not accompanied by a decrease in Mehlich-I extractable P.
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