Mitscherlich‐Bray Equation Used to Correlate Soil Phosphorus and Potato Yields

Abstract

Abstract 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.