Pecan [Carya illinoensis(wangenh.) C. Koch] yield, leaf and soil analysis responses from different combinations of nitrogen and potassium application

Abstract

Abstract Nitrogen rates of 112 and 224 kg/ha and K rates of 0, 56, 112, 168, and 224 kg/ha were applied to young ‘Desirable’ trees annually in order to determine leaf concentrations for optimum pecan yield and to measure their effect on other leaf minerals and the resulting effect on soil analysis. Yield was not affected significantly by treatments within any individual year of 11 years; however, when data were combined over years, yield was greatest at the 56 kg/ha rate of K and decreased at lower and higher rates. The decrease in yield with increasing K rates was smaller for the high than for the low N rate. Doubling the N rate increased leaf N only slightly, but increased leaf Cu and reduced soil pH, Ca, and Mg. Increasing K application had very little effect on leaf N. This study indicates that a lower leaf analysis threshold for the sufficiency range of 0.75% for K and 2.50% for N would be satisfactory for ‘Desirable’.