A Basic Study of Potassium Fertilizer Placement Effects on Potassium Uptake by Cotton

G.L. Pate, G.L. Mullins, and C.H. Burmester


Recent studies of potassium (K) fertilization of cotton have concentrated on the deep placement of K to deter late season K deficiencies. Little is known, however, about the efficiency of the cotton plant in removing K from various positions in the soil profile. In 1992, a field study was initiated to determine the cotton plant's ability to remove K from the soil. On two Ultisols in Alabama, K as a KCl solution and Rb as a RbCl solution was injected into mini-plots at depths of 0, 3, 9, 15, and 21 inches. Select combinations of each depth were also included. A test rate for K of 120 lb K2O/A was applied. Whole plants were harvested by plot, fractionated, and K accumulation measured for each plant part. Potassium uptake was maximized in 1992 when the greatest proportion of the soil profile received K fertilizer. However, there were no significant differences (P<0.10) observed among surface applied and deep applied treatments for each location in 1992. Total K uptake data for 1993, however, did show a significant difference (P<0.10) among treatments for a Lucedale sandy clay loam soil. Root length density measurements were not significantly different (P<0.10) for surface applied or deep applied K.

Reprinted from Proceedings of the 1994 Beltwide Cotton Conferences pp. 1520 - 1523
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998