Availability and Fixation of Added Potassium in Two California Soils When Cropped to Cotton
1963
Page, A. L. | Bingham, F. T. | Ganje, T. J. | Garber, M. J.
Field studies have recently demonstrated the occurrence of K deficiency in California cotton fields, and, further, unusually high rates of K fertilizers were required to correct the deficiencies. A greenhouse and laboratory study demonstrated that fixation of the added K was the reason high K applications were required. Two soils from problem fields were treated with K at rates ranging from 0 to 400 ppm. K and cropped to cotton in the greenhouse. Response, as indicated by plant analyses, plant symptoms, and yields, was not obtained until the application rate equaled or exceeded 160 ppm. K. Exchange and Rb-fixation capacities of the soils after cropping showed a progressive decrease as a function of the added K. Disregarding the K removed by the crop and assuming the decrease in exchange capacities was due exclusively to K fixation, 63 to 75% of the added K was fixed. Laboratory studies demonstrated that soils in the moist state would fix up to 900 ppm. K against neutral salt removal. The effect of the added K on the Mg content of the cotton plant is also reported.
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