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This article in SSSAJ

  1. Vol. 54 No. 5, p. 1356-1361
     
    Received: July 10, 1989
    Published: Sept, 1990


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doi:10.2136/sssaj1990.03615995005400050026x

Potassium Supply Characteristics of Thirty-three Soils as Influenced by Seven Rates of Potassium

  1. J. L. Kovar and
  2. S. A. Barber 
  1. Dep. of Agronomy, Louisiana State Univ., Baton Rouge, LA 70803
    Dep. of Agronomy, Purdue Univ., West Lafayette, IN 47907

Abstract

Abstract

Limited information is available on the effect of applications of multielement fertilizer materials on the concurrent changes in Kl (soil-solution K) and Ks (exchangeable K). The objectives of this research were to: (i) investigate the relative increases in both Kl and Ks after addition of graded amounts of a 3-4-7.5 solution fertilizer; and (ii) determine if the changes in Kl and Ks with fertilizer additions were related to some measurable physical or chemical property of the soil. Thirty-three surface soils were equilibrated moist for 3 wk after addition of 0, 21, 42, 104, 208, 415, and 1245 mg K per kg of soil. High rates of application were used because they occur when the same total amount of K is placed in a small fraction of soil, e.g., band application. Values of Kl were determined from water-displaced soil solution. Values of Ks were obtained from K extracted with 1.0 M NH4OAc at pH 7.0 minus θKl, where θ is the volumetric water content g−1 of sample. The increase in Kl with K addition was described by Kl = axc + d, where x is the amount of added K and a and d are regression constants. Values of c, the curvilinearity coefficient, varied from 1.00 (linear) to 1.59. The increase in Ks with K addition was described by Ks = g + hx. The value g represents the amount of exchangeable K in the untreated soil. Values of h, the slope, varied from 0.42 to 1.13. The coefficients describing the relation of both Kl and Ks to added K were not correlated with any of the measured soil properties. There was no significant correlation between c and h. Characterization of the changes in Kl and Ks after addition of K gives information useful for determining the effectiveness of K placement.

Contribution from Purdue Univ. Agric. Exp. Stn. This research was supported in part by a grant from the Fluid Fertilizer Foundation. Submitted as Purdue Journal Paper no. 12078.

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