Anionic Effects on Potassium Reactions in Variable-Charge Atlantic Coastal Plain Soils
1991
Sadusky, M. C. | Sparks, D. L.
To better understand the role anions play in the rate of cation adsorption, the effect of anions on K mobility, retention, and rate of K reactions in two variable-charge Atlantic Coastal Plain soils was investigated. The soils studied were a Rumford loamy sand (coarseloamy, siliceous, thermic Typic Hapludult) and a Kenansville loamy sand (loamy, siliceous, thermic Arenic Hapludult). The effects of ClO₄, Cl, SO₄, PO₄, and SiO₃ on the rate and magnitude of K adsorption on the two soils was investigated at pH 5 and 6 using a stirred-flow kinetic technique. The type of anion present had little, if any, effect on the rate of K adsorption, but had an effect on the amount of K adsorbed. In general, the amount of K adsorbed in the presence of a particular accompanying anion was of the order SiO₃ > PO₄ > SO₄ > Cl > ClO₄. When SiO₃ was the accompanying anion in a 20 mg K L⁻¹ solution, K adsorption on the Rumford soil was as high as 358 mg K kg⁻¹, vs. a K adsorption maximum of only 58 mg K kg⁻¹ when ClO₄ was the accompanying anion. Likewise for the Kenansville soil, the SiO₃ maximum was 321 mg K kg⁻¹ while the ClO₄ maximum was only 89 mg K kg⁻¹. These studies demonstrate the role anions play in K retention and mobility, specifically on variable-charge Atlantic Coastal Plain soils. Published as Miscellaneous Paper no. 1342. Contribution no. 280 of the Dep. of Plant and Soil Sciences, Delaware Agric. Exp. Stn.
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