Calcium-Potassium Interactions in Soils and Plants: I. Lime-Induced Potassium Fixation in Mardin Silt Loam
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Date
1953-01
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Abstract
Relatively large amounts of potassium were fixed in nonexchangeable forms upon addition of CaCOs to acid Mardin silt loam. This fixation occurred in moist soil and was independent of the potassium fixation that took place when the soils were dried. Hydrogen-saturated Mardin silt loam was found to fix no potassium upon moist storage. Fixation by this soil increased in direct relation to the increase in pH. Lime-induced K fixation apparently is not an instantaneous reaction, since the fixation of potassium by the Mardin soil increased throughout 24 weeks of moist incubation. There was no evidence that lime-induced K fixation was related to increased rhicrobidl activity. No direct relationship between the amount of potassium entering the exchange complex and the amount fixed by moist .soils was found. Although additions of lime up to 78 per cent base saturation resulted in a reduction of both water-soluble and exchangeable potassium, the presence of excess CaCO3 further reduced the exchangeable potassium while increasing the concentration of potassium in a water extract. Calcium sulfate had no effect on the level of exchangeable potassium but increased tn<& water-soluble fraction. *• The potassium fixed in limed soils upon moist storage as determined by leaching with neutral ammonium acetate was found to be released upon a subsequent.leaching with N ammonium acetate, pH 4.8. Furthermore, there ^was no evidence of lime-induced fixation when the soil was leached directly with the extraction solution at pH 4:8.