Potassium Release from Soil Clays by Diammonium Phosphate, Ammonium Bicarbonate and Ammonium Chloride

We have studied the release of potassium (K) by diammonium phosphate, ammonium bicarbonate and ammonium chloride from Ca-saturated clay fractions of four Aridisols (Bhalwal, Gujiana, Miranpur and Pacca series), one Inceptisols (Miani series) and one Alfisol (Pindorian series). The six soil clay fractions contained mica, kaolinite smectites as their major mineral components and vermiculite and chlorite as minor constituents. Total K in the soil clays ranged from 2.65 to 3.55%. Of total K, 2–3% in the soil clays was extracted by the three extractants: diammonium phosphate, ammonium bicarbonate and ammonium chloride. However, there was significant (P < 0.01) main and interactive effect of soil x extractant on the amount of K extracted from soil clays. Potassium extracted from the soil clays was described by the Elovich equation. Amount of K extracted by the three extractants from six soil clays, except in Pindorian series, followed the order: ammonium bicarbonate > ammonium chloride > diammonium phosphate.
The profound influence of bicarbonate, chloride and phosphate anions on differential K replacement behaviour of NH₄ can be an important factor for K nutrition of plants in arid region soils.