Relationship between the quantity and intensity of potassium in some maize soils of central Kashmir (India)

Plant K uptake depends on its intensity, capacity and removal rate of soils which can be modeled using K exchange-equilibrium obtained from quantity-intensity (Q/I) isotherms i.e. activity ratio at equilibrium (ARe^K), labile K (KL), potential buffering capacity (PBC^K) and free energy change (−ΔG). These relations were studied in five major maize growing soils of district Ganderbal (Kashmir, India). ARe^K ranged from 0.26 to 1.21 x 10⁻³ (Mol L⁻¹)^0.5, KL from 0.26 to 0.67 cmolc kg⁻¹, PBC^K from 23.2 to 37.6 cmolc kg⁻¹/(Mol L⁻¹)^0.5 and -ΔG from 3.98 to 4.81 K cal mol^−1oK⁻¹. ARe^K was found significantly correlated with clay (r = 840**) and K0 (r = 988*). Magnitude of labile K (K_L), K held on non-specific sites (K₀) and specific sites (K_X) were higher in Sumbal silty clay. The negative values of ΔG indicated that K- (Ca + Mg) exchange in all the soils was spontaneous.