Potassium isotherm partitioning based on modified quantity-intensity relation and potassium buffering characterization of soils of North India

a:4:{i:0;s:137:"Background: Potassium (K) availability in soil and plant uptake is restrained by the dynamic interactions among the different pools of K.";i:1;s:410:"Aims: To understand these interactions, a study was undertaken to assess the quantity-intensity (Q/I) and buffering characteristics of rainfed maize (Zea mays L.) growing soils. Ten contrasting soils were evaluated for K partitioning changes in exchangeable K (Delta EK) and non-exchangeable K (Delta NEK) pools in the soil-solution phase and buffering characteristics using a modified version of Q/I approach.";i:2;s:1056:"Results: The partitioned Q/I isotherms showed strong adsorption with the increase in K concentration ratio (CRK) and the changes due to Delta EK were higher than changes due to Delta NEK. Total buffering capacity (PBCK) significantly correlated (r = 0.92, p <0.01) with clay content with a major share contributed by buffering capacity owing to non-exchangeable K ( PBC Delta NEK K ) rather than exchangeable K ( PBC Delta EK K ). The fixation capacity (beta) factor, the magnitude of added K converted into a non-exchangeable pool, ranged from 41 to 63%, whereas release (alpha) factor, the magnitude of added K converted to the exchangeable pool, ranged from 19 to 36%. Both threshold solution K (CKr) and threshold exchangeable K (EKr) values were found to be high in Satran clay loam (S2) and lower in Doon silty clay loam (S3) soils. The equilibrium exchangeable K (EKo) was found close to minimum exchangeable K (E-min) in Doon silty clay loam (S3) and Babaweyl sandy clay loam (S1) soils and overall E-min constituted about 8.94 to 0.57% of the EKo.";i:3;s:402:"Conclusion: It may be concluded that K Q/I isotherm partitioning provides a valuable insight to assess the dynamic relations. The ratio of alpha/beta (K recharge index) could be used to evaluate the K enrichment capacity of soil to K additions while EKr and E-min can be potentially useful in the elucidation of exchangeable K as K fertility index especially in soils with poor K fertilizer management.";}