Potassium release characteristics of some soils of Uttar Pradesh hills varying in altitude and their relationship with forms of soil K and clay mineralogy

Abstract

Release rates of non-exchangeable potassium were determined for 15 soils occurring widely in different altitude in intensively cultivated soils of U.P. hills. For this, the method of Oliver and Diarisso [Oliver, R., Diarisso, D., 1985. Cine tique de dissolution du potassi um de divers soils per allaque a chaud a Li acide nitrique normal c.r. ATP Dynamique des cations, Bull. CIRAD Montpellier, France Section, N: 1–13.] was adopted involving successive extraction contact duration with 1 N HNO 3 as an extractant on water bath at 85°C. The soil series were then grouped under three classes with respect to altitude and exchangeable K contents, namely, 1250, 1650 and 2250 m AMSL with exchangeable K group 40±5, 90±15 and 140±15 mg kg −1 soil, respectively. The cumulative K release decreased with increase in altitude and exchangeable K content and the values ranged from 473 to 527, 300 to 336 and 235 to 287 mg kg −1 soil, respectively. All values of the initial linear rapid K release part ( P 1) and subsequent slow K release part ( P 2) indicated that P 1 is generally greater than P 2 and the values of P 1 and P 2 decreased with increase in altitude. Hence, it is advisable to consider the amount of exchangeable K, non-exchangeable K content and clay mineralogy while recommending the potassium fertilizer in different altitude.