Fertility Status, Potassium Fractions and Acidity Nature of the Soils of Mon District, Nagaland in Relation to Land Uses

摘要

Ninety soil samples (0-15 cm) were collected from fifteen villages of Mon district of Nagaland to study the influence of different land uses on some important physicochemical properties, fertility status and fractions of potassium (K) and nature of soil acidity. Results revealed that the soils were strong to moderately acidic in reaction and quite low in cation exchange capacity (CEC). The forest soils showed higher CEC than that of cultivated soils. Almost similar sand, silt and clay contents were recorded in cultivated and forest soils. In general, both soils were high in organic carbon (OC), medium in available nitrogen (N) and К and low in available phosphorus (P). Soils of both land use indicated high nutrient index values for OC, medium for Nand K and low for P. Forest soils contained high amount of OC, available N, P and K than cultivated soils. Available N, P and К were significantly and positively correlated with OC. Available P had significantly and positively correlated with soil pH.The fractions of K were high in forest soils. However, available K, water soluble K, exchangeable K and non-exchangeable К constituted 14.5, 0.9, 13.6 and 85.6% in cultivated soils and 14.7, 0.9, 13.7 and 85.2% in forest soils towards HNO_3 extractableK, respectively. Non-exchangeable K and HNO_3-K were significantly and positively correlated with clay content of the soil. Total potential acidity of the soils was quite high and accounted for severe acidity problem in these soils. Reasonable quantity of various acidity forms was reported in the soils. Quantum of various forms of acidities was high in cultivated soils except exchangeable H~+. Most of the acidity components were significantly and positively correlated with OC and CEC and significantly and negatively correlated with soil pH.