Long-term Effect of Various Land Use Systems on Physical Properties of Silty Clay Loam Soil of N-E Hills

摘要

The shifting cultivation, predominant in N-E hills of India, has become unsustainable today primarily due to reduced jhuming cycle (2-3 years) leading to soil degradation and ecological imbalance. An investigation was undertaken to evaluate the long-term effects of different land use systems viz. agriculture, agri-horti-sirvi-pastoral, forestry, livestock based land use, natural fallow and shifting cultivation on some soil physical properties with an objective to recommend the most suitable alternative land use system for maintenance of soil physical health. There was a general increase in bulk density values with increasing soil depth in all the systems. Adoption of modified land use system like agri-horti-sirvi-pastoral system significantly increased the mean weight diameter (29.4%) and decreased the dispersion ratio (52.9%) over the shifting cultivation. With respect to the available water content under modified systems, it increased by 24.0-36.5% over the shifting cultivation. The unsaturated hydraulic conductivity [K(theta)], and soil water diffusivity [D(theta)], varied from 0.50xl0~(-6) to 11.16 cm hr~(-1) and 0.28 x 10~(-7)to 0.72 x 10~(-3) m~2s~(-1) respectively, among the various land use systems. These attributes decreased with decreasein soil water content. The periodical monitoring of soil moisture regime indicated that the agri-horti-silvi-pastoral, agriculture, and livestock based land use systems conserve higher soil moisture throughout the year as compared to other systems. On the basis of the parameters investigated, agri-horti-silvi-pastoral system appeared to be most suitable for improving the soil hydro-physical conditions and conserving soil moisture as well in the hilly agro-ecosystems of Meghalaya.