Physical characterization of soils under different land use systems using non-limiting water range as a soil physical index

The long-term effects of different land use systems viz., live stock-based fodder agriculture, food agriculture, agro-forestry, shifting cultivation and natural forest on physical characteristics of soils were studied. These systems were developed on sloppy land (30–50% slope) at ICAR Research Complex for NEH Region, Umiam, Meghalaya, India in 1984. The soils were acidic in reaction and clay loam in texture. After 18 years, the surface soil pH varied between 4.8 to 5.2 and organic carbon 2.10 to 3.07% under different land use systems. Bulk density of soil increased by 3.1 to 26.59% over the natural forest. Volumetric moisture content of the soil at 10% air filled porosity was maximum in natural forest and minimum in shifting cultivation whereas reverse trend was recorded at 2 MPa soil penetration resistance (SPR). Lower soil water content associated with 10% air filled porosity and higher water content associated with limiting penetration resistance of 2 MPa resulted in lower non-limiting water range (NLWR) of 6.5% for shifting cultivation as compared to food agriculture (9.7%), fodder agriculture (11.6%), agroforestry (14.8%) and natural forest systems (20.5%). The plant available water capacity (PAWe) showed slight variation (16.8 to 18.7%) under different land use systems. The NLWR:PA WC ratio was also lower in shifting cultivation as compared to other land use systems. Negative correlation was recorded between NLWR and soil erosion.