Land Use Change Alters Soil Physico-Chemical Properties in Manipur, Northeast India

Abstract

Land-use change is a major driver of soil degradation in tropical ecosystems, influencing soil organic carbon (SOC), nutrients and ecosystem productivity. This study evaluated the effects of five contrasting land-use systems, namely natural forest (NF), degraded forest (DF), fallow land (FL), pine plantation (PP), and paddy field (PF), on soil physico chemical properties in Manipur, Northeast India. Soil samples were collected from all land use types to a depth of 1 m and divided into four layers (0–15, 15–30, 30–60, and 60–100 cm). Soil samples were analyszd for soil bulk density, moisture content, texture, texture, pH, SOC, available nitrogen (Navail), phosphorus (Pavail), and exchangeable potassium (K+), calcium (Ca), and magnesium (Mg). Two-way ANOVA revealed significant effects of land-use type, soil depth, and their interaction on most soil properties (p < 0.001). Natural forest soils maintained the highest SOC, Navail, and moisture content. Fallow land exhibited soil properties comparable to those of NF, indicating substantial recovery of soil fertility during secondary succession. In contrast, pine plantation soils showed the lowest SOC and available P, associated with acidic conditions and slow decomposition of conifer litter. Paddy fields were characterised by higher pH, K+, Ca, and Mg due to prolonged flooding and management practices. Soil nutrient concentrations and moisture content declined significantly with increasing depth, whereas bulk density increased. Principal Component Analysis explained 73.28% of the total variance and clearly distinguished land-use systems based on their soil properties. The findings demonstrate that land-use conversion substantially alters soil physicochemical properties and highlight the importance of maintaining natural forests and promoting fallow-based restoration strategies to sustain soil fertility and ecosystem functioning in tropical landscapes.