Effect of Different Land Uses on Soil Pedogenic properties and Sodicity Development in Krishnagiri Reservoir Project Dam Catchment in Tamil Nadu.

Abstract

Over-exploitation of natural resources in agricultural system has resulted in poor crop productivity and unsustainable growth. Land use has changed over a period mainly based on irrigation, which has enhanced agricultural productivity, whereas excessive irrigation degraded soil quality and ecosystem. Paddy ecosystems in catchment area and river basins are suspected to be prominent sites for soil degradation, demanding a detailed study to understand the changes in soil quality on excess irrigation. Based on that, three different ecosystems were identified in dam catchment viz. double crop paddy (DCP), single crop paddy (SCP) and non-paddymango (NP) to assess changes in different soil pedogenic properties over a period of 60 years under irrigation. The clay content varied from 24.7 to 37.6, 10.7 to 32.2 and 14.6 to 38.3% in DCP, SCP and NP, respectively. Among the systems, clay content gradually increased with increasing depth of the profiles. Lowest bulk density (1.23 Mg m-3) was observed in SCP system. Soil reaction (pH) was slightly alkaline to moderately alkaline and this was observed in surface soils of DCP and SCP, whereas NP was neutral to slightly alkaline. EC varied with different horizons; high salt concentration was found (0.53 to 0.61 dS m-1) in lower horizon of DCP. The SOC values were varied between different ecosystems, surface horizons of DCP recorded higher (1.35%) SOC than NP soils (0.20%). ESP was higher in paddy (DCP-10.09%; SCP-20.73%) than non- paddy soils (5.98%). Excess irrigation and continuous inundation in dam catchment resulted in increased salt concentration in different depths of the soils.