Are the soil properties and organic carbon stocks influenced by different land use systems in tropical semi-arid region, India?

Abstract

Different land uses significantly affect soil properties due to variations in organic matter addition, decomposition, and stabilization. A study assessed organic carbon stock in soils from various landforms and its use in granite-gneiss and schist geological settings in the semi-arid Chitradurga district, Karnataka. Nine soil profiles (pedons) from upland areas and four from lowland areas were analyzed. Soil characteristics such as pH, electrical conductivity (EC), organic carbon (OC), clay content, bulk density (BD), cation exchange capacity (CEC), base saturation, and calcium carbonate equivalent (CCE) were measured. The results showed a pH range from 6.09 (slightly acidic) to 9.74 (very alkaline) with non-saline soils (EC < 2 dS m-1). Organic carbon levels varied from 1.40 to 7.30 g kg-1 in the surface layer and 1.10 to 8.50 g kg-1 in the subsurface layer. Clay content ranged from 6.92% to 53.52% (surface) and from 9.83% to 64.81% (subsurface). Bulk density ranged from 1.31 to 1.98 Mg m-3 (surface) and 0.78 to 1.89 Mg m-3 (subsurface). Cation exchange capacity spanned from 3.44 to 53.14 cmol (p+) kg-1 (surface) and from 4.92 to 57.93 cmol (p+) kg-1 (subsurface). Base saturation was between 37% and over 100%. Organic carbon stock ranged from 0.33 to 1.95 kg m-2 (surface) and from 0.23 to 5.46 kg m-2 (subsurface). Fallow land and sapota plantations had higher organic carbon stocks than agricultural lands, with coconut and banana plantations following. Most pedons had low organic carbon content, were alkaline, calcareous, and experienced moderate to severe erosion. To address these issues, implementing management practices like reclamation, irrigation, organic manure application, and soil conservation measures is critical for improving crop yield, controlling erosion, and maintaining soil health and sustainability.