Using Credible Soil Loss Tolerance Value for Conservation Planning and Managing Diverse Physiographic Regions in Rajasthan

Abstract

Accelerated soil erosion degrades soil quality and undermines ecosystem functions and services. It is important to assess the severity of erosion, demarcate tolerable limits for sustainable crop production, conservation planning for soil resources, and identify the alternative land uses. Irrespective of soil type, climate and vegetation cover, the tolerable level of soil erosion in India has traditionally been taken as 11.2 Mg ha⁻¹ year⁻¹. However, this is an excessive rate for most agro-ecosystems and land uses; hence, this study aims to establish credible soil loss tolerance (‘T’ values) for some soils of western India on the basis of critical soil parameters (i.e., bulk density, infiltration rate, total organic carbon and soil reaction). The condition of a soil or ‘soil state’ (S) is defined through a quantitative model involving different soil functions. The ‘T’ values for some soils of western India ranged between 2.5 and 12.5 Mg ha⁻¹ year⁻¹ compared to default ‘T’ value of 11.2 Mg ha⁻¹ year⁻¹. About 50% of the land area has ‘T’ value >10 Mg ha⁻¹ year⁻¹, and the remaining 50% has <7.5 Mg ha⁻¹ year⁻¹, of which 13.02 M ha is having only ‘T’ value of 2.5 Mg ha⁻¹ year⁻¹. Using the revised ‘T’ values for soil mapping units will help in planning of appropriate conservation measures for effective erosion control, sustainable crop production and improved watershed management in the Rajasthan State of western India.