ASSESSMENT OF PERMISSIBLE SOIL LOSS IN INDIA EMPLOYING A QUANTATIVE BIO- PHYSICAL METHOD

Abstract

SOIL DEGRADATION IN ALL ITS NEFARIOUS FORMS HAS SERIOUS REPERCUSSIONS ON CROP AND BIOMASS PRODUCTIVITY . ASSESSMENT OF SOIL LOSS TOLERANCE LIMITS ( SLTLs) ( PERMISSIBLE SOIL LOSS) SERVES AS A TOOL TO GAUGE THE POTENTIAL EROSION RISK IN A GIVEN AREA WITH REGARD TO LONG- TERM SUSTAINABILITY. IN THIS COMMUNICATION, SLTLs IN DIFFERENT STATES IN INDIA AND AT THE NATIONAL LEVEL HAVE QUANTITATIVELY ESTIMATED BY EMPLOYING A BIO- PHYSICAL MODEL BASED UPON INTEGRATION OF RELEVANT ATTRIBUTES. THE ANALYSIS HAS INDICATED THAT SOIL LOSS TOLERANCE OR T- VALUES VARIES FROM 2.5 TO 12.5 Mg ha-1 yr-1 DEPENDING UPON SOIL QUALITY GOVERNING SOIL RESISTIBILITY TO EROSION AND DEPTH AT A PARTICULAR LOCATION. ABOUT 57% OF THE AREA IN THE COUNTRY HAS PERMISSIBLE SOIL LOSS OF LESS THAN 10.0 Mg ha-1 yr-1 , WHICH NEEDS TO BE TREATED WITH APPROPRIATE CONSERVATION MEASURES. HIGHEST PRIORITY NEEDS TO BE ACCORDED TO ABOUT 7.5% AREA WHERE THE T- VALUE IS ONLY 2.5 Mg ha-1 yr-1 DUE TO SOIL QUALITY CONSTRAINTS. THE METHODOLOGY AND FRAMEWORK DEVELOPED FOR ESTIMATING T- VALUES HAS THE POTENTIAL TO BE APPLIED IN DIFFERENT REGIONS OR COUNTRIES OF THE WORLD. THE RELATIVE EFFICACY OF THE PRESENT METHOD WAS TESTED WITH PRODUCTIVITY INDEX- BASED APPROACH. CASE STUDY EVIDENCES IN DIFFERENT WATERSHEDS REVEALED THAT SOIL PRODUCTIVITY CAN BE MAINTAINED AT SUSTAINABLE LEVELS BY BRINGING THE EROSION RATE WITHIN TOLERANCE LIMIT.