ADJUSTED T VALUES FOR CONSERVATION PLANNING IN NORTHWEST HIMALAYAS OF INDIA

Abstract

TOLERANCE SOIL LOSS(T) IS DEFINED AS THE MAXIMUM RATE OF ANNUAL SOIL EROSION THAT ECONOMICALLY AND INDEFINITELY WILL CONTINUE TO SUSTAIN A HIGH LEVEL OF CROP PRODUCTIVITY . CURRENTLY A T VALUE IS ASSIGNED TO A SOIL BASED ON ITS CURRENT FUNCTIONAL STATE AND STRUCTURAL INTEGRITY . HOWEVER, IN INDIA A DEFAULT T VALUE OF 11.2 Mg ha-1 yr-1 (5.0 t ac-1 yr-1) IS BEING FOLLOWED. OUR OBJECTIVE IS TO PROVIDE ADJUSTED T VALUES OF INDIA'S NORTHWEST HIMALAYAN REGION BY INCORPORATING BULK DENSITY, WATER STABLE AGGREGATE MEASUREMENTS , INFILTRATION RATE , SOIL CARBON AND FERTILITY STATUS INTO ASSESSMENT. A QUANTITATIVE MODEL WAS USED TO SUM UP OVERALL SOIL PERFORMANCE TO DEFINE THE CURRENT STATE OF SOIL RESOURCE. SCALING FUNCTIONS WERE USED TO CONVERT SOIL PARAMETERS TO A 0 TO 1 SCALE. THE NORMALISED VALUES WERE THEN MULTIPLIED BY APROPRIATE WEIGHTING FACTORS BASED ON A RELATIVE IMPORTANCE AND SENSITIVITY ANALYSIS OF EACH INDICATOR. A CATEGORIAL RANKING OF SOIL 1,2, 3 WAS GIVEN TO SOIL GROUP BASED ON THE OVERALL ASSESSMENT. A GENERAL GUIDELINE DEVELOPED BY THE USDA . NATURAL RESOURCE CONSERVATION SERVICE WAS FOLLOWED TO CALCULATE SOIL LOSS TOLERANCE FOR EACH SOIL GROUP USING EFFECTIVE SOIL DEPTH. ADJUSTED T VALUES FOR THE AREA RANGED BETWEEN 5.0 AND 12.5 mg ha-1 yr-1 ( 2.2 AND 5.6 T AC-1YR-1) COMPARED TO 11.2 MG HA-YR-1 (5.0 T AC-1YR-1). USE OF THE ADJUSTED T VALUES WILL IMPROVE CONSERVATION PLANNING, HELP MEET EROSION CONTROL REGULATIONS FOR DEVELOPMENT OF SUSTAINABLE FARM OPERATIONS , AND IMPROVE WATERSHED MANAGEMENT IN THIS PORTION OF INDIA.