ABSTRACT LISS Linear Imaging Self Scanner LS Topographic factor LU/LC Land use/ land cover LUP Land use planning M Million m Meter m3 Cubic meter Mha Million hectare MJ Mega Joule mm Millimetre mm/hr Millimetre per hour N North NBSS National Bureau of Soil Survey No. Number OC Organic carbon OM Organic matter P Conservation practice factor R Rainfall erosivity factor RS Remote sensing S Slope steepness factor SCS Soil Conservation Service SOI Survey of India SPAW Soil-Plant-Air-Water SRTM Satellite Radar Topography Mission T Tonne USDA United States Department of Agriculture USLE Universal soil loss equation viz. Namely yr Year "SOIL EROSION AND CROP PRODUCTIVITY MODEL FOR RATNAGIRI DISTRICT" By Sanjani Sunil Salunkhe Department of Soil and Water Conservation Engineering, College of Agriculture Engineering and Technology, Dr. Balasaheb Sawant Konkan Krishi Vidyapeeth, Dapoli Dist- Ratnagiri, Maharashtra 2017 Research Guide : Prof. dilip MAHALE Department : Soil and Water Conservation Engineering Soil degradation has reached alarming proportions in many parts of the world, especially in the tropics and sub-tropics because of its uneconomic overexploitation. Also soil degradation is one of the most critical environmental hazards of recent times. A large area suffers from soil erosion, which in turn, reduces productivity. For protection of land and to meet the increasing demand of food, it is necessary to understand soil formation and erosion process. This kind of study is very essential in Konkan region of Maharashtra due to extreme weather conditions and huge loss of soil through runoff. Therefore, there is need to study estimation of actual soil loss and tolerable soil loss which helps to convert topsoil loss into productivity loss. Ratnagiri district of Konkan is located between 15040' and 18°5' N latitude and 7305' and 73055' E longitude. The total geographical area of Ratnagiri district is 8,461 sq. km. with average annual rainfall of 3,591mm, which comprises of nine tehsils. Universal Soil Loss Equation (USLE) model was used to predict soil loss from the Ratnagiri district of Maharashtra, India. Remote Sensing (RS) and Geographic Information System (GIS) techniques were applied to prepare various layers of USLE parameters which interactively estimate soil erosion from Ratnagiri district. Average annual soil loss was estimated with the help of average annual R factor obtained from 28 years rainfall data, K, LS, C and P. The average annual erosivity of Ratnagiri district was 10,195.48 MJ-mm/ha-hr-yr. Soil erodibility factor for different villages of Ratnagiri district were found in the range of 0.0346 to 0.0636 t-ha-hr/ha-MJ-mm. The values of LS factor for study area was found in the range of 1.953 to 4.393. Crop management factor (C) values for study area were ranging from 0.024 to 0.12. Conservation practice factor was considered 1 before recommendation of soil and water conservation measures and used to estimate soil loss. Average annual soil loss from the Ratnagiri district was 43.61 t/ha/yr before recommendation of soil and water conservation measures. It was observed that about 57.62 % area was under severe erosion class, 24.24% area was under very severe erosion class and 14.17% area was under extremely severe erosion class of Ratnagiri district without soil and water conservation treatments. Thus, more than 80% of area from Ratnagiri district comes under severe (20-40 t/ha/yr) to extremely severe (>80 t/ha/yr) erosion classes. This proves the high need of soil and water conservation measures in the watershed for the sustainable management of natural resources. Tolerable soil loss of Ratnagiri district was estimated based on imperial relations with the help of bulk density, depth of soil and other data. Estimated average tolerable soil loss and conservation practice factor (P) values for Ratnagiri district are 9.45 t/ha/yr (for moderately deep soil) and 0.21, respectively. Average annual soil loss from study area would reduce to 9.31 t/ha/yr after adoption of recommended soil and water conservation measures and following 7 years of crop cycle. It was observed that about 58.32% area is expected to come under moderate erosion class, 26.19% area under slight erosion class, 13.07% area under severe erosion class, 2.40% area under moderately severe erosion class, and 0.01% area under very severe erosion class after adoption of soil and water conservation measures. Thus, soil erosion and crop productivity model can be effectively used for planning of soil and water conservation measures in Ratnagiri district.