Journal of Environmental Biology

Geospatial assessment of water induced soil and nutrient erosion in Pabho watershed of Assam, India using USLE model

S. Borgohain¹, B. Deka²*, M. Dutta¹, R.K. Thakuria² and D.K. Patgiri¹ 

¹Department of Soil Science, Assam Agricultural University, Jorhat-785 013, India

²AICRP on Irrigation Water Management, Assam Agricultural University, Jorhat-785 013, India

*Corresponding Author Email : drbipuldeka@gmail.com

Received: 13.06.2020                                                                   Revised: 15.11.2020                                                    Accepted: 15.12.2020

Abstract

Aim: To assess the water induced soil and nutrient erosion status as well as to suggest conservation measures for Pabho watershed located in the northern Brahmaputra plains of Assam.

Methodology: A study was conducted to generate information about the annual soil loss of Pabho watershed using Universal Soil Loss Equation and ARC GIS. Soil loss was estimated by multiplying five parameters of USLE i.e. R (Rainfall erosivity factor), K (Soil erodibility factor), LS (Topographic factor), C (Crop management factor) and P (Conservation support factor).Nutrient erosion as well as its monetary values were also estimated by taking count of fertile soil loss.

Results: The rainfall erosivity factor (R) for watershed area was 895.08 MJ ha” 1 mm” 1 and the soil erodibility factor (K) ranged between 0.033 and 0.118.The LS value varied from 0.36 (flood plain) to 1.72 (piedmont plain). The estimated soil loss in the study area varied from 0.38 t ha^-1 yr^-1 to 45.97 t ha^-1 yr^-1 with a mean value of 10.80 t ha^-1 yr^-1. Annual soil loss was highest in the piedmont plain and lowest in the flood plain. The amount of eroded nutrients from the agricultural land of watershed area was computed to be 7149.39 kg N, 1050.18 kg P₂O₅, 2582.41 kg K₂O and 0.51 ton of organic C per year. The total monetary value of eroded nutrients was estimated to be around Rs. 52,92,537per year.      

Interpretation: The study demonstrates the use of USLE as a powerful approach for the assessment of soil erosion and identifying the erosion prone areas. Based on the assessment of erosion soil, loss soil conservation management practices like vegetative bunds, mulching, reduced tillage, intercropping are suggested for piedmont plain soils.       

Key words: Nutrient erosion, Soil conservation, Soil loss, USLE model, Watershed

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