Soil Erosion from Farming Lands in Tropical Islands of India

Abstract

Soil erosion from crop lands of tropical South Andaman district in Bay Islands of India was estimated using the Universal Soil Loss Equation. Using 38 years of rainfall, monthly and annual values of rainfall erosivity (R) were determined. Average monthly value of R was ranged from 1.48 to 132.67 metric ton.m.ha^-1hr^-1. It was observed that 103.77 thousand tonnes of soil were lost annually from the cultivable area of the district at the rate of 59.40 t ha^-1yr^-1. Under the single cropped land, green gram cultivated in kharif season contributes highest rate of soil loss (83.64 t ha^-1yr^-1) and ginger yields lowest rate of soil loss (22.17 t ha^-1yr^-1), whereas, for double cropped land, sweet potato-vegetable-fallow contributes lowest rate of soil loss (24.91 t ha^-1yr^-1) and green gram-vegetable-fallow yield highest rate of soil loss (79.09 t ha^-1yr^-1). Mono-cropped land contributed more soil loss due to upland farming situation, thin canopy, weak soil binding by crop roots, more erodibility and erosivity in the peak soil-eroding season and fallow state of crop lands. The average annual rate of soil loss in mono-crop land was estimated as 59.40 t ha^-1yr^-1 and that of double cropped land was estimated as 42.63 t ha^-1yr^-1. It is assessed that there would be a reduction of 28.23% soil loss if the mono cropped land is converted to double cropped land in the district.