The Rain Forest Research Institute (RFRI) here has launched a concerted effort to tackle the menace of jhum cultivation in the region. RFRI official Girindra Thakuria said that jhum cultivation resulted in serious depletion of the top soil and the cutting of trees on the hill sides led to an ecological imbalance in the area. "Rainfall usually decrease in the areas where the trees had been hacked and burnt to make way for agricultural crops,' Thakuria said. Moreover, washing away of the top layer of the soil resulted in siltation of rivers and subsequent floods,' he further said. Thakuria said that in the first year 146.6 tonne of soil, in the second year 2 tonne of soil was destroyed by erosion and rains in any given hillside cleared for jhum cultivation. "The decreasing quantity of top soil which was washed away was a clear indication of how much damage this is causing,' Thakuria. Jhum cultivation is a shifting method of agriculture in which a hillside having an incline of 60 to 70 per cent is cleared by cutting down and burning the trees and foliage to plant crops. In a few years when the soil fertility decrease, the people move on to a fresh patch or take up the practice in the place which they had abandoned a couple of years ago. In Asom, Jhum cultivation is practised in Karbi Anglong and the North Cachar Hill. According to statistics taken in 1996, 6,782 families were cultivating 92,518 hectare of land by this method, which was 2.16 per cent of the total cultivation. In the other north-eastern States, Mizoram had the highest per cent of land under jhum cultivation, that is 77.92 per cent, followed by Nagaland, 73.18 per cent, Arunachal Pradesh, 61.13 per cent and Meghalaya, 38 per cent. The Rain Forest Research Institute has undertaken awareness programmes in Karbi Anglong to initiate the people into the drawbacks of jhum farming and asked them to go in for terrace farming where the soil depletion is 20 per cent lesser. "By this method alternate horticulture crops like pineapple and other vegetables can be planted and in five years time and their earnings will increase to a great extent,' Thakuria said. "In bench terrace farming and contour bund system, grass or other useful vegetation are planted in the direction of the water flow to prevent the soil from being washed away,' Thakuria explained. "Our experiments have proved that the damage to the soil layer compared to the crop output is greatly decreased and subsequently the profits are greater,' Thakuria further said. "Moreover there is no need to go on shifting the area of cultivation in this method,' he added.