MART-AZR Project Research Report 40: Catchment Basin Water Harvesting as a Means of Improving the Productivity of Rainfed Land in Upland Baluchistan

Abstract

Small catchment basins of different sizes were prepared within bunded fields on gently sloping silty valley bottom soils in upland Balochistan from 1985 to 1988. The ratios of catchment area to cropped area were 1:1 or 2:1. Seasonal rainfalls were 282, 102 and 239 mm in 1986/87, 1987/88 and 1988/89 seasons, respectively., Increased water storage in the cropped areas of 55%. and 43%. of the rain falling on the catchments were observed in the 1:1 and 2:1 treatment. Yields were considerably increased on a cropped area basis by the water harvesting treatments, but not always sufficient to compensate for the loss of cropped land. The 2:1 treatment suffered from water-logging damage, even in the low rainfall year. The cost of catchment set-up was low compared to the reduced seed and ploughing costs in the water harvesting treatments, resulting in 21 and 34% reductions in overall costs for the 1:1 and 2:1 treatments. Net benefits were 33%. higher than the control for the 1:1 treatment overall, but 27%. lower for the 2:1 treatment. Labour inputs were less for the water harvesting treatments, with the result that returns to labour were more than doubled by water harvesting. Within-field water harvesting with a 1:1 crop: catchment ratio thus reduced risk by reducing investments in seed, animal draft and labour, whilst maintaining yields, suggesting that it could be of considerable benefit to farmers in an environment with a high risk of crop failure. The potential for forming catchments on adjacent unused land, and further research aimed at reducing water-logging damage, could both lead to further improvements in farmer circumstances in upland Balochistan.