Catchment basins were prepared within bunded fields from 1986 to 1988, with ratios of catchment area to cropped area of 1:1 or 2:1. Annual rainfall varied from 102 to 282 mm.
Run-off from the catchment basins increased water storage in the cropped areas by 55 and 43% of the rain falling on the catchments in the 1:1 and 2:1 treatments, respectively. Yields increased considerably on a cropped area basis by water harvesting, but not always sufficiently to compensate for the loss of cropped land. Averaged over all trials, yields from the 1:1 treatment were 95% of the control yields. Yields-in the 2:1 treatments were reduced by waterlogging damage.
The cost of catchment set-up was low compared with the reduced seed and ploughing costs in the water-harvesting treatments, resulting in 18 and 31% reductions in overall costs for the 1:1 and 2:1 treatments, respectively. Net benefits for the 1:1 treatment equalled or exceeded those of the control, but were 32% lower for the 2:1 treatment. Within-field water harvesting with a 1:1 crop: catchment ratio thus reduced risk by reducing investments in seed and animal draught power, whilst maintaining yields and net benefits, suggesting that it could be of considerable benefit to farmers in an environment with a high risk of crop failure. Catchment preparation on unused land adjacent to cropped land, and further research aimed at reducing waterlogging damage, could both lead to improvements in farmers' circumstances in upland Balochistan.