Determination of Technical Characters of Micro-Catchments Water Harvesting Systems for Rainfed Almond Trees

Water harvesting in agriculture mobilizes rainwater in a catchment area (usually non-productive) to benefit growing plants in a target area. This brings water available to the target area closer to crop water requirements so that economical agricultural production can be achieved, improving rainwater productivity. To investigate micro-catchment water harvesting (MCWH), a field experiment was conducted from 2000 to 2006 in East Azarbaijan in northern Iran using a split-split plot factorial design with five replications. Thetreatments comprised two MCWH patterns (small basins and semi-circular bunds); three catchments sizes of 25 m2 (5×5, R = 2 m), 49 m2 (7×7, R = 2.85 m) and 81 m2 (9×9, R = 3.7 m); three runoff area treatments (natural; cleaned and smoothed; cleaned, wetted and compacted); and two-infiltration areas (natural, soil mixed with polymer at 1 kg/tree) for two new almond varieties. Agronomic characteristics, product growth, threshold runoff and crop yield estimates were examined. The results were compared with farmed fields (traditional and irrigated) and showed that the tree survival rate was about 35%-55% for irrigated farmed fields and 100% for the MCWH site. The use of a polymer had no significant effect on water retention. Although a small basin (9×9) and runoff area that were compacted using a polymer gave better results for the survival, growth and productivity of almonds, a small basin (7×7) compacted without a polymer isrecommended based on the economic analysis. Threshold runoff was 2.5-3.5, 3.5-4.5 and 4.5-5.5 mm for the natural, cleaned and smoothed, and cleaned, wetted and compacted conditions, respectively. During the 2006 season, the fruit yield was estimated to be 3 kg/tree, totaling 612 kg/ha for the recommended treatment. For the farm fields, the optimal treatment combined required at least 1-2 irrigations during the summer.