Optimizing crop water productivity under center pivot sprinkler irrigation system
2012
Waris, M.
Center Pivot Sprinkler Irrigation System (CPSIS) is a high efficiency irrigation system which is being introduced in Pakistan. The crop productivity gaps can be minimized if water management under these systems carried out. Therefore, the study was conducted to determine crop water productivity at different water application depths and cost analysis to develop operational guide lines for CPSIS. Hysen-33, a commercial variety of sunflower was sown under the CPSIS on July 22nd, 2011. Irrigations were applied as 11 (100%), I2 (80%) and 13 (60%) of crop water requirement. Moisture content was monitored during the study period. Effective rainfall estimated in irrigation treatment I1 was 154 mm, in I2 172 mm, in I3 190 mm and in I4 244 mm. Total 110 mm irrigation water was applied under I1, 88 mm under I2 and 66 mm under I3. Sunflower yield under irrigation treatment I2 was 3151 kg per ha which was 20% more than I1 30% than 13 and 35% than I4. The water productivity under I1 was 0.96 kg m-3, 1.21 under I2, 0.89 under I3 and 0.82 under I4. Results suggest that crop yield can be maximized under deficit irrigation scheduling Economic analysis of 2.02 ha fix type (S-1), 29.14 ha (7.28 ha x 4 settings) (S-2) and 82.18 ha fix type (S-3) CPSIS and four cropping scenarios was carried out. The four cropping scenarios (each per crop year) were wheat-corn, canola-corn, canola-groundnut and wheat-sunflower. All cropping patterns gave negative values of net benefit under S-1. Wheat-sunflower cropping pattern gave maximum benefit under S-2 and S-3. Results show that small fix type CPSIS were found uneconomical and larger system may be adopted for maximum benefit.
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