Evaluation and Determination of Water Productivity of Alfalfa in the Darbasti Irrigation System with Different Sprinkler Placement Patterns

The Water Productivity (WP) of the Darbasti Irrigation System (DIS) was evaluated in Alfalfa cultivation in the Markazi Province. The evaluation included three patterns of sprinkler placement: 8x8 meter (SS-88), 8x10 meter (SS-810), and 8x12 meter (SS-812). The Distribution Uniformity (DU), Coefficient of Uniformity (CU), Application Efficiency of Low Quarter (AELQ), and WP were determined in the years 2018 and 2019, after the third (HA-3), fourth (HA-4), and fifth (HA-5) yield harvests. The results showed that the average CU in the SS-88 pattern was 84.76% in the first year and 86.34% in the second year. This pattern had the highest CU compared to the other two patterns. The DU in SS-88, SS-810, and SS-812 patterns in the first and second year was 77.3%, 79.31%, and 75.38%, 77.66%, and 70.11%, 70.88%, respectively. These results indicate very good, good, and relatively good performance in each of the patterns, respectively. Moreover, there was a significant difference at the one percent level in the AELQ between the first and second year for all three patterns. The results showed a significant difference at the level of one percent between the SS-812 model and the other two models. The WP of alfalfa was 1.84 kg/m3, 1.87 kg/m3, and 2.28 kg/m3 for SS-88, SS-810, and SS-812 patterns, respectively, in the first year. In the second year, this index was 2.43 kg/m3, 2.3 kg/m3, and 2.4 kg/m3 for the same patterns, respectively. Generally, the SS-810 pattern of sprinkler placement is a suitable choice based on performance indicators.