FIELD EVALUATION OF GRAVITY-FED SURFACE DRIP IRRIGATION SYSTEMS IN A SLOPED GREENHOUSE

This study was conducted to evaluate the water application uniformity for a surface drip irrigation system, considering water quality and field slope. The uniformity parameters like average emitter discharge qa , relative emitter discharge R, standard deviation of emitter flowrate Sq coefficient of variation of emitter flow Cv, statistical uniformity Us, emission uniformity EU and Uniformity coefficient Uc were determined for a gravity-fed surface drip irrigation system installed on a slanted land (5.34 % slope). The discharge recorded along the lateral length was 0.74 l/h and 0.69 l/h for section 1 and 2 respectively. These were higher than the manufacturers specification of 0.5 to 0.6 l/h. The values of Us, EU and Uc were quite high for the two sections. The Cv, Us, EU and Uc obtained were 0.14, 86 ± 3%, 90% and 93% respectively in Section-1 and 0.15, 85 ± 3%, 83% and 87% respectively in Section-2. The overall performance description for Cv, Us, EU and Uc were very good, good, excellent and excellent respectively for Section-1 and very good, good, good and good respectively in Section-2. The study also revealed that the mean emitter discharge for section 1 and section 2 were not significantly different at confidence level of 95% (P < 0.05). What affected the emitter discharge was not the water quality at the study sit