Day and night time sprinkler irrigated tomato: Irrigation performance and crop yield

The effect of day time vs. night time sprinkler irrigation on irrigation performance and tomato crop yield is assessed in this paper for the conditions of Tunisia. Field experiments were performed at the experimental station of Cherfech under two rectangular sprinkler spacings: 24 × 18 m and 18 × 18 m, denoted as plots M1 and M2, respectively. Results of performance evaluations indicate a significant effect of climatic and operation conditions on irrigation uniformity and wind drift and evaporation losses (WDEL). Experimental data were used to calibrate and validate a ballistic solid-set sprinkler irrigation simulation model and a soil-water-yield crop model. Based on the analysis of the main meteorological parameters during the irrigation season, the validated models were used to simulate night time irrigation (characterised by moderate wind speed and evaporative demand). Simulation results indicate that night time irrigation would greatly improve performance in comparison to day time operation: WDEL decreased from 24 to 7%, while irrigation uniformity increased from 50 to 64% in M1 and from 71 to 80% in M2. Simulated results showed that night time irrigation decreased relative yield losses (from 26 to 16% in M1 and from 11 to 3% in M2), as well as improving the spatial variability of crop yield (simulated yield CV in M2 decreased from 17 to 6%). Adoption of night irrigation in the study area will finally depend on local socioeconomic and water management constraints.