Evaluation of On-Farm Irrigation Scheduling: Case Study of Drip Irrigated Potatoes in Southern Tunisia

摘要

Effective irrigation scheduling and the use of modern irrigation systems are two possible options to improve water use efficiency in arid regions. Drip irrigation is highly efficient, but is not always used properly. Over irrigation seems to be a common problem encountered with this system, due to inadequate scheduling. The potential of irrigation scheduling to improve yield and to save water is investigated in this study. A case study of drip irrigated potato grown on sandy soil in field trials is used. The growers method consisting of supplying a fixed amount of water is compared to the method of a daily compensation of calculated crop consumption (ETc =Kc*ET0) and the method of the Soil Water Balance (SWB) by compensating cumulated ETc. Well water with an ECi of 3.25 dSm 1 was used for irrigation over two cropping seasons. Yield, water supply and soil salinity were measured. Results show that in both seasons, fresh tuber yield was highest for the SWB scheduling technique, (40 and 30 tha 1) although no significant differences were observed with the daily irrigation method. The producer method not only caused significant reductions in yield but also resulted in using 20 to 25% more water and increased soil salinity. The highest water use efficiency was obtained with SWB: 11.77 and 9.13 kgm -3 of fresh potato, respectively for spring and autumn seasons i.e. about 64 and 86% more than that of the grower. The SWB method is recommended as a tool to use saline water for irrigation in arid Tunisia.