Technical and economic study of irrigation scheduling devices on corn water productivity in a semi-arid region

It is essential to consider water allocation control and on-farm irrigation scheduling to increase water productivity in agriculture. There are several devices used for irrigation scheduling, however the best device with the most priority is not identified yet. In the present study, the effect of using several irrigation scheduling devices on increasing water productivity in a corn field was investigated. The devices were classified technically and economically using analytic hierarchy process. The experimental farm was located in a semi-arid region in Iran, which was managed by a farmer and irrigated with drip irrigation system. Six techniques for irrigation scheduling were studied including Penman-Monteith model (T2), infrared thermometer (T3), soil moisture meter (T4), tensiometer (T5), and gypsum block (T6). The irrigation scheduling treatments were compared with the conventional treatment adopted by the farmer (T1). Economic analysis was performed. The ease of use of the devices was also evaluated. Results showed for the irrigation scheduling treatments of T3 to T6, applied irrigation water was reduced by 11 to 26% compared to T1. The corn yield in irrigation scheduling treatments was not reduced significantly compared to T1. As a result, water productivity increased by 35% from 2.0 to 2.7 kg/m3. The best irrigation scheduling device in terms of water productivity was gypsum block. In regard to affordability and ease of use by farmers, the Penman-Monteith model had more priority. Considering all assessment criteria, tensiometer (T5) was given the first priority. The infrared thermometer (T3) and Penman-Monteith model (T2) were identified as the next priorities.