Investigation and Comparison of Different Irrigation Scheduling Methods in an Orange Orchard in a Semi-arid Region

Numerous techniques exist for the scheduling of irrigation. Nevertheless, there has been insufficient focus on the comparative analysis of these techniques across different dimensions. This study endeavors to investigate and evaluate several irrigation scheduling devices and methodologies, considering factors such as irrigation water usage, water productivity, fruit yield and quality, economic advantages, and the priorities of farmers. The current investigation aimed to fill this gap by conducting a comprehensive analysis of eight irrigation scheduling methods applied in an orange orchard, comparing them with the conventional method. A randomized complete block design with nine treatments and three replications was utilized, and the resulting data underwent Duncan's test. Measurements were taken over 2 years to determine the annual irrigation water, yield, water productivity, and qualitative characteristics of the orange fruit. Additionally, a thorough evaluation was carried out to assess the net benefit of each irrigation scheduling method in relation to the conventional approach. The priority of treatments was evaluated using the Analytic Hierarchy Process (AHP). Results from this study showed that none of the irrigation scheduling methods led to a reduction in both the quantity and quality of yield compared to the conventional method. The minimum and maximum volumes of irrigation water utilized for irrigation planning, employing a single gypsum block and two tensiometers, were recorded at 5960 and 9440 m(3)/ha, respectively. In contrast, the irrigation water applied under the farmer's conventional management practices amounted to 10,440 m(3)/ha. Therefore, the average irrigation water decreased by 9 to 57% compared to conventional irrigation. Irrigation water productivity in the farmer-managed treatment was measured at 1.61 kg/m(3), while in the irrigation scheduling treatments, it ranged from 2.01 to 3.89 kg/m(3). The higher value was observed in the treatment utilizing two soil moisture meter sensors, whereas the lower value was recorded in the treatment employing a single soil moisture meter sensor. Irrigation water productivity in the various irrigation scheduling treatments exhibited an increase ranging from 25 to 141% when compared to the productivity observed in farmer-managed treatments. It is crucial to highlight that the net benefit of each irrigation scheduling method was greatly influenced by factors like water prices, fruit prices, and labor costs. The irrigation scheduling treatments that employed predetermined water requirements (Penman-Monteith) and utilized two soil moisture sensors exhibited the most significant disparities in economic benefits when compared to the farmer-managed treatment, recording values of 5325 and 817 dollars per hectare annually, respectively. Ultimately, considering various technical and economic aspects using AHP, the Penman-Monteith method, canopy temperature measurement, and soil moisture measurement using a single sensor to determine the irrigation start time were identified as the most favorable methods for irrigation scheduling.