Economical analysis of deficit irrigation management: A case study in an orange orchard

In the current experimental study, economic analysis of deficit irrigation was conducted for an orange orchard and results were evaluated based on the highests net income. This experiment was performed as a split plot in the form of a randomized complete block design with five replications in 2018. The main treatments were two types of irrigation management including variable irrigation interval and 4 days irrigation interval. Sub factor was 4 irrigation levels including 100%, 80%, 65% and 50% of soil readily available water (RAW). For economic evaluation, production, cost and income functions and optimum water use depths were calculated using English method. Results showed that irrigation water depth for maximum yield for two types of irrigation management was 148.3 and 186.5 mm, respectively. When land is limiting, the best irrigation water depths were 146.2 mm and 184.0 mm. When water is limiting, the irrigation water depths are 109.3 and 136.9 mm, respectively, which caused more than 16percent increase in net income per unit volume of water both two types of irrigation managements. With this amount of saved water , if land is not limited, the cultivated area can be increased up to 36% and 36%. Results showed that the optimum irrigation water management (in unlimited conditions) is 4 days irrigation interval and 80%RAW irrigation depth. For this situation, the yield was 55 ton/ha. The net income for this case is more than 483 million Rials per hectare and B/C equals to 1.78. The highest net income (for no land limitation and irrigation depth equivalent to full irrigation), is irrigation as large as Ww (water limitation conditions) that net income for the without and 4 days irrigation interval are more than 476 and 611 million Rials, respectively. This case generates the most net income per unit volume of used water. Results showed that in both unlimited condition and in water limitation condition, having an irrigation schedule and also applying deficit irrigation has a positive effect on the gardener's income that for deficit irrigation in unlimited condition 1492 and in water limitation condition 1369 m3/ha water is needed.