Cost–benefit analysis of a regulated deficit-irrigated almond orchard under subsurface drip irrigation conditions in Southeastern Spain

A cost–benefit analysis was performed for a mature, commercial almond plantation [Prunus dulcis (Mill.) D.A. Webb] cv. Cartagenera in Southeastern Spain to determine the profitability of several regulated-deficit irrigation (RDI) strategies under subsurface drip irrigation conditions (SDI), compared to an irrigation regime covering 100% crop evapotranspiration (ETc). The plantation was subjected to three drip irrigation treatments for 4 years: T1 (control, surface drip irrigation)—irrigated at 100% ETc throughout the growth cycle, T2 (RDI treatment under SDI)—an irrigation strategy that provided 100% ETc except during the kernel-filling period, when only 20% ETc was provided and T3 (RDI treatment under SDI)—an irrigation strategy that provided 100% ETc except during the kernel-filling period (20% ETc) and post-harvest (50% ETc). A 45% water saving was achieved with strategy SDI T3, while almond production was reduced by only 17%, increasing water use efficiency compared to the control irrigation regime. SDI T3 had fixed overhead costs 9% higher than T1, however, the operating costs were 21% lower for SDI T3 compared to T1. This reduction in costs was basically due to the 45% saving in the cost of water and the corresponding saving in electricity. The break-even point was lower in SDI T3; each kilogram of almonds cost 0.03€ less to produce than in the control conditions. Related to this, the maximum price of water for obtaining profit 0 was 0.21€ m−3 for SDI T3 compared to 0.18€ m−3 for T1, indicating that higher water costs can be borne in SDI T3 (up to 0.03€ m−3 more expensive). Finally the profit/total costs ratio (used as an expression of the overall profitability of the orchard) indicated a greater profitability for the treatment SDI T3 compared to T1 (10.46 and 9.27%, respectively). The RDI strategy SDI T2 did not show economic indices or water use efficiency as much as those of SDI T3. From these results we conclude that RDI applied during kernel-filling and post-harvest under SDI conditions, and specifically the irrigation strategy SDI T3, may be considered economically appropriate in semiarid conditions in order to save water and improve water use efficiency.

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