Consumptive Water Use of Pecans in Southern Arizona

The production of pecans [Carya Illinoinensis (Wangeh.) K. Koch] in Arizona has increased substantially in recent years (Parsons, 2017; Murphree, 2020). A recent economic impact study indicates more than 30,000 acres of pecans are now established in Arizona, nearly double the acreage reported in 2013 (Duval et al., 2019). The majority of Arizona pecan orchards are located in Southern Arizona with nearly all new production located in Cochise County where groundwater levels are declining due to overdraft of local aquifers (ADWR, 2018). Pecans are considered a high- water use crop due in large part to an extended growing season that begins in late March and continues through mid-November at most locations. Aside from one study that evaluated the feasibility of using infrared thermometry to schedule irrigation events (Garrot et al., 1993), there are no published data sets addressing the consumptive water use (CU) of Arizona pecans. The purpose of this bulletin is to summarize the results of a three-year study conducted in southern Arizona to 1) quantify the CU of southern Arizona pecans and 2) provide crop coefficients (Kc) and CU curves to facilitate improved irrigation management of pecans.