A Reduced Early Season Irrigation Schedule for Southeastern Pecan Production

Pecan are known to be a high water use crop; however most pecan irrigation research has been conducted in the western pecan growing regions of the United States. The pecan-growing region of Georgia receives significantly more rainfall than the pecan growing regions of the desert Southwest. Yet, because the timing of rainfall does not usually coincide with the period of greatest water demand by the pecan tree, irrigation remains necessary in the Southeastern U.S. for consistent production of high-quality pecans. Very little research based information is available regarding the true water requirements of pecan in the Southeastern U.S. With increasing agricultural water use, a growing population, and current groundwater levels at record lows, irrigation efficiency in the region is necessary for sustainability. A study was developed in 2012 to test the validity of a proposed reduced-rate early season irrigation schedule for Southeastern pecan production utilizing micro-sprinkler irrigation. Three treatments were evaluated; 1) current recommended irrigation schedule; 2) reduced rate schedule; and 3) non-irrigated control. Treatments were arranged in a randomized block design with each treatment replicated five times in single-tree plots. Water stress was measured weekly by stem water potential using a pump-up pressure chamber. Soil moisture was measured at the same time using a Field Scout TDR 300 Soil Moisture Meter. Shoot length, pecan yield, nut weight, and percent kernel were measured annualy. Water stress on pecan occurred at about 113 psi using the pressure chamber to measure stem water potential. Regression analysis suggests that irrigation scheduling for mature pecan trees may be needed when volumetric water content reaches 10% to 11% on Tifton loamy sand. The reduced rate irrigation schedule provided a 38% reduction in irrigation water use with no significant effect on pecan tree water stress, yield, or quality.

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