Potatoes irrigated at 80% and 100% replenishment of soil water depletion to field capacity resulted in statistically similar tuber yields and irrigation water productivity.
In the drier growing season, irrigation scheduling using sensor feedback resulted in fewer irrigations compared with the manual-control method.
In the wetter growing season, irrigation scheduling using sensor feedback resulted in similar or better tuber yields compared with the manual-control method.
Abstract. Few studies have investigated yield and crop water productivity of plant and soil water sensing feedback systems for site-specific irrigation management of a potato crop. In this two-year study (2018 and 2019), the irrigation scheduling supervisory control and data acquisition (ISSCADA) system developed by scientists at the USDA-ARS Conservation and Production Research Laboratory in Bushland, Texas, was used to manage a potato crop at three irrigation levels. The ISSCADA system used two different irrigation scheduling methods: (1) plant feedback and (2) a hybrid method that combines plant feedback with soil water sensing with a soil water depletion (SWD) threshold initially set at 50% and reduced to 35% in the second year. Tuber yield, crop water productivity (CWP), and irrigation water productivity (IWP) resulting from the two ISSCADA irrigation scheduling methods were compared with a manual-control method based on weekly neutron probe readings. The irrigation levels were 100%, 80%, and 60% (I100, I80, and I60) of full and were accomplished by either replenishment of SWD to field capacity or by the equivalent plant feedback or SWD thresholds of the ISSCADA system. In the second study year, the SWD threshold was reduced to 35%. Cumulative irrigation amounts for the ISSCADA treatment methods were significantly less compared with the manual-control method in the I100 levels for both years. This resulted in significantly smaller tuber yields and CWP in the first year of the study, a hot dry growing season. In the second year of the study, tuber yields and CWP were similar between irrigation scheduling methods, and IWP was significantly greater for the ISSCADA-plant feedback method. Considering the effect of irrigation treatment, the tuber yields, CWP, and IWP between the I100 and I80 levels were similar in both years, resulting in an average savings of 85 mm at the I80 level. Future studies are needed to investigate if the change in the SWD threshold could enable the ISSCADA-hybrid system to adjust to variable climatic conditions and successfully irrigate potatoes in this region. Keywords: Center pivot, Dynamic prescription maps, Plant feedback, Site-specific variable-rate irrigation, Soil water sensing feedback, Wireless sensor networks