Soil water extraction patterns and water use efficiency of irrigated sugarbeet under full and limited irrigation in an arid climate

The effects of full and limited irrigation sugarbeet production practices on soil water extraction and evapotranspiration water use efficiency were investigated in 2015, 2016, and 2017 near Kimberly, Idaho. Four irrigation regimes (fully irrigated (FIT), 75% FIT, 50% FIT and 25% FIT) were studied in 2015 and 2017 and three irrigation regimes (fully irrigated, 60% FIT, 30% FIT and rainfed) were studied in 2016. Soil water was extracted from all layers of the 2.25 m soil profile and the pattern of extraction was impacted by irrigation regime. In general, net soil water depleted from the 2.25 m soil profile between emergence and harvest and seasonal average soil water extraction decreased with depth and irrigation amount. For all irrigation treatments and all study years, 70 to 90% of soil water extraction was from the 0 to 1.2 m soil profile and 4 to 10% of soil water extraction was from the 1.8 to 2.25 m soil profile. Water use efficiency increased under limited irrigation. Root yield water use efficiency was greatest for the 50% FIT, 60% FIT and 75% FIT treatments in 2015, 2016, and 2017, respectively. Estimated recoverable sucrose water use efficiency was greatest for the 50% FIT, 60% FIT, and 50% FIT treatments in 2015, 2016, and 2017, respectively. Root yield water use efficiency was greater and estimated recoverable sugar water use efficiency was equal or greater than reported in previous reported studies