Setpoints for Potato Irrigation in Sandy Soils Using Real-Time, Continuous Monitoring of Soil-Water Content in Soil Profile

Abstract

ABSTRACT Adequate availability of water during the potato-growing season is critical for production of high yields of premium processing quality tubers. Real-time, continuous monitoring of soil water content in the soil profile can be used to optimize irrigation. In this study, capacitance probes were used for automated measurement of soil water content at 10, 30, 60, 90, and 120 cm depth in a Center Pivot irrigated potato (cv. Ranger Russet) field in a Quincy fine sand (mixed, mesic, Xeric Torripsamments). Depth integrated soil water content was calculated within the rooting depth (0–60 cm) and below the rooting depth (60–120 cm). Irrigation was scheduled to replenish either full evapotranspiration (ET), or 70% of ET (deficit irrigation). The soil water content at the 10 and 30 cm depth, as well as depth integrated soil water content in the 0–60 cm depth soil responded to each irrigation event. The “Full Point” and “Refill Point” for the soil within potato root zone (0–60 cm depth) were estimated to represent the maximum water holding capacity, and the soil water content at which irrigation is to be scheduled to avoid water stress, respectively. Depth integrated soil water content in the 0–60 cm-depth soil profile remained mostly above the Full Point during most of the growing season in the Full ET irrigation treatment, but remained within the Full Point and Refill Point for the deficit irrigation treatment.