The data source of zoning is a key factor affecting the investment cost and application effect of variable rate irrigation (VRI) technology. To evaluate the water-saving performance and yield responses to static versus dynamic zoning VRI management strategies, a field experiment was conducted during the 2023–2024 winter wheat growing seasons under sprinkler irrigation in Ningjin County, Hebei Province, China. Three VRI treatments were evaluated: (i) static zonal VRI based on soil available water holding capacity (T1), (ii) dynamic zonal VRI based on normalized relative canopy temperature (NRCT) (T2), and (iii) dynamic zonal VRI integrating NRCT with vegetation indice calculated with multispectral band data (T3). Farmer-managed irrigation and fertilization practices were used as the control (CK). The effects of these strategies on crop growth, grain yield, and water use efficiency (WUE) were assessed under sector-based irrigation zones. In 2023, all VRI treatments maintained grain yield statistically similar to CK while reducing irrigation input by 25.2% on average. In 2024, following optimized fertilization amount and topdressing time, VRI significantly increased yield by up to 9.0%, saved 30.9% irrigation water on average, and improved WUE by 26.4% on average. Differences in grain yield and WUE among the three VRI treatments were still not statistically significant ( P > 0.05). Our results demonstrated that static VRI, single-source dynamic VRI and dual-source dynamic VRI management exhibited no significant differences in water-saving performance and grain yield, and VRI combining with optimized fertigation technology supplied method for simultaneously improvement of water saving and yield.
Zhang et al. (Sat,) studied this question.