Evaluation of variable rate irrigation management in forage crops: Saving water and increasing water productivity
Maona Li, Yunling Wang, Hui Guo, Feng Ding, Haijun Yan
Abstract
Variable rate irrigation (VRI) technology matching appropriate irrigation applications to specific areas could contribute to water savings compared to uniform rate irrigation (URI) within at the field scale. A three-year field study (2019–2021) was carried out at an experimental station of China Agricultural University in Zhuozhou, Hebei Province, China, to compare VRI with URI in sudangrass (Sorghum sudanense) and alfalfa (Medicago sativa L.). The field was divided into three management zones (MZs) in accordance with the soil apparent electrical conductivity (ECa). and each MZ was further subdivided into two subzones to apply VRI and URI. The feasibility of considering the ECa as an MZ delineation approach was supported by the fact that significant differences in yields existed among MZs in each cutting and annual of sudangrass. Sudangrass obtained higher coefficients of variation (CVs) than alfalfa in terms of the yields, crop water use (ETa), water use efficiency (WUE) and irrigation water use efficiency (IWUE), with values ranging from 7.64% to 21.25% and from 1.13% to 7.63% for sudangrass and alfalfa, respectively. No significant differences existed between the VRI and URI with regards to the yield, WUE or IWUE in the three years of study. Compared to URI, VRI had a better water-conservation performance, especially in the rainy season, with average reductions of 22.2% and 12.6% (only in 2020) for sudangrass and alfalfa, respectively. These findings demonstrated VRI’s advantage in saving water and increasing water productivity in two forages and that VRI could be applied in regions with limited water supplies such as the North China Plain.