Optimizing Irrigation Regimes for Peanuts in Water-Scarce Regions: A Case Study in Western Liaoning, China

Scientific irrigation scheduling is crucial for conserving agricultural water resources, as excessive irrigation diminishes crop yield and imprecise water application can equally reduce water use efficiency (WUE). In Western Liaoning Province, China, where water scarcity is critical, traditional irrigation regimes are commonly used for peanut cultivation, with local farmers applying water without considering actual crop water demands, thereby reducing water efficiency and yield. In this study, field experiments on peanuts were conducted from May to October during 2021 and 2022 in Heishan County, Western Liaoning Province, China. Four irrigation regime treatments for micro-sprinkler irrigation, with different lower limits of soil water content, were applied: T1 (55% field capacity), T2 (65% field capacity), T3 (75% field capacity), and T4 (85% field capacity). The plant height, stem thickness, root length, dry matter weight, yield, WUE, and net return were measured. Different irrigation regimes had significant effects on peanut growth. The yield was highest in the T3 treatment in 2021 at 5574 kg·hm−2. Moderate irrigation could improve the yield, but it was difficult to simultaneously achieve a high WUE. The WUE of the T3 treatment was 5% lower than that of the T2 treatment in 2022, where the WUE was the highest at 1.62 kg·m−3. The highest net return was observed in the T3 treatment at 27,307 yuan·hm−2. The T3 treatment, with the highest similarity degree of 0.83 as determined with the entropy value and TOPSIS method, was evaluated as the optimal irrigation regime. This regime not only exhibited a favorable balance of water use efficiency and yield but also maximized economic benefits, making it a recommendable practice for local peanut irrigation.