Optimizing water-nitrogen management enhances productivity for peanut (Arachis hypogaea L.) with drip-irrigated under mulched in Northwest of China

Water scarcity and excessive fertilizer use have emerged as pressing issues, threatening sustainable agricultural development. To mitigate these challenges, it is crucial to explore irrigation and fertilization systems that can synergistically enhance crop yields while improving the efficiency of water and fertilizer use. A two-year field experiment was conducted to investigate the effects of water and nitrogen management on peanut growth and yield, with the goal of optimizing water and nitrogen scheduling based on AquaCrop modeling. The experiment consisted of three irrigation levels (I1: severe water deficit, I2: mild water deficit, I3: full irrigation), two nitrogen application levels (F1: half nitrogen application, F2: conventional nitrogen application), and a control treatment (CK) without nitrogen application. The results demonstrated that, under the condition of this experiment, the optimal irrigation and nitrogen application combinations were I3F2 in 2022 and I2F1 in 2023. Compared with the CK treatment, these combinations increased pod yield by 25.13–55.88 %, kernel oil content by 1.27–3.56 %, and water productivity by 26.74–44.44 %. The AquaCrop model showed excellent performance in simulating key parameters, including soil water storage (NRMSE = 9.63–25.06 %, d = 0.54–0.91), canopy cover (NRMSE = 5.52–22.74 %, d = 0.78–0.99), aboveground biomass (NRMSE = 6.79–26.02 %, d = 0.97–0.99), water consumption (NRMSE = 5.17 %, d = 0.91), water productivity (NRMSE = 11.56 %, d = 0.53), and yield (NRMSE = 9.67 %, d = 0.87,). After comprehensively evaluating 130 scenarios using the Entropy Weight Method-Technique for Order Preference by Similarity to an Ideal Solution method, the optimal irrigation and nitrogen application regime for peanut production under drip irrigation with plastic mulch was determined as follows: irrigation of 45 mm from sowing to emergence, 7-day intervals with 40.5 mm each during the flowering-pegging and pod-setting stages, and 10-day intervals with 40.5 mm per irrigation during the pod-filling stage, along with the application of 100 kg·ha−1 nitrogen. This optimized regime effectively balances water and nitrogen use to maximize peanut yield and productivity while ensuring sustainable agricultural practices.