Optimal Drip Irrigation Frequency and Volume Mitigates Photosynthetic Impairment and Balances Yield–Resource Trade–Offs for Spring Maize in Arid Sandy Loam Soils

Abstract

Optimizing irrigation amount and frequency is critical for maize production in arid sandy loam soils, which are characterized by severe water scarcity and high leaching risks. This study aimed to determine the physiological and multi-objective synergistic responses of spring maize to different drip irrigation regimes in the sandy soil region of Southern Xinjiang and to identify the optimal water management strategy. A two-year field experiment evaluated four irrigation amounts (W1: 350 mm, W2: 500 mm, W3: 650 mm, W4: 800 mm) combined with three irrigation frequencies (F4: 4-day, F7: 7-day, F10: 10-day intervals). The results indicated that increasing irrigation amount and frequency generally improved canopy physiological performance (leaf area index, SPAD values, net photosynthetic rates, and photosystem II photochemical efficiency), though the response magnitudes varied among specific physiological parameters and irrigation levels. Grain yield increased with irrigation amount and was highest at 800 mm under F4 or F7 frequency; however, excessive water inputs led to reduced water productivity. Conversely, nutrient use efficiencies for nitrogen, phosphorus, and potassium exhibited a parabolic response, reaching their maxima under W3 (650 mm) and F7 (7-day interval). To reconcile the trade-offs between maximum productivity and resource conservation, the entropy weight method coupled with TOPSIS (EWM-TOPSIS) was applied. The results showed that grain yield and water productivity were the dominant indicators determining overall system efficacy, with the W3F7 treatment consistently achieving the highest relative closeness (over 76%) to the ideal solution in both years. While this optimal recommendation relies on the multi-criteria weighting framework of the EWM-TOPSIS model, integrating a 650 mm irrigation quota with a 7-day interval offers a practical agronomic strategy to balance yield, water productivity, and nutrient efficiency in arid agroecosystems.