Synergistic effects of row configuration and nitrogen level on water utilization and system productivity in maize/soybean strip intercropping system on the Loess Plateau of China

Intercropping is widely recognized as an effective strategy for enhancing resource use efficiency and promoting agricultural sustainability. However, the synergistic effects of row configuration and nitrogen application on system productivity and resource use efficiency in maize/soybean intercropping system remain poorly understood. A two-year field experiment (2022–2023) was conducted to evaluate plant growth, grain yield, water, nitrogen and land use efficiencies, as well as economic profits of maize/soybean strip intercropping system in response to various row configurations (M2S2: two maize rows with two soybean rows, M2S4: two maize rows with four soybean rows, M4S4: four maize rows with four soybean rows, MM: maize monocropping, S: soybean monocropping) and maize nitrogen application levels (N0: 0 kg·ha −1 , N1: 150 kg·ha −1 , N2: 250 kg·ha −1 ). The results showed that M2S4 configuration effectively alleviated the shading stress on soybean and optimized canopy structure, while N1 enhanced biomass accumulation, stem strength, and lodging resistance, together maximizing intercropping advantages. Across all intercropping treatments, system yields increased by 7.16 %–23.36 % compared with monocropping. The highest yield was obtained under N1 + M2S2 (7647.66 kg·ha −1 ) in 2022, with N1 + M2S4 producing a slightly lower yield (7274.50 kg·ha −1 ), whereas N1 + M2S4 achieved the highest system yield in 2023 (7704.24 kg·ha −1 ). Although intercropping generally reduced water productivity relative to monocropping, optimization of row configuration effectively mitigated this effect. All intercropping patterns exhibited land equivalent ratios and water equivalent ratios greater than 1. Among treatments, N1 + M2S4 consistently performed best in terms of system yield, water productivity, nitrogen use efficiency, land equivalent ratio, and economic returns, indicating a strong synergy between spatial arrangement and nutrient management. Economically, N1 + M2S2 yielded the highest profit in 2022 (11,970.6 CNY·ha −1 ), only 4.4 % higher than that of N1 + M2S4, whereas N1 + M2S4 generated the maximum profit in 2023 (13,395.58 CNY·ha −1 ), demonstrating its stable economic advantage. Overall, considering productivity, resource use efficiency, economic returns and mechanization feasibility, N1 + M2S4 was identified as the optimal strategy for sustainable maize/soybean intercropping production on the Loess Plateau of China. • Intercropping increased system yield by 7.16–23.36 % over monocropping. • Two maize and four soybean rows (M2S4) enhanced maize growth and canopy structure, reducing shading on soybean. • Moderate nitrogen (150 kg N ha⁻¹) enhanced biomass, stem strength, and nitrogen use efficiency. • M2S4 with 150 kg N ha⁻¹ maximized yield, water, nitrogen, and land use efficiency, boosting economic returns.