Coupled effects of blended urea application under the ridge-furrow system on spring maize productivity and water-nitrogen use efficiency in the Loess Plateau

Ridge-furrow system significantly improves the yield and resource utilization efficiency of rain-fed spring maize, but its underlying mechanism with different urea application strategies remains unclear. This study conducted a field experiment of planting method (ridge-furrow system and flat planting) and urea application strategy (no urea, conventional urea, controlled release urea, and blended urea) in the Loess Plateau to assess the effects on spring maize productivity and resource use efficiency. Compared with flat planting, the ridge-furrow system significantly increased water productivity (18.80 %), nitrogen use efficiency (2.70 %), dry matter accumulation (16.34 %), and yield (19.71 %). Water productivity, evapotranspiration, nitrogen use efficiency, crop agronomic traits, and yield were optimized under blended urea application. Applying blended urea under the ridge-furrow system improved agronomic traits, yield, and resource use efficiency, and reduce NO 3 – -N leaching. Yield and its composition were closely related to water-nitrogen use efficiency and agronomic traits. Blended urea application under the ridge-furrow system improved agronomic traits by optimizing water-nitrogen use efficiency, thereby enhancing yield and its composition in rain-fed spring maize growing areas. Nitrogen use efficiency and water productivity were considered as the largest direct and indirect factors affecting yield formation, respectively. Blended urea application under the ridge-furrow system could be used as an optimal strategy for achieving high yield, high efficiency, and environmental sustainability in the rain-fed spring maize cultivation system. The results provide an important scientific reference for the development of sustainable field management strategy of spring maize cultivation in the Loess Plateau.