Optimizing the ratios of ridge-furrow mulching patterns and urea types improve the resource use efficiency and yield of broomcorn millet on the Loess Plateau of China

Ridge-furrow mulching patterns and nitrogen application boosted crop yields in arid and semi-arid regions. Nevertheless, their combined impacts on broomcorn millet growth were unclear. A two-year field experiment was conducted to investigate the impacts of three ridge-furrow mulching configurations [traditional planting without mulch(TP), and two ridge-furrow mulching ratios, namely 40 cm: 40 cm(RF40), and 40 cm: 80 cm (RF80)] and four urea type ratios [100 % conventional urea application(U), 30 % conventional urea combined with 70 % controlled release urea(U3C7), 70 % conventional urea combined with 30 % controlled release urea (U7C3), 100 % controlled release urea(C), and no nitrogen fertilizer treatment(N0)] on water/nitrogen use efficiency and yield of broomcorn millet on the Loess Plateau. Results showed that in 2021, compared to TP, RF40 had higher soil moisture content, improved WUE, and increased the dry matter accumulation, thereby boosting the yield of broomcorn millet by 13.42 % and 17.15 % under U7C3 and U3C7 treatments, respectively. Meanwhile, U3C7 and U7C3 treatments significantly increased N partial factor productivity, nitrogen use efficiency, nitrogen recovery efficiency, and improved agronomic traits of broomcorn millet by coordinating fertilizer release with crop growth. Notably, the combination of RF40 and U7C3 maximized resource utilization efficiency and grain yield, with yield and water use efficiency increase of 42.79 % and 35.46 %, respectively. Partial least squares path modeling analysis indicated that fertilizer regimes were the key factor affecting the yield of broomcorn millet. This study offers a scientific foundation for enhancing resource utilization efficiency in arid and semi-arid regions.