Appropriate nitrogen application rate with decreased basal/topdressing ratio improves yield, quality, water productivity, and N-use efficiency of forage maize in a rainfed region
Zhongli Li, Wei Gao, Congze Jiang, Yongli Lu, Muhammad Kamran, Xianlong Yang
Abstract
Crop cultivation in rainfed agricultural regions globally faces the challenges of water scarcity and irrational nitrogen (N) fertilizer application, causing fluctuating yields, reduced N-use efficiency, and increased environmental pollution. A two-year field experiment was conducted from 2021 to 2022 in a typical rainfed region of northwestern China to investigate the effects of four N application rates (0, 90, 180, 270 kg hm −2 ) and two basal/topdressing ratios (2:8 and 4:6) and their interactions on the growth, dry matter (DM) yield, forage quality, water productivity (WP), and N-use efficiency of forage maize ( Zea mays L.). The LAI, DM yield, crude protein (CP) yield, food equivalent unit yield (FEU yield), WP DM , WP CP , WP FEU and aboveground N uptake of forage maize significantly ( P < 0.05) increased with the increase in N application rate from 0 to 180 kg hm −2 . The soil NO 3 -N accumulation in 0–200 cm soil layer increased linearly, whereas the partial factor productivity of applied N (PFP N ) and N recovery efficiency (RE N ) decreased linearly with the increase in N rates. The regression analysis further revealed that the DM yield, FEU yield, WP DM , WP FEU , N uptake, PFP N and RE N at all N rates were generally higher at 2:8 basal/topdressing ratio compared to 4:6 ratio. The required nitrogen application rates to achieve maximum values for DM yield, FEU yield, WP DM , WP FEU and above-ground N uptake under the 2:8 basal/topdressing ratio were reduced by 3.3 %, 7.3 %, 7.3 %, 9.6 % and 13.8 %, respectively, compared to the 4:6 ratio. Therefore, N application rate of 180 kg hm −2 and basal/topdressing ratio of 2:8 is recommended as a proper N fertilization management for achieving high yield, quality, water productivity, and N-use efficiency of forage maize in northwestern China and areas with similar climatic conditions.