Integrated nitrogen management enhances forage yield and quality while mitigating greenhouse gas emissions in...

Nitrogen fertilizer is essential for increasing forage productivity but often comes at the cost of higher greenhouse gas (GHG) emissions, which raises concerns about long-term sustainability. To address this challenge, the present study evaluated an integrated nitrogen fertilizer management by combining organic and chemical nitrogen sources, aimed to improve forage yield and nutritive quality while mitigating GHG emissions in alfalfa-grass mixed grassland. A two-year field experiment (2023-2024) was conducted in arid grassland to evaluate the effects of litter (LT), sheep excreta (SE), and chemical nitrogen fertilizer (CF) applied individually or in combination (CF + LT, LT + SE, CF + SE) on hay yield, forage quality, soil mineral nitrogen, and GHG fluxes. The results revealed that combined applications, particularly CF + SE, improved forage quality, reflected a decrease in neutral detergent fiber (37.7-37.2%) and acid detergent fiber (37.7-34.83%) and an increase in crude protein (115.0-143.8%) and hay yield (108.8-91.1%) in 2023 and 2024 compared to unfertilized control (CK). Soil nitrate and ammonium varied significantly, with CF + LT showing the highest nitrate contents. In both years, the highest N₂O emissions were evident with CF, while CF + SE reduced cumulative N₂O emissions by 45.5-39.2% compared to CF. Global warming potential and greenhouse gas emissions intensity were highest under CF, while CF + SE reduced them by 47.6-41.3% and 51.8-47.6% compared to CF in 2023-2024, respectively. Integrated fertilizer treatments effectively balanced the increase in forage yield with lower global warming potential and greenhouse gas emission intensity. Overall, results demonstrated that integrated nitrogen fertilizer management can improve productivity while minimizing environmental concerns, offering a sustainable management practice for cultivated grasslands in arid regions.