Solar greenhouse vegetable fields have been found to be hotspots of nitrous oxide (N₂O) emissions in China, mainly due to excessive manure application and irrigation. Pulses of N₂O emissions have been commonly reported by field monitoring works conducted in greenhouse fields, though their significance regarding total N₂O emissions and the driving mechanism behind them remain poorly understood. N₂O fluxes were monitored in situ using a static opaque chamber method in a typical greenhouse vegetable field. Then, laboratory incubations were conducted under different soil moisture and manure application gradients to monitor nitrous oxide emissions and related soil properties, using a robotized incubation system. Field monitoring showed that the occurrence of clear N₂O emission bursts closely followed fertilization and irrigation events, accounting for 76.7% of the annual N₂O efflux. The soil N₂O flux increased exponentially with the water-filled pore space (WFPS), causing extremely high N₂O emissions when the WFPS was higher than 60%. During the lab incubation, emission bursts led to N₂O peaks within 40 h, synchronously changing with the transit soil NO₂⁻. An integrated analysis of the variations in the gas emission and soil properties indicated that the denitrification of transit NO₂⁻ accumulation was the major explanation for N₂O emission bursts in the greenhouse filed. Nitrous oxide emission bursts constituted the major portion of the N₂O emissions in the Chinese greenhouse soils. Nitrite (NO₂⁻) denitrification triggered by fertilization and irrigation was responsible for these N₂O emission pulses. Our results clarified the significance and biogeochemical mechanisms of N₂O burst emissions; this knowledge could help us to devise and enact sounder N₂O mitigation measures, which would be conducive to sustainable development in vegetable greenhouse fields.

A two-year field experiment was conducted to explore the effects of conventional flood irrigation (CI), and micro-sprinkler irrigation (SI) under three topdressing nitrogen levels (N1, 45 kg·ha⁻¹; N2, 90 kg·ha⁻¹; N3, 135 kg·ha⁻¹) on flag leaf physiology, root growth, and grain yield (GY) of winter wheat in the Huaibei Plain (HP). Results showed that higher N significantly decreased the soil moisture content, but SI had higher moisture than CI at the same N level. N2 and N3 significantly increased leaf area index (LAI) compared with N1, and the LAI in SI was higher than in CI. Chlorophyll content in N2 and N3 was significantly higher than in N1 during the grain filling stage, and SI further enhanced the content under the same N level—likely because higher N increased flag leaf antioxidant enzyme activity, while SI outperformed CI. At the anthesis stage, N2 had the highest root length density below 30 cm soil depth, with SI exceeding CI at the same N level. Therefore, N2 and N3 significantly increased dry matter accumulation at maturity (DMM), and the contribution rate of post-anthesis dry matter accumulation to GY (CR). SI further enhanced DMM and CR vs CI at the same N level. Compared to N1, N2 and N3 increased GY by 23.52% and 23.13%, respectively. SI significantly enhanced GY, ranging from 6.10% to 16.99% than CI. Overall, micro-sprinkler irrigation with optimal nitrogen application at jointing and booting stages effectively promoted root growth, enhanced leaf stress resistance, and delayed leaf senescence during grain filling, resulting in improved wheat yield in the HP.