Soil N2O and N2 emissions during anaerobic soil disinfestation period in a greenhouse vegetable production system: quantified by in situ 15N labeling method

Background and Aims: Greenhouse vegetable production (GVP) is expanding worldwide. The high application of nitrogen (N) fertilizers has caused soil diseases and nitrate residue. Farmers usually adopt anaerobic soil disinfestation (ASD), involving organic carbon addition, extensive irrigation, plastic films laying, and greenhouse sealing during the summer fallow. These conditions may promote denitrification, causing nitrous oxide (N ₂ O) and dinitrogen (N ₂ ) emissions. However, this is rarely reported. Methods: We used ¹⁵N labeling for in situ monitoring of N₂O and N₂ emissions during ASD in a GVP system in Shouguang, Northern China. Two treatments were implemented: conventional organic fertilization (Fertilizer) and a control (No-fertilizer), with continuous monitoring over 14 days. Results: Within 14 days, cumulative gaseous N emissions in Fertilizer and No-fertilizer treatments were 0.82, 0.47 kg N ha ^-1 for N ₂ O, and 40.7 and 25.5 kg N ha ^-1 for N ₂ , respectively. Organic fertilization significantly increased N ₂ O and N ₂ emission. From days 1–6, the predominant gaseous N was N ₂ , with an N ₂ O/ (N ₂ O + N ₂ ) ratio (R _N2O ) between 0.007 and 0.015. From days 7–14, N ₂ O proportion increased, with R _N2O ranging from 0.21 to 0.75. Isotopic information showed that denitrification contributed to 48.9%–51.2% and 27.1%–36.7% of total N ₂ O and N ₂ emissions. The structural equation model showed that high soil temperature during ASD significantly reduced N ₂ O emissions. Conclusion: Our findings emphasize the importance of N ₂ emissions in N loss and provide a basis for studying the fate of N, as well as developing measures to reduce N ₂ O emissions within GVP systems.