In situ 15N labeling reveals high soil N2 emission during anaerobic soil disinfestation period in a greenhouse vegetable production system

Background and aims

Greenhouse vegetable production (GVP) is expanding globally. High nitrogen (N) fertilizer application causes soil disease and nitrate residues. Anaerobic soil disinfestation (ASD), a common mitigation strategy, involves creating an anaerobic environment through soil flooding, plastic film covering, and greenhouse sealing, typically with organic C addition to expedite the process. These conditions can promote denitrification, causing nitrous oxide (N₂O) and dinitrogen (N₂) emissions, but this has rarely been reported.

Methods

¹⁵N labeling was used 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 N₂O, and 40.7 and 25.5 kg N ha⁻¹ for N₂, respectively. Organic fertilization significantly increased N₂O and N₂ emission. In Fertilizer, N emitted as N₂O and N₂ accounted for 0.3% and 14.5% of organic fertilizer, respectively. From days 1–6, the predominant gaseous N was N₂, with an N₂O/ (N₂O + N₂) ratio (R_N2O) of 0.007–0.015. From days 7–14, the N₂O proportion increased, with R_N2O of 0.21–0.75. Isotopic information showed that denitrification contributed to 48.9–51.2% and 27.1–36.7% of total N₂O and N₂ emissions.

Conclusion

Our findings emphasize the importance of N₂ emissions in N loss and provide a basis for studying the fate of N and developing measures to reduce N₂O emissions within GVP systems.