The Influence of Soil Nematodes on N₂O Emissions Under Chemical and Organic Nitrogen Fertilization

Soil nematodes, the most abundant soil fauna, play a pivotal role in nitrogen cycling through their interactions with soil microorganisms, potentially influencing N₂O emissions. While it is well-established that N fertilization can increase N₂O emissions, the role of nematodes in modulating N₂O emissions across different N fertilization strategies remains underexplored. This study investigates the effect of soil nematodes on N₂O emissions under four N fertilization treatments: no nitrogen (CK), chemical fertilizer (CF), pig manure (PM), and green manure (GM). Over a 58-day soil microcosm incubation, we compared N₂O emissions with and without the presence of the entire soil nematode community across two soil textures—loamy sand and sandy loam. Our results revealed that soil texture, N fertilization, and nematode presence significantly influenced N₂O emissions. The most pronounced effect of nematodes was observed in loamy sand soil treated with PM, where nematodes contributed to a marked increase in N₂O emissions during the initial peak (0-5 days). In contrast, nematodes significantly elevated N₂O emissions from 5 to 58 days in sandy loam soil treated with GM. Both pig manure and green manure promoted nematode population growth; however, nematodes only notably enhanced nitrogen mineralization in unfertilized soil. These findings underscore the importance of incorporating soil fauna, particularly nematodes, into N₂O emission prediction and mitigation strategies for agricultural soils.