Organic fertilizer can enhance soil health and multifunctionality in agroecosystems, but its impact on soil-borne greenhouse gas emissions needs mitigation. Fungal denitrification significantly contributes to NO emissions in carbon-rich soils; yet, the interactions between bacterial and fungal denitrifers under organic fertilizer amendment, remain unclear. Here, we investigated the rates and proportions of NO and N emissions, along with the interactions between fungal and bacterial denitrifiers in a high nitrogen (N) loading arable soil subjected to four treatments: ⅰ) Control, ⅱ) organic fertilizer (Manure), ⅲ) synthetic fertilizer (Urea), and ⅳ) synthetic plus organic fertilizer (Urea + Manure). Results showed that NO and N fluxes increased by 35.4 and 7.7 folds, respectively, in the Manure treatment compared to Control treatment. And these fluxes increased by 62.9 and 37.0 folds, respectively, in the Manure + Urea treatment compared to Urea treatment. Meanwhile, the contribution of fungal denitrification to NO emissions significantly increased in both Manure and Urea + Manure treatments, due to the significant enrichment of keystone fungal denitrifiers like among bacterial and fungal denitrifiers’ co-occurrence networks. Additionally, NO/(NO + N) ratio significantly decreased in the Manure and Urea + Manure treatments, which was primarily driven by significant enrichment of keystone bacterial denitrifiers carrying gene such as , , and . These bacteria possess complete denitrification capability and can synergize with fungal denitrifiers, enhancing NO reduction. Overall, our findings suggest that organic fertilizer amendment in high N loading arable soils decreases NO/(NO + N) ratio mainly by enhancing fungal-bacterial denitrifier mutualism.

中文翻译：

---

有机肥改良剂通过增强高氮负荷耕地土壤中细菌和真菌反硝化菌之间的共生来降低 N2O/(N2O+N2) 比


有机肥料可以增强土壤健康和农业生态系统的多功能性，但其对土壤温室气体排放的影响需要减轻。真菌反硝化作用显着增加了富碳土壤中的 NO 排放；然而，有机肥改良下细菌和真菌反硝化素之间的相互作用仍不清楚。在这里，我们研究了经过四种处理的高氮 (N) 负荷耕地中 NO 和 N 排放的速率和比例，以及真菌和细菌反硝化菌之间的相互作用：ⅰ）对照，ⅱ）有机肥料（粪肥）， ⅲ）合成肥料（尿素），和ⅳ）合成加有机肥料（尿素+粪肥）。结果表明，与对照处理相比，粪便处理中的 NO 和 N 通量分别增加了 35.4 倍和 7.7 倍。与尿素处理相比，粪肥+尿素处理的这些通量分别增加了 62.9 倍和 37.0 倍。同时，由于关键真菌反硝化菌（如细菌和真菌反硝化菌的共生网络）的显着富集，在粪肥和尿素+粪肥处理中，真菌反硝化对 NO 排放的贡献显着增加。此外，在粪肥和尿素+粪肥处理中，NO/（NO + N）比率显着下降，这主要是由于携带 、 和 等基因的关键细菌反硝化菌显着富集所致。这些细菌具有完全的反硝化能力，可以与真菌反硝化菌协同作用，增强NO还原。总体而言，我们的研究结果表明，高氮负荷耕地中的有机肥改良剂主要通过增强真菌-细菌反硝化菌的互利作用来降低 NO/(NO + N) 比率。