Chemical fumigation and biofumigation are used to reduce soil-borne diseases in agricultural production systems; however, other essential soil processes such as the soil nitrogen (N) cycle may also be affected. This study compared the effects of chemical fumigation and biofumigation on soil net N mineralization, nitrification, denitrification, and soil nitrifier and denitrifier abundance. Six treatments were compared using soil microcosms over a 160-day incubation period: fumigation with chloropicrin; fumigation with metam sodium used alone (MS) or combined with barley plant residues (MSBR); biofumigation with mustard residues; addition of non-biofumigant barley residues; and an untreated control. Biofumigation did not inhibit soil nitrification, whereas chemical fumigation with MS (with or without barley) and chloropicrin inhibited nitrification for 16 and 64 days, respectively. Biofumigation, barley residues, and MSBR increased soil respiration, N₂O emission, and denitrification rates. However, biofumigation had lower denitrification and N₂O cumulative emissions and rates compared to barley residues, suggesting that biofumigation may reduce N₂O production pathways. All chemical fumigation treatments significantly decreased nitrifier gene abundance compared to biofumigation; however, only chloropicrin decreased the abundance of denitrifying genes. After 160 days, 22% of the added plant residue dry matter remained in the MSBR-treated soil, which was ∼2-fold greater than the barley-treated soil, indicating chemical fumigation may also affect the carbon cycle. Overall, these results suggest that chemical fumigation, especially with chloropicrin, has a greater impact on nitrification and nitrifier and denitrifier gene abundance than biofumigation with mustard residues.

化学熏蒸和生物熏蒸用于减少农业生产系统中的土壤传播疾病；然而，其他重要的土壤过程，如土壤氮 (N) 循环也可能受到影响。本研究比较了化学熏蒸和生物熏蒸对土壤净氮矿化、硝化、反硝化作用以及土壤硝化菌和反硝化菌丰度的影响。在 160 天的潜伏期内，使用土壤微观世界比较了六种处理方法：用氯化苦熏蒸；单独使用（MS）或与大麦植物残留物（MSBR）结合使用灭活钠熏蒸；芥末残留物的生物熏蒸；添加非生物熏蒸大麦残留物；和未经处理的对照。生物熏蒸不抑制土壤硝化作用，而用 MS（有或没有大麦）和氯化苦进行化学熏蒸分别抑制硝化作用 16 天和 64 天。生物熏蒸、大麦残留和 MSBR 增加了土壤呼吸，N₂ O 排放和反硝化率。然而，与大麦残留物相比，生物熏蒸具有较低的反硝化作用和 N ₂ O 累积排放和速率，表明生物熏蒸可能会减少 N ₂O 生产途径。与生物熏蒸相比，所有化学熏蒸处理都显着降低了硝化菌基因丰度；然而，只有氯化苦才能降低反硝化基因的丰度。160 天后，22% 的添加植物残留物干物质保留在 MSBR 处理的土壤中，比大麦处理的土壤高约 2 倍，表明化学熏蒸也可能影响碳循环。总体而言，这些结果表明化学熏蒸，尤其是氯化苦，对硝化作用、硝化作用和反硝化作用基因丰度的影响比芥末残留物的生物熏蒸作用更大。