Nitrogen losses caused by excess fertilizer application in agriculture are one of the main sources of non-point pollution. Biofertilizer has been considered as an effective alternative to synthetic nitrogen fertilizer, but the effectiveness and mechanism for controlling non-point pollution remains unclear. In this study, the effect of biofertilizer containing Bacillus subtilis on nitrogen loss in agricultural soil was investigated. Compared with the application of urea alone, the strategy of substituting 50% urea with biofertilizer reduced the nitrogen loss from farmland soil by 54%. Moreover, this strategy also increased nitrogen use efficiency by 11.2% and achieved a 5.0% increase in crop yield. Application of biofertilizer decreased the abundance of bacterial amoA gene and increased the abundance of narG, nirS, nirK, and nosZ genes in soil. This implied a decrease in nitrification and an increase in denitrification. Thus, it reduced the accumulation of NO₃⁻-N in soil and greatly reduced nitrogen runoff and leaching loss. In addition, biofertilizer decreased the abundance of nitrogen-fixing gene nifH by up to 2 times. Application of biofertilizer also increased the abundance of Bacteroidetes and Chloroflexi, which play important roles in degradation of soil organic matter. In conclusion, the biofertilizer regulated the microbial nitrogen transformation process in soil and reduced nitrogen loss from agroecosystems.

农业过量施肥导致的氮损失是面源污染的主要来源之一。生物肥料被认为是合成氮肥的有效替代品，但控制面源污染的有效性和机理仍不清楚。在这项研究中，研究了含有枯草芽孢杆菌的生物肥料对农业土壤氮素流失的影响。与单独施用尿素相比，用生物肥料替代50％尿素的策略使农田土壤的氮损失减少了54％。此外，该策略还使氮的利用效率提高了11.2％，并使作物产量提高了5.0％。生物肥料的施用降低了细菌amoA的丰度基因并增加了土壤中narG，nirS，nirK和nosZ基因的丰度。这意味着硝化作用的减少和反硝化作用的增加。因此，它减少了土壤中NO ₃ ^-- N的积累，并大大减少了氮的径流和淋失。此外，生物肥料将固氮基因nifH的丰度降低了多达2倍。生物肥料的应用还增加了拟杆菌和绿弯曲菌的含量，它们在土壤有机质的降解中起着重要的作用。总之，生物肥料调节了土壤中微生物氮的转化过程，并减少了农业生态系统中的氮损失。