Biofertilizer and organic fertilizer (OF) are potential alternative strategies for agriculture sustainability. However, their effects on soil gross nitrogen (N) transformation and the underlying mechanisms remain largely unknown. Therefore, in this study, using (BA) as a biofertilizer agent, a N tracer was employed to quantify soil gross N transformation rates in acidic soils under tea cultivation with four treatments: no fertilizer application (F0, control), only BA application (BA treatment), only OF application (OF treatment), and BA plus OF applications (BAOF treatment). Compared with F0 treatment, BA and OF treatments increased soil nitrate (NO) and total inorganic N concentrations. The gross rates of total organic N mineralization (M) and total NH immobilization were significantly decreased by BA and BAOF treatments but increased by OF treatment. Soil microbial biomass N concentration; 4-β-N-acetylglucosaminidase (NAG), leucine aminopeptidase (LAP), and urease activities; and abundance were decreased by BA and BAOF treatments, whereas NAG and LAP activities and abundance were increased by OF treatment; these modifications were probably responsible for the opposite effect on M. Meanwhile, BA, OF, and BAOF treatments significantly increased the gross autotrophic nitrification (O) rate by 105.2%, 270.5%, and 129.6%, respectively, which was attributed to increased soil pH and ammonia-oxidizing archaea abundance. BAOF treatment led to a higher gross NO immobilization (I) rate than F0 treatment. The net NO production, which indicates N loss risk, increased with BA and OF treatments and decreased with BAOF treatment. Thus, BA and OF applications increased soil N availability and N loss risk associated with enhanced O, whereas BAOF treatment reduced N loss risk by enhancing I. This study provides insights into the mechanisms underlying the effects of OF and BA applications on N availability and N loss risk in acidic soils, especially emphasizes the effects of OF plus BA applications on soil N availability and N loss, which would be great benefit for agricultural production and environment.

中文翻译：

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有机肥和解淀粉芽孢杆菌通过改变酸性土壤中不同的矿化-固定化周转率来促进土壤氮的有效性

生物肥料和有机肥料（OF）是农业可持续发展的潜在替代策略。然而，它们对土壤总氮（N）转化的影响及其潜在机制仍然很大程度上未知。因此，本研究以（BA）作为生物肥料，采用氮示踪剂量化了茶树栽培酸性土壤中土壤总氮转化率，并进行了四种处理：不施肥（F0，对照），仅施用BA（ BA 治疗）、仅应用 OF（OF 治疗）和 BA 加 OF 应用（BAOF 治疗）。与F0处理相比，BA和OF处理增加了土壤硝酸盐（NO）和总无机氮浓度。BA和BAOF处理显着降低了总有机氮矿化（M）和总NH固定率，但OF处理则增加了总有机氮矿化（M）和总NH固定率。土壤微生物量氮浓度；4-β-N-乙酰氨基葡萄糖苷酶 (NAG)、亮氨酸氨基肽酶 (LAP) 和脲酶活性；BA和BAOF处理降低了NAG和LAP的活性和丰度，而OF处理增加了NAG和LAP的活性和丰度；这些修改可能对 M 产生相反的影响。同时，BA、OF 和 BAOF 处理使总自养硝化 (O) 率分别显着增加 105.2%、270.5% 和 129.6%，这归因于土壤的增加pH 值和氨氧化古菌丰度。BAOF 处理导致比 F0 处理更高的总 NO 固定 (I) 率。净 NO 产量（表明氮损失风险）随着 BA 和 OF 处理而增加，而随着 BAOF 处理而减少。因此，BA 和 OF 施用增加了与增强 O 相关的土壤氮有效性和氮损失风险，而 BAOF 处理通过增强 I 降低了氮损失风险。本研究深入了解 OF 和 BA 施用对氮有效性和氮的影响机制。酸性土壤中的损失风险，特别强调了OF+BA施用对土壤氮素有效性和氮素损失的影响，这对农业生产和环境将产生巨大的好处。