Abstract Rice–rice–green manure rotations in south China are characterized by high efficiency and good environmental performance, and the application of green manure plays an important role in N management. Nitrification is a key process in N cycling and is highly correlated with the N utilization of crops and with leaching losses. As a potential N loss pathway, the nitrification process and nitrifiers as affected by green manuring are of critical importance. A pot experiment covering green manure-double rice rotation was conducted to evaluate the effects of green manure and N fertilizer on soil nitrification and to achieve a mechanistic understanding of underlying processes in an alkaline paddy soil. Soil nitrification potential (NP) and the recovered nitrification potential (RNP) were measured. Relative contributions of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in soil nitrification were studied using specific bacterial inhibitors. In the alkaline paddy soil, soil NP and nitrate concentrations were significantly decreased by green manuring but increased with increasing N fertilization. Soil nitrification was dominated by AOB and that the relative contributions of AOB to RNP ranged from 65% to 79% at different sampling stages despite the larger abundance of AOA amoA gene numbers. RNP and the contribution of AOB to RNP were significantly increased by N fertilizer, whereas the contribution of AOA was decreased by green manuring. We concluded that the application of inorganic N enhanced NP while green manures reduced it, which is consistent with the variation of observed soil nitrate concentrations. These results indicate that the utilization of winter green manure is an effective practice to improve N management in paddy rice.

中文翻译：

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绿肥通过改变氨氧化古菌和细菌的贡献来抑制典型稻田中的硝化作用

摘要 华南水稻-水稻-绿肥轮作具有效率高、环境效益好的特点，绿肥的施用在氮素管理中具有重要作用。硝化作用是氮循环的关键过程，与作物的氮利用和淋失损失高度相关。作为潜在的 N 损失途径，硝化过程和受绿肥影响的硝化菌至关重要。进行了绿肥-双稻轮作盆栽试验，以评价绿肥和氮肥对土壤硝化作用的影响，并实现对碱性稻田潜在过程的机理理解。测量了土壤硝化潜力 (NP) 和恢复硝化潜力 (RNP)。使用特定的细菌抑制剂研究了氨氧化古菌 (AOA) 和氨氧化细菌 (AOB) 在土壤硝化中的相对贡献。在碱性水稻土中，绿肥显着降低了土壤 NP 和硝酸盐浓度，但随着施氮量的增加而增加。土壤硝化以 AOB 为主，尽管 AOA amoA 基因数量较多，但在不同采样阶段，AOB 对 RNP 的相对贡献范围为 65% 至 79%。施氮显着提高了RNP和AOB对RNP的贡献，而绿肥则降低了AOA的贡献。我们得出的结论是，施用无机氮增加了 NP，而绿肥减少了它，这与观察到的土壤硝酸盐浓度的变化一致。