Tea Research Institute, Chinese Academy of Agriculture Sciences, Key Laboratory of Tea Biology and Resource Utilization of Tea, the Ministry of Agriculture, Hangzhou 310008, China.
Tea Research Institute, Chinese Academy of Agriculture Sciences, Key Laboratory of Tea Biology and Resource Utilization of Tea, the Ministry of Agriculture, Hangzhou 310008, China.
Sci Total Environ. 2020 May 15;717:137248. doi: 10.1016/j.scitotenv.2020.137248. Epub 2020 Feb 11.
Nitrogen (N) fertilizer is widely used in agricultural ecosystems and influences N transformation processes in the soil such as nitrification. However, whether nitrification is primarily dominated by ammonia-oxidizing bacteria (AOB) or archaea (AOA) under heavy N application is still under debate. In the present work, the effect of long-term (12 years) N fertilization on soil nitrification and the key influencing factors were investigated in acidic tea plantation soil that received four different rates of N application (0, 119, 285, and 569 kg N ha yr). Nitrification potential was measured and partitioned using chemical inhibitors. The abundance of functional genes involved in ammonia oxidation was quantified using quantitative polymerase chain reaction (qPCR). Ammonia-oxidizing communities were identified by shotgun metagenome sequencing. Potential nitrification rate in tea plantation soil was mainly dominated by autotrophic nitrification (PNR) (71-79%). PNR and heterotrophic nitrification (PNR) were both significantly increased by heavy N (569 kg ha) application. Moreover, PNR was mainly due to the contribution of AOB (52-66%) in N-treated soils, and N569 significantly increased the AOB contribution without affecting the AOA contribution. N569 increased the functional gene abundance of AOB and TAO100 (a non-halophilic γ-AOB) but decreased that of AOA. The dominant AOB (Nitrosomonas, Nitrosospira, and Nitrosococcus), AOA (Nitrososphaera and Nitrosopumilus) and commamox (Nitrospira) groups were profoundly altered by long-term N application rates. Partial least squares regression showed that total nitrification (PNR), PNR, and PNR were primarily explained by the functional gene abundance of nitrifiers whereas PNR and PNR were closely associated with soil and pruned litter properties. Moreover, structural equation modeling (SEM) revealed that long-term N application significantly and indirectly affected nitrification potential by directly influencing soil properties, pruned litter properties, and functional gene abundance. Understanding the relative contribution of AOA and AOB to nitrification may help to better regulate N fertilizer use in agricultural ecosystems.
氮 (N) 肥料广泛应用于农业生态系统，并影响土壤中的 N 转化过程，如硝化作用。然而，在大量 N 施用量下，硝化作用主要是由氨氧化细菌 (AOB) 还是古菌 (AOA) 主导，这仍然存在争议。在本研究中，通过在接受四种不同 N 施用量（0、119、285 和 569 kg N ha yr）的酸性茶园土壤中进行为期 12 年的长期施肥试验，研究了土壤硝化作用及其关键影响因素。通过化学抑制剂测量和划分硝化潜能，并使用定量聚合酶链反应 (qPCR) 定量测定参与氨氧化的功能基因丰度。通过鸟枪法宏基因组测序鉴定氨氧化群落。茶园土壤的潜在硝化速率主要由自养硝化 (PNR) (71-79%) 主导。在高 N（569 kg ha）处理下，PNR 和异养硝化（PNR）均显著增加。此外，在 N 处理土壤中，PNR 主要由 AOB（52-66%）贡献，N569 处理显著增加了 AOB 的贡献，而不影响 AOA 的贡献。N569 增加了 AOB 和 TAO100（一种非嗜盐性 γ-AOB）的功能基因丰度，但降低了 AOA 的丰度。长期 N 施用量显著改变了优势 AOB（硝化单胞菌、硝化刺菌和硝化球菌）、AOA（硝化螺旋菌和硝化浮霉菌）和 commamox（硝化螺旋菌）。偏最小二乘回归表明，总硝化（PNR）、PNR 和 PNR 主要由硝化功能基因丰度解释，而 PNR 和 PNR 与土壤和修剪后的凋落物特性密切相关。此外，结构方程模型（SEM）表明，长期 N 应用通过直接影响土壤特性、修剪凋落物特性和功能基因丰度，显著且间接地影响硝化潜力。了解 AOA 和 AOB 对硝化作用的相对贡献可能有助于更好地调节农业生态系统中的 N 肥料使用。
