不同土地利用方式土壤氨氧化微生物和反硝化微生物时空分布特征

研究不同土地利用方式下氮循环相关微生物在不同土壤剖面的分布，可为认识和理解土壤氮转化过程提供科学依据。土壤氨氧化微生物和反硝化微生物在调节氮肥利用率、硝态氮淋溶和氧化亚氮(N₂O)排放等方面有着重要作用。以北京郊区农田和林地两种土地利用方式为研究对象，分析土壤氨氧化潜势和亚硝酸盐氧化潜势在0—100 cm土壤剖面上的季节分布(春季和秋季),并通过实时荧光定量PCR方法表征土壤氨氧化和反硝化微生物的时空分布特征。结果表明，农田土壤氨氧化潜势、亚硝酸盐氧化潜势、氨氧化微生物和反硝化微生物丰度均显著高于林地土壤，且随土壤深度增加而显著降低。除氨氧化古菌amoA基因丰度在不同季节间无显著差异外，春季土壤氨氧化细菌(amoA基因)、反硝化微生物nirS、nirK和典型nosZ I基因的丰度均显著高于秋季。土壤有机质、总氮、NH~+₄-N、NO~-₃-N含量与氨氧化微生物和反硝化微生物的功能基因丰度显著相关。综上，不同土地利用方式下土壤氮循环相关微生物的丰度与土壤氮素的可利用性和转化过程紧密相关，研究结果对土壤氮素利用和养分管理提供...

Spatial-temporal patterns of soil ammonia oxidizer and denitrifier bacteria under different land-use types

Land use changes can affect soil nitrogen(N) transformation and greenhouse gas emission. Characterizing the distribution patterns of N-related microorganisms in different land uses along the soil profile provides significant information for understanding N cycling in ecosystems. Soil ammonia oxidation and denitrification play an important role in regulating nitrogen use efficiency, nitrate leaching and N₂O emission in soils. Ammonia oxidation, the conversion of ammonia to nitrite, is the critical step of nitrification and mainly performed by ammonia oxidizing archaea (AOA) and bacteria (AOB). The amoA gene has been used as a marker for both AOA and AOB for soil samples, while genes that encode key enzymes in nitrate reduction processes include nitrite reductase genes (nirS and nirK), nitrous oxide reductase gene (nosZ), and so on. Denitrification is a key process for controlling soil N availability and greatly influenced by land use change. However, the effect of land use conversion on the ammonia oxidization and denitrification are not well documented. This study aimed to investigate the spatial-temporal patterns of soil nitrification rate under different land-use types as well as the abundance of ammonia oxidizing microorganisms and denitrifiers using real-time PCR approach in spring and autumn. Soil samples were collected from maize land and woodland along the 0-100 cm soil depth in the suburban district of Beijing. Results showed that the potential ammonia oxidation (PAO), potential nitrite oxidation (PNO) rates, the abundance of N-related genes in maize land were significantly higher than those in woodland, which all showed a decreasing trend along the soil depth. Seasonal change had great impact on soil PNO, while no significant effects on PAO. The abundance of AOB amoA, denitrifiers nirS, nirK and nosZ I genes in spring was significantly higher than those in autumn, while AOA amoA abundance remained relatively stable across different seasons. The ratio of (nirS+nirK)/nosZ I reached the highest in the deep soil, indicating high capacity of denitrification. Correlation analysis found that soil organic matter, total N, ammonium and nitrate contents were positively correlated with the abundance of N-related genes. The relative contribution of specific N-related communities to soil nitrogen retention in soils merits further attention. In summary, the variation of ammonia oxidizing microorganisms and denitrifier abundance were closely related with soil available nitrogen contents and nitrification rates, which provides important information for soil nitrogen use and management in agricultural system. The performance of microorganisms in deep soil shed new light into understanding the denitrification process in the future studies.