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Microbial transformation of nitrogen in soils of various ecosystems

机译：不同生态系统土壤中氮的微生物转化

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Relative contributions of bacteria and fungi in N cycling processes in soils of natural ecosystems and agroecosystems were determined in laboratory experiments. Measurements of biomass of bacteria and fungi, selective inhibition of their activities in the soils and comparisons of activities of inoculated microbial strains in sterile soils with rates of N processes in native soils were performed. Fungi play a leading role in microbial immobilization of N. Fungal biomass dominates (60%-90%) in the majority of soils, particularly, in natural ecosystems. Synthesis of melanin and melanin-chitin complexes by fungi is one of key mechanism of accumulation soil organic N. Fungi were responsible for most of ammonification of peptone to NH_4~+ in the forest soddy-podzolic soil. They had an equal role with bacteria in ammonification in the arable soil. Contribution of heterotrophic microorganisms (mainly fungi) in NO_3~- production was highest in the soil under mature spruce. Its contribution was much less (10%-40%) in soils of other natural ecosystems. Autotrophic nitrifying bacteria were almost entirely responsible for NO_3~- formation in cultivated soils. Fungi attributed less than few percents to denitrification. Functional capacities of bacteria and fungi in N processes in many aspects have duplicative and additive character. It could be considered as a factor of resiliency of N cycle in terrestrial ecosystems. Fungi cause maintenance and long-term retention of N in soils. Bacteria intensify N turnover, but elevates also N losses from soils due to their major role in nitrification and denitrification. Destruction of native vegetation and farming leads to a decrease of fungal participation and an in the increase bacterial role in N cycling. Alternative agricultural systems with a high level of fungal biomass could be more effective in retaining soil N capital than conventional systems.
机译：通过实验室实验确定了细菌和真菌在自然生态系统和农业生态系统的土壤中氮循环过程中的相对贡献。进行了细菌和真菌生物量的测量，对土壤中细菌和真菌活性的选择性抑制以及无菌土壤中接种的微生物菌株的活性与天然土壤中N进程的比率的比较。真菌在固定化N的微生物中起着主导作用。在大多数土壤中，尤其是在自然生态系统中，真菌的生物质占主导（60％-90％）。真菌合成黑色素和黑色素-几丁质配合物是土壤有机氮积累的关键机制之一。真菌是森林深水土壤中蛋白of氨化为NH_4〜+的主要原因。它们与细菌在耕作土壤中的氨化作用相同。在成熟云杉下，土壤中NO_3〜-的异养微生物（主要是真菌）的贡献最大。在其他自然生态系统的土壤中，它的贡献要少得多（10％-40％）。自养硝化细菌几乎完全负责耕作土壤中NO_3〜-的形成。真菌将反硝化作用归因于不到百分之几。 N过程中细菌和真菌的功能能力在许多方面具有重复性和累加性。可以将其视为陆地生态系统中N循环的复原力因素。真菌会导致土壤中氮的维持和长期保留。细菌增加了氮的转化，但由于氮在硝化和反硝化中的主要作用，也增加了土壤中的氮损失。破坏天然植被和耕种导致真菌参与减少，并增加了氮循环中细菌的作用。与常规系统相比，具有高真菌生物量水平的替代性农业系统在保留土壤氮素方面可能更有效。

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