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首页> 外文期刊>Global change biology >Accumulation of nitrogen and microbial residues during 2000 years of rice paddy and non-paddy soil development in the Yangtze River Delta, China.
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Accumulation of nitrogen and microbial residues during 2000 years of rice paddy and non-paddy soil development in the Yangtze River Delta, China.

机译：中国长江三角洲2000年稻田和非稻田土壤发育过程中氮和微生物残留的累积

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摘要

Lowland rice paddy soils may accumulate significant amounts of organic matter. Our aim was to investigate the role of prolonged paddy management on the nitrogen (N) status of the soils, and to elucidate the contribution of bacteria and fungi to long-term N accumulation processes. For this purpose, we sampled a chronosequence of 0-2000 years of rice cropping with adjacent non-paddy systems in the Bay of Hangzhou, China. The samples were analyzed for bulk density, total, mineral and microbial N (Nmic), and amino sugars as markers for microbial residues. The results showed that during the first 100 years of land embankment, both paddy and non-paddy soils accumulated N at a rate of up to 61 and 77 kg ha-1 per annum, reaching steady-state conditions after 110-172 years, respectively. Final N stocks in paddy fields exceeded those of the non-paddies by a factor of 1.3. The contribution of amino sugars to total N increased to a maximum of 34 g N kg-1 N in both land-use systems, highlighting a significant accumulation of N in microbial residues of the surface soils. Correspondingly, the ratio of Nmic to microbial residue-N decreased to a constant value. In the paddy subsoils, we found that bacterial residues particularly contributed to the pool of microbial residue-N. Nevertheless, the absolute contents of amino sugars in paddy subsoils decreased during the last 1700 years of the chronosequence. We conclude that under paddy cultivation, soil microorganisms may accumulate parts of this N in their residues despite low overall N availability. However, this N accumulation is limited to initial stages of paddy soil development and restricted to the surface horizons, thus challenging its sustainability with future land-use changes.
机译：低地稻田土壤可能积聚大量有机物。我们的目的是调查长期稻田管理对土壤氮（N）状况的作用，并阐明细菌和真菌对长期氮积累过程的贡献。为此，我们在中国杭州湾附近的非稻田系统中，对0-2000年水稻种植的时间序列进行了采样。分析了样品的堆积密度，总氮，矿物质和微生物氮（N ）以及氨基糖作为微生物残留的标记。结果表明，在路堤的前100年中，稻田和非稻田土壤均以每年高达61和77 kg ha -1 的速率积累氮，达到稳态之后分别为110-172年。稻田中最终的N量超出非稻田的1.3倍。在两种土地利用系统中，氨基糖对总氮的贡献增加到最大34 g N kg -1 N，这突出了表层土壤微生物残留中氮的大量积累。相应地，N 与微生物残基-N之比降低至恒定值。在稻田土壤中，我们发现细菌残留特别有助于微生物残留-N的积累。然而，在稻米次生土壤中，氨基糖的绝对含量在时间序列的最后1700年期间下降了。我们得出的结论是，在水稻种植下，尽管总氮的利用率很低，但土壤微生物仍会在其残留物中积累部分氮。但是，这种氮的积累仅限于水稻土发展的初期阶段，并且仅限于地表视野，因此，随着未来土地利用的变化，其可持续性受到了挑战。

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