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首页> 外文期刊>Soil Science Society of America Journal >Mineral and Dissolved Organic Nitrogen Dynamics along a Soil Acidity-Fertility Gradient
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Mineral and Dissolved Organic Nitrogen Dynamics along a Soil Acidity-Fertility Gradient

机译：沿土壤酸度-肥力梯度的矿质和溶解有机氮动力学

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摘要

Mineral (NH+4 + NO-3) and dissolved organic nitrogen (DON) dynamics were investigated along a soil chronosequence in northern California that ranges in age from about 100 000 to 500 000 BP. Younger soils are slightly acidic and fertile supporting highly productive grasslands and mixed-conifer forests. Older soils are highly acidic and infertile supporting forests of dwarf (<3 m) conifers and Ericaceous species. This edaphic gradient provides an ideal opportunity to examine changes in N dynamics on soils that are progressively older and less fertile. We examined in situ net mineralization rates using closed-top tubes and we examined mineralization and nitrification rates using 15NH+4 and 15NO-3 pool dilution techniques. Net N mineralization rates per unit of organic C decreased as soil age increased. Net mineralization rates (per unit C) were more strongly related to differences in rates of immobilization than gross mineralization. However, gross mineralization results normalized to soil N levels (N activity basis) were similar across soil ages. A similar rate of N turnover across this edaphic gradient indicates that the size of the total N pool is an important factor regulating N mineralization. It further suggests that litter quality does not appreciably hinder N mineralization. Pool dilution of added 15NO-3 indicated that nitrification is active across all sites and that microbial assimilation consumed the majority of the NO-3 produced. Dissolved organic N makes a larger relative contribution to dissolved N in older soils indicating a shift in the dominant N cycling pathway from mineral to organic forms in older less fertile soils.
机译：矿物（NH + 4 + NO - 3 ）和溶解有机氮（DON）动力学 < / sup>在加利福尼亚北部的土壤年代顺序上进行了调查，其年龄范围从大约100000到500000 BP。年轻的 土壤略带酸性，肥沃，支持高产的草地和针叶林。较旧的土壤是矮（<3 m）针叶树 和白垩纪物种的高度 酸性和不育性支持林。这个渐层梯度提供了一个理想的机会，可以研究年龄逐渐增长且肥沃的土壤中氮素动态的变化。我们使用封闭管检查了原位净 矿化率，并使用 15 NH + 矿化率和硝化率> 4 和 15 NO - 3 池稀释技术。随着土壤年龄的增加，每单位有机碳的净氮矿化率降低。净矿化率（每单位C）与固定化率的差异 比总矿化度更强。但是， 总矿化结果归一化为土壤氮水平（N 活性基础）在不同土壤年龄之间都相似。在该深度梯度上，N周转率的比率 相似，表明总N池的 大小是调节N 矿化的重要因素。这进一步表明，凋落物的质量不会明显阻碍氮的​​矿化。添加的 15 NO - 3 的池稀释表明硝化作用在所有位点上都有效[sup> ，而微生物同化消耗了产生的大部分 NO - 3 。溶解的有机氮对较老土壤中的溶解氮具有较大的相对贡献 ，表明较低的 中主要的 N循环路径从矿物形式转变为有机形式肥沃的土壤。

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  • 来源
    《Soil Science Society of America Journal》 |2003年第3期|878-888|共11页
  • 作者

    Zengshou Yu; Tamara E. C. Kraus; Randy A. Dahlgren; William R. Horwath; Robert J. Zasoski;

  • 作者单位

    Department of Land, Air and Water Resources, One Shields Avenue, University of California, Davis, CA 95616;

    Department of Land, Air and Water Resources, One Shields Avenue, University of California, Davis, CA 95616;

    Department of Land, Air and Water Resources, One Shields Avenue, University of California, Davis, CA 95616;

    Department of Land, Air and Water Resources, One Shields Avenue, University of California, Davis, CA 95616;

    Department of Land, Air and Water Resources, One Shields Avenue, University of California, Davis, CA 95616;

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