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首页> 外文学位 >The impact of maize and soybean cropping systems on carbon and nitrogen dynamics in soil organic matter.
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The impact of maize and soybean cropping systems on carbon and nitrogen dynamics in soil organic matter.

机译：玉米和大豆种植系统对土壤有机质碳氮动态的影响。

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摘要

Soil organic matter (SOM) is a carbon (C) and nitrogen (N) reservoir comprising a continuum of overlapping pools of different sizes, composition, turnover times and levels of significance to C and N cycling in terrestrial systems. The mineralization of SOM provides C, N and energy to microorganisms and N to plants. Soil C and N dynamics are linked to each other and N is usually the limiting substrate for C microbial turnover. Soil C and N demand increase with higher crop yields and risks of depletion of soil reserves arise when removals are larger than inputs. Assessing the C and N dynamics in sensitive SOM pools is a key to measure changes in soil quality under intensive agriculture. Short-term (18-month) C and N dynamics was studied using stable isotopes ( 15N and 13C) in four SOM pools under maize-soybean cropping systems.; Temporal changes in total soil C (TSC) and N (TSN) were related to the amount of C and N inputs and removals each cycle. The LF and MHA were the most labile fractions with greater sensitivity to C and N of residue inputs. The LF displayed the largest seasonal fluctuation in C and N gains and removals. The change in 13C and 15N enrichment revealed the sequence of C and N turnover as LF > MHA > CaHA > Humin. Biological activity dominates the C and N turnover in the LF and MHA due to their simpler chemical composition and reduced protection by minerals while the turnover of CaHA and Humin suggest that abiotic processes dominate turnover. The contribution of individual fractions to TSN follows Humin-N > CaHA-N > MHA-N > LF-N. Manipulation of C and N cycling in agricultural ecosystems depends on the rate and timing of C and N additions to soil, the removals at harvest and the changes in the physical environment. TSC gains were measured only in systems attaining high crop productivity.
机译：土壤有机质（SOM）是碳（C）和氮（N）的储集层，包括不同大小，组成，周转时间和对陆地系统中C和N循环的重要意义的重叠池的连续体。 SOM的矿化为微生物提供了C，N和能量，为植物提供了N。土壤碳和氮的动力学相互联系，氮通常是碳微生物转化的限制底物。随着作物产量的增加，土壤碳和氮的需求增加，当清除量大于投入量时，土壤储量就会枯竭。评估敏感的SOM池中的碳和氮动态是衡量集约农业条件下土壤质量变化的关键。在玉米-大豆种植系统下，在四个SOM库中使用稳定同位素（15N和13C）研究了短期（18个月）碳和氮动力学。土壤总碳（TSC）和氮（TSN）的时间变化与每个循环中碳和氮的输入和清除量有关。 LF和MHA是最不稳定的馏分，对残留物输入的C和N敏感性更高。 LF显示出C和N获取和清除的最大季节性波动。 13C和15N富集的变化揭示了C和N周转的顺序为LF> MHA> CaHA> Humin。由于LF和MHA的化学组成更简单，且矿物质的保护作用降低，因此其生物活性主导着LF和MHA的碳和氮转化，而CaHA和腐殖质的转化则表明非生物过程主导了碳和氮的转化。各个部分对TSN的贡献遵循Humin-N> CaHA-N> MHA-N> LF-N。在农业生态系统中对碳和氮循环的控制取决于向土壤中添加碳和氮的速率和时间，收获时的清除量以及自然环境的变化。仅在获得高农作物生产力的系统中测量了TSC的收益。

著录项

  • 作者

    Legorreta-Padilla, Felipe de Jesus.;

  • 作者单位

    The University of Nebraska - Lincoln.;

  • 授予单位 The University of Nebraska - Lincoln.;
  • 学科 Agriculture Soil Science.; Agriculture Agronomy.
  • 学位 Ph.D.
  • 年度 2005
  • 页码 261 p.
  • 总页数 261
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 土壤学;农学（农艺学）;
  • 关键词

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