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Nitrogen balance in century-old wheat experiments

机译：氮气平衡在世纪历史的小麦实验中

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摘要

Managing nitrogen (N) inputs to sustain high yields while minimizing losses to adjacent environments remains among the foremost aims in agroecosystems. We studied the N balance in a study established in 1911 at Lethbridge, AB, Canada. The experiment includes three cropping systems - continuous wheat (W), fallow-wheat-wheat (FWW), and fallow-wheat (FW)-with a factorial of two N rates (0 and 45 kg N ha(-1)) and two phosphorus (P) rates (0 and 20 kg P ha(-1)) superimposed beginning in 1967. In unfertilized subplots, grain yields generally increased for the first eight decades, but then declined, perhaps partly because of growing N deficiency. Yield response to N increased over time, especially under continuous cropping and when co-applied with P. Soil N concentration in the surface 15 cm declined in the first few decades, and then approached an apparent steady state. Application of N increased soil N, roughly in proportion to the amount of residue returned. For the first half-century (1911-1967), N removal was approximately equivalent to the loss of soil N in the surface 15 cm. Since then, however, when the soil organic N was near steady state, removals of N in grain exceeded N inputs by approximately 20-30 kg N ha(-1) yr(-1), suggesting an input from outside sources, perhaps partly from atmospheric NH3. This study demonstrated the importance of long-term experiments in evaluating the N balance of cropping systems, and indicated the potential significance of non-fertilizer N inputs from outside sources in such ecosystems.
机译：管理氮气（n）输入以维持高收益率，同时最大限度地减少对邻近环境的损失，仍然是农业生物系统的目标。我们研究了1911年在加拿大AB的1911年建立的一项研究中的N平衡。该实验包括三种种植系统 - 连续小麦（W），休耕小麦（FWW）和休耕小麦（FW） - 为两种率（0和45 kg n（-1））和从1967年开始叠加的两种磷（P）速率（0和20kg p ha（-1））。在未受精的子尺中，谷物产量通常增加了前八十年，但随后可能部分衰落，也可能是不血糖。对N的产量反应随着时间的推移而增加，特别是在连续作物下，当在前几十年中，在表面15cm的土壤N浓度下降，然后接近明显的稳态。 N增加的土壤N增加，大致与返回的残留量成比例。对于上半年（1911-1967），N除去近似相当于表面15厘米的土壤N的损失。然而，从那时起，当土壤有机N接近稳态时，谷粒中的n被超过n个输入，由大约20-30kg n（-1）Yr（-1），表明来自外部来源的输入，也许部分从大气NH3。本研究表明了长期实验在评估种植系统的N平衡方面的重要性，并表明了在这种生态系统中的外部来源的非肥料N投入的潜在意义。

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  • 来源
    《Canadian Journal of Soil Science》 |2017年第4期|共12页
  • 作者

    Karimi Rezvan; Janzen H. H.; Smith E. G.; Ellert B. H.; Krobel R.;

  • 作者单位

    Agr &

    Agri Food Canada Lethbridge Res &

    Dev Ctr 5403-1 Ave South POB 3000 Lethbridge AB T1J 4B1 Canada;

    Agr &

    Agri Food Canada Lethbridge Res &

    Dev Ctr 5403-1 Ave South POB 3000 Lethbridge AB T1J 4B1 Canada;

    Agr &

    Agri Food Canada Lethbridge Res &

    Dev Ctr 5403-1 Ave South POB 3000 Lethbridge AB T1J 4B1 Canada;

    Agr &

    Agri Food Canada Lethbridge Res &

    Dev Ctr 5403-1 Ave South POB 3000 Lethbridge AB T1J 4B1 Canada;

    Agr &

    Agri Food Canada Lethbridge Res &

    Dev Ctr 5403-1 Ave South POB 3000 Lethbridge AB T1J 4B1 Canada;

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  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 土壤学;
  • 关键词

    nitrogen balance; long term; rotation; yield; fertilizer;

    机译：氮气平衡;长期;旋转;产量;肥料;

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