Impact of tillage and crop rotation on light fraction and intra-aggregate soil organic matter in two Oxisols
Impact of tillage and crop rotation on light fraction and intra-aggregate soil organic matter in two Oxisols
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DOI：
10.1016/j.still.2007.01.002
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发表时间：
2007-09
影响因子：
6.5
通讯作者：
L. Zotarelli;B. Alves;S. Urquiaga;R. Boddey;J. Six
中科院分区：
文献类型：
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作者：
L. Zotarelli;B. Alves;S. Urquiaga;R. Boddey;J. Six
众所周知，免耕（NT）的做法，可以促进更大的股票土壤表层有机质（SOM）相比，常规耕作（CT），通过加强物理保护团聚体相关的C在温带土壤。然而，耕作，聚合和SOM之间的这种联系是不太好的热带土壤，如氧化土壤。本研究的目的是调查在巴西南部的两个地点不同的作物轮作和耕作制度的影响下，氧化土壤中的有机质稳定的潜在机制。土壤采样从两个农业实验地点（帕索丰多和隆德里纳）在巴西南部，与治疗比较不同的作物轮作NT和CT管理下，和参考土壤下的原生植被（NV）。从抗消化骨料中分离出游离轻组分（LF）和骨料内颗粒有机物（iPOM）。在与团聚体结合的总碳中，79-90%被发现在矿物部分中，但NT和CT之间没有差异。与此相反，翻耕大幅降低LF-C浓度在0-5cm的深度层在这两个网站。在同一深度层的NT系统在隆德里纳，iPOM-C的浓度更大时，豆科作物覆盖作物包括在旋转。在隆德里纳，0-5cm深度范围内总iPOM-C水平的顺序一般为NV>NT>CT，但NT与CT之间的差异远小于帕索丰多。在帕索丰多，在微团聚体中的细（53-250μm）iPOM组分中发现了最大浓度和不同耕作处理间的浓度差异。总之，即使没有总层次结构存在于这些Oxisol，我们的研究结果证实了稳定的概念POM-C内的微团聚体在免耕系统，特别是当绿色肥料包括在旋转。
It is well known that no-tillage (NT) practices can promote greater stocks of soil organic matter (SOM) in the soil surface layer compared to conventional tillage (CT) by enhancing the physical protection of aggregate-associated C in temperate soils. However, this link between tillage, aggregation and SOM is less well established for tropical soils, such as Oxisols. The objective of this study was to investigate the underlying mechanisms of SOM stabilization in Oxisols as affected by different crop rotations and tillage regimes at two sites in southern Brazil. Soils were sampled from two agricultural experiment sites (Passo Fundo and Londrina) in southern Brazil, with treatments comparing different crop rotations under NT and CT management, and a reference soil under native vegetation (NV). Free light fraction (LF) and intra-aggregate particulate organic matter (iPOM) were isolated from slaking-resistant aggregates. Of the total C associated with aggregates, 79–90% was found in the mineral fraction, but there were no differences between NT and CT. In contrast, tillage drastically decreased LF-C concentrations in the 0–5cm depth layer at both sites. In the same depth layer of NT systems at Londrina, the concentrations of iPOM-C were greater when a legume cover crop was included in the rotation. At Londrina, the order of total iPOM-C levels was generally NV>NT>CT in the 0–5cm depth interval, but the difference between NT and CT was much less than in Passo Fundo. At Passo Fundo, the greatest concentrations and differences in concentrations across tillage treatments were found in the fine (53–250μm) iPOM fractions occluded within microaggregates. In conclusion, even though no aggregate hierarchy exists in these Oxisols, our results corroborate the concept of a stabilization of POM-C within microaggregates in no-tillage systems, especially when green manures are included in the rotation.