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Mechanisms of aggregate breakdown in (sub) tropical soils: Effects of the hierarchical resistance

Thomaz, Edivaldo L. ; Araujo-Junior, Cezar F. ; R. S. Vendrame, Pedro ; de Melo, Thadeu R

Catena (Giessen), 2022-09, Vol.216, p.106377, Article 106377 [Periódico revisado por pares]

Elsevier B.V

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  • Título:
    Mechanisms of aggregate breakdown in (sub) tropical soils: Effects of the hierarchical resistance
  • Autor: Thomaz, Edivaldo L. ; Araujo-Junior, Cezar F. ; R. S. Vendrame, Pedro ; de Melo, Thadeu R
  • Assuntos: Aggregate size ; Forest soils ; Soil aggregation ; Soil erodibility ; Soil organic carbon ; Sustainability
  • É parte de: Catena (Giessen), 2022-09, Vol.216, p.106377, Article 106377
  • Descrição: •Four mechanisms of aggregates breakdown in Oxisols were tested.•Hierarchy resistance exist according to aggregates size.•The larger the aggregate, the lower their resistance to abrasion and raindrop impact.•The lower the aggregate, the lower their resistance to slaking (fast wetting)•Silicon-aluminum-iron oxides are associated with different breakdown mechanisms. The soil system is a dynamic component of the earth. Aggregate stability is critical for soil quality and ecosystem services. In tropical and subtropical soils, the role of clay, soil organic carbon, aluminum, and iron oxides on aggregate stability is somewhat controversial. In addition, aggregates develop a hierarchical organization; however, this process is poorly evaluated in the context of aggregate stability on different breakdown mechanisms such as raindrop impact, slaking (entrapped air), breakdown by differential swelling, and abrasion. Therefore, the objective of this study was: 1) to evaluate the aggregate stability of (sub) tropical soils in terms of four different breakdown mechanisms; 2) to ascertain the existence of hierarchical resistance to break down mechanism of pre-selected aggregates classes; 3) to determine whether soil chemical–mineralogical attributes influence aggregate stability. Five Oxisols originated from igneous rocks along a transect were evaluated. The soil aggregate stability responded according to hierarchical resistance, but differently to each breakdown mechanism: abrasion, slaking, differential swelling, and raindrop impact. Overall, the larger aggregates (4–8 mm) corresponded to a lower resistance to abrasion and raindrop impact. In contrast, the smaller aggregates (1–2 mm) were more affected by slaking than raindrop impact. Soil organic carbon, except for large aggregates, and soil texture did not show a significant role on aggregate stability. Silicon oxides increased the resistance to abrasion, while iron oxides increased the resistance to slaking. In contrast, aluminum oxides decreased the aggregate stability (slaking). The aggregate stability was influenced by method deployed and pre-selected classes of aggregate size. In this study, rainfall simulation (raindrop impact) and wet sieving (fast wetting) were the recommended methods to evaluate (sub) tropical soil aggregate stability. An aggregate size of 2–4 mm is preferable if a single class is selected.
  • Editor: Elsevier B.V
  • Idioma: Inglês
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  • Realização: ABCD-USP USP   Logos de Redes Sociais: Freepik

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