Effects of heating on soil physical properties by using realistic peak temperature gradients

Thomaz, Edivaldo Lopes; Fachin, Paulo Ângelo

doi:10.1016/j.geoderma.2014.04.025

Cited by 31 publications

(23 citation statements)

References 30 publications

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“…The direct and indirect effects of fire were often studied in soil surface (e.g., Arocena and Opio, 2003;Huseyin, 2006;Thomaz and Fachin, 2014;Meira-Castro et al, 2015;Armas-Herrera et al, 2016;Aznar et al, 2016), but some works showed that these effects reach deeper soil layers, at least down to 30 cm (Fonseca et al, 2011;Dennis et al, 2013;Heydari et al, 2017). The present work is in agreement with the results presented by the former authors, contributing to reinforce the idea that more attention should be given to the direct and indirect effects of fire at deeper depths.…”

Section: Depthsupporting

confidence: 91%

Effect of prescribed fire on soil properties and soil erosion in a Mediterranean mountain area

et al. 2017

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Section: Depthsupporting

confidence: 91%

Effect of prescribed fire on soil properties and soil erosion in a Mediterranean mountain area

et al. 2017

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“…The effects of high severity fires vary from disaggregation as a consequence of the OM loss, to strong aggregation, if a recrystallization of minerals such as Fe‐ and Al‐oxyhydroxides occurs after exposure to high temperatures. Thomaz and Fachin () report a threshold at 550°C in a laboratory study, where a sharp change in aggregate stability and diameter occurred. At temperatures between 250°C and 550°C, they observed OM depletion associated with a decrease in aggregate stability.…”

Section: Stability and Turnover Of Microaggregatesmentioning

confidence: 99%

“…The effects of high severity fires vary from disaggregation as a consequence of the OM loss, to strong aggregation, if a recrystallization of minerals such as Fe-and Al-oxyhydroxides occurs after exposure to high temperatures. Thomaz and Fachin (2014) Accounts of methods that directly measure the turnover of aggregates are rare. An interesting approach has been developed by De Gryze et al (2006), which relies on the use of tracer compounds foreign to soils, like rare earth oxides.…”

Section: Microaggregate Formation By Physical Processesmentioning

confidence: 99%

Microaggregates in soils

Totsche

Amelung

Gerzabek

et al. 2017

J. Plant Nutr. Soil Sci.

610

415

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All soils harbor microaggregates, i.e., compound soil structures smaller than 250 μm. These microaggregates are composed of diverse mineral, organic and biotic materials that are bound together during pedogenesis by various physical, chemical and biological processes. Consequently, microaggregates can withstand strong mechanical and physicochemical stresses and survive slaking in water, allowing them to persist in soils for several decades. Together with the physiochemical heterogeneity of their surfaces, the three-dimensional structure of microaggregates provides a large variety of ecological niches that contribute to the vast biological diversity found in soils. As reported for larger aggregate units, microaggregates are composed of smaller building units that become more complex with increasing size. In this context, organo-mineral associations can be considered structural units of soil aggregates and as nanoparticulate fractions of the microaggregates themselves. The mineral phases considered to be the most important as microaggregate forming materials are the clay minerals and Fe-and Al-(hydr)oxides. Within microaggregates, minerals are bound together primarily by physicochemical and chemical interactions involving cementing and gluing agents. The former comprise, among others, carbonates and the short-range ordered phases of Fe, Mn, and Al. The latter comprise organic materials of diverse origin and probably involve macromolecules and macromolecular mixtures. Work on microaggregate structure and development has largely focused on organic matter stability and turnover. However, little is known concerning the role microaggregates play in the fate of elements like Si, Fe, Al, P, and S. More recently, the role of microaggregates in the formation of microhabitats and the biogeography and diversity of microbial communities has been investigated. Little is known regarding how microaggregates and their properties change in time, which strongly limits our understanding of micro-scale soil structure dynamics. Similarly, only limited information is available on the mechanical stability of microaggregates, while essentially nothing is known about the flow and transport of fluids and solutes within the micro-and nanoporous microaggregate systems. Any quantitative approaches being developed for the modeling of formation, structure and properties of microaggregates are, therefore, in their infancy. We respond to the growing awareness of the importance of microaggregates for the structure, properties and functions of soils by reviewing what is currently known about the formation, composition and turnover of microaggregates. We aim to provide a better understanding of their role in soil function, and to present the major unknowns in current microaggregate research. We propose a harmonized concept for aggregates in soils that explicitly considers the structure and build-up of microaggregates and the role of organo-mineral associations. We call for experiments, studies and modeling endeavors that will link informatio...

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“…In a previous study, we observed no effect of fire on soil organic depletion at topsoil, that is, 2.5 cm at depth . In contrast, we observed, in a laboratory experiment, that a temperature of 250 °C lasting 15 min was enough to reduce OM (Thomaz and Fachin, 2014). However, field experiments are complex, and many variables cannot be controlled properly (e.g., fire intensity, soil moisture, soil texture, etc.).…”

Section: Fire Temperature Effects On Organic Matter and Aggregate Stamentioning

confidence: 78%

“…An increase in aggregate stability was observed when the temperature increased from high (550 °C) to very high (650 °C), in spite of soil carbon reduction (Thomaz and Fachin, 2014). Overall, the slash-and-burn system displayed immediate effects on some soil physical properties .…”

Section: Fire Temperature Effects On Organic Matter and Aggregate Stamentioning

confidence: 96%

High fire temperature changes soil aggregate stability in slash-and-burn agricultural systems

Thomaz¹

2017

Sci. agric. (Piracicaba, Braz.)

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Fire is a key controlling factor in ecosystem dynamics worldwide, especially, in tropical areas under slash-and-burn agricultural systems. Farmers use fire as a tool to clean the land, and benefit from nutrient enrichment from ash-soil heating. However, fire can cause some detrimental effects on soil systems, such as organic carbon depletion, increased soil erodibility, and changes to aggregate stability. In this study, an experimental fire was applied to a plot of land following the local traditional practice of slash-and-burn. The fire temperature was monitored in the field, and its effect on soil aggregate stability was assessed. The fire temperature on soil surface was measured in four trenches, and it ranged from 355 to 660 °C (average 484 ± 142 °C). The fire temperature did not affect soil organic matter content. However, aggregate stability increased by 10 % in comparison to unburned soil. Moreover, the geometric mean diameter of burned soil was 20 % higher than that of unburned soil. In conclusion, high fire temperature changes soil aggregate stability in slash-and-burn agricultural systems.

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Effects of heating on soil physical properties by using realistic peak temperature gradients

Cited by 31 publications

References 30 publications

Effect of prescribed fire on soil properties and soil erosion in a Mediterranean mountain area

Effect of prescribed fire on soil properties and soil erosion in a Mediterranean mountain area

Microaggregates in soils

High fire temperature changes soil aggregate stability in slash-and-burn agricultural systems

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