We have imaged the particles of Brazilian soils at multiple length scales, from a few microns to millimeters, and soil particle size distributions were calculated with unmatched precision. The analysis included the Amazonian soil "Terra Mulata de Índio" (TMI), an anthropogenic soil (Anthrosol) with sustained fertility and a large amount of stabilized organic matter. Firstly, the soils were imaged ex situ, without any chemical processing, with sequential electron scanning of the pelletized soil samples, covering a total area of 8 × 8 mm. Secondly, it was performed a computational analysis of the large-field X-ray images assembled from hundreds of adjacent elemental maps, thus resulting in high-definition images (4800 × 4800 pixels). This analytical approach provides a large sampling with the identification of > 10,000 particles over the scanned area. The particles identified consisted of Al, C, Ca, Cr, F, Fe, Mg, Mn, Na, O, P, S, Si and Ti. A significantly larger concentration of C-, Ca-and P-based particles, of up to 100 μm 2 of cross-section area, was found in TMI samples in comparison with oxisol and ultisol soils. While the mean distance between neighboring C, Ca and P particles in TMI was of 40-70 μm, the value was of hundreds of microns in oxisol and ultisol. Furthermore, mapping of micrometric carbon particles by Raman spectroscopy indicated that they have a graphitic structure with a large amount of defects, partially associated with particle oxidation, although a well-preserved sp 2 graphitic structure is also present. From a technological perspective, improved soil amendments, such as biochar, can be rationally designed from the "fingerprint" described here for soil particles of Amazonian Anthrosols (i.e., morphological and structural characteristics), which can result in an increase in fertility and the optimization of carbon sequestration in the future.
NUTRIENT AND ORGANIC CARBON RELEASE IN SOILS CONTAINING WASHED AND NOT WASHED HYDROCHAR COMPARED TO ANTHROPOGENIC SOILS. Hydrochar washed (1.0, 2.5, 5.0 and 10.0 %) and not washed (10.0%) produced by hydrothermal carbonization using vinasse and sugarcane bagasse was applied in sand, ultisol and oxisol columns, and the release of NO 3 -, Orthophosphate, SO 4 2-, Total Organic Carbon (TOC), H + were evaluated for 30 days. These results were compared with the release of these parameters from experiments conducted with anthropogenic soils. The results demonstrated that higher amounts of nutrients were released for the experiments conducted with hydrochar not washed. With higher rates of hydrochar washed, higher the amount of nutrients released. TOC and SO 4 2were released throughout the experiment, which is beneficial from the agricultural point of view. Low values of orthophosphate and nitrate release in the leachates were observed for ultisol and oxisol due to the clay and iron and manganese oxides contents. Principal components analysis confirmed the observations and demonstrated that SO 4 2and TOC preferentially influence the oxisol, being that nitrate and pH influenced the columns containing Terra Mulata and sand. The results allow to conclude that it is possible to adjust the application rate of hydrochar in soils with lower fertility in order to increase it as observed for anthropogenic soils.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.