The understanding of the processes that cause the varied distribution of silica bodies in soils is essential for the interpretation of the possible environmental factors related to their stability, sediment deposition, paleosol formation and for the analysis of archaeological sites. Thus, this study had the objective of identifying and characterizing the silica bodies morphology from surface soil horizons collected at different terrestrial ecosystems. Samples of surface horizons were collected from 10 soil profiles and heated in a muffle furnace to […]

Most of the silicon absorbeb by plants remains deposited on the external part of the cell walls as a layer of amorphous silica (SiO2.nH2O), probably affecting straw mineralization in soils. An experiment was performed with the aerial part of oat plants, cultivated in nutrient solution with and without silicon addition, to evaluate this hypothesis. Dried aerial parts of oat plants tissue was mixed with soil or washed quartz sand and placed in PVC tubes. Distilled water was percolated through the […]

The semiquinone free radical concentration (SFRC), determined by electron paramagnetic resonance (EPR), is an index of degree of humification of soil organic matter. The objective of this study was to evaluate the possible interference of mineral fraction in the quantification of SFRC in organo-mineral aggregates 20-53, 2-20 and < 2 ∝m of three soils from southern Brazil: Paleudalf, Paleudult and Haplorthox. The SFRC was calculated by the semiquinone signal intensity (I, in cm) multiplied by its square line width (∆H2, […]