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Generally, TOC-contents are lower than 30 g kg -1 in the surface layer in most soils of the Brazilian Amazon Lima et al.
Chemical properties In all samples the soil pH H2O varied from lied. A number of soil morphological horizon denomination and thickness, Munsell color and physical properties particle size distribution, bulk density and total porosity were also studied, using methods described by Santos et al.
The cationic nutrient contents were rather low in all soil profiles Table 2i. The minerals were interpreted from the difractograms, as proposed by Chen The lowest values were observed for P4, especially in the B 1 and B 2 horizons, suggesting low water drainage capacity of this soil.
In the Central Amazon, soil profiles with ferruginous materials i. The profile classification and soil morphological and physical properties are given in table 1. In contrast, the total iron oxide contents found in the ferruginous materials were higher than g kg -1revealing a high concentration of Fe-oxides in these ferruginous concretions, formed after a period of time of wetting and drying processes in these soil systems.
Based on these pH values, the profiles can be classified as strong to moderate acidic Embrapa, Keys to soil taxonomy. Geological survey occasional paper, This work was carried out to investigate the chemical behavior, mineralogical composition and weathering stage of four representative soil profiles with plinthite and petroplinthite, in Iranduba, AM Central Amazon.
In the Central Amazon, these soils represent around 7. The clay material was separated by sedimentation pipette method. How to cite this article. Morphological and physical properties. Ntida diferena entre horizontes A e BT. In all soils, total porosity TP increased in the deeper layers, indicating an opposite tendency to that of soil bulk density.
In general, total organic carbon TOC contents are higher in the top layers, decreasing with depth Table 2. In general, soils with Ki index lower than 2. Other components such as gibbsite, kaolinite and 2: The sand particles were separated by sieving and crushed afterwards in an agate mortar. Plinthosols are composed of mineral material with either a plinthic or a petroplinthic horizon 50 cm below the soil surface, or a plinthic horizon cm deep, when underlying either an albic horizon or a horizon with stagnic properties Embrapa, ; IUSS Working Group WRB, The bulk density ranged from 1.
According to the Brazilian System of Soil Classification – SiBCS Embrapa,the genesis of Plinthosols and other soil classes with plinthite or petroplinthite is related to alternating wetting and drying cycles over long time periods. Iron oxides such as goethite and hematite are the major constituents of the ferruginous materials, e.
Plinthite is a soft, humus-poor and pedologi material composed of clay minerals, with quartz, aluminum and other materials Embrapa, ; Soil Survey Staff, The objective of this research was to investigate the chemical behavior, mineralogical composition and weathering stage of four representative soil profiles with ferruginous materials in the Central Amazon, Iranduba AM. The cation exchange capacity CEC of the well-drained soil profiles P1, P2, and P3 was very low, as also observed in the topsoil of the poorly-drained P4, where however the CEC values increased in the deeper layers Table 2.
In turn, the poorly-drained P4 show a different stage of development, basically due to the presence of 2: In all samples the soil pH H2O varied from 4. Carter sdico ou soldico na parte Subsuperficial. The lowest Fe d amounts were found in P4.
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X-ray diffraction and the identification and analysis of clay minerals. The lowest and highest values were found peeologia P4 and P3, respectively. London, Mineralogical Society,