Fractions of organic matter in aggregates in archaeological black earth areas, Pará, Brazil
DOI:
https://doi.org/10.6008/CBPC2179-6858.2020.007.0002Keywords:
Quality of organic matter, Anthropic soils, Black Indian soilAbstract
Most of the Amazonian soils have low fertility, however discontinuous patches are observed where there are higher amounts of nutrients and high levels of total organic carbon (TOC), these areas being called archaeological black earth (TPA’s). Soil organic matter (MOS) is one of the most used indices to assess soil quality, which can be quantified by the COT present in humic substances (SH) and in the carbon determined through granulometric fractionation, being a greater protection of the COT as well as the MOS fractions observed in the aggregates. In this sense, the objective of this study was to evaluate the TOC content of the SHs and determined through the MOS granulometric fractionation in TPA's areas with different land uses. The samples were collected in the municipality of Santarém, Pará, in areas with different management methods and edaphic conditions, namely: (P1) cultivation of corn and cassava with intense agricultural use and without application of fertilizers; (P2) cassava cultivation, with a history of agricultural crops in succession for more than ten years; (P3) secondary forest area, located near the Tapajós River; (P4 and P5) fallow areas for more than six years with forages and (P6) with cowpea cultivation. Samples were collected at depths of 0.00-0.05; 0.05-0.10 and 0.10-0.20 m. In the aggregates, the contents of (COT), organic carbon of the SHs (fulvic acids - C-FAF, humic acids - C-FH and humine - C-FHUM) were determined and the physical particle size fractionation of the MOS (particulate fraction - COp and fraction associated with minerals - COam). The different uses of the soil did not compromise the levels of organic carbon associated with the fractions of organic matter of the TPA aggregates, being observed in the areas a high degree of similarity, and the area P1 presenting MOS values higher than the other areas.
Downloads
Downloads
Published
Issue
Section
License
The CBPC - Companhia Brasileira de Produção Científica (Brazil CNPJ: 11.221.422/0001-03) the material rights of the published works. The rights relate to the publication of the work anywhere in the world, including rights to renewals, expansions and dissemination of the contribution, as well as other subsidiary rights. All electronically published works may subsequently be published in printed collections under the coordination of this company and / or its partners. The authors preserve the copyright, but are not allowed to publish the contribution in another medium, printed or digital, in Portuguese or in translation.