Caracterização Física e Química de dois perfis de solos em Santo Antônio do Içá, Alto Solimões, Amazonas

Abstract

The Amazon region is a stable geological area that stretches from Roraima to the Central Plateau and has rocks of different ages. The Içá, Alter do Chão, Boa Vista and Solimões sedimentary formations stand out, each with unique properties. The main objective of this study is to understand the genesis and characterisation of two soil profiles in the municipality of Santo Antônio do Içá - AM. The study area is located in Alto Solimões, in the municipality of Santo Antônio do Içá, in the Içá river sub-basin, on the left bank of the Solimões river, belonging to the Içá formation. Areas representative of the local geomorphology were selected, observing toposequences for the choice of pedoenvironments, where trenches were opened for morphological description and sample collection. The samples of air-dried fine soil (TFSA) were analysed to determine pH in water, Ca2+, Mg2+ content by atomic absorption spectrometry and Al3+ using a 1 mol L-1 KCl solution, and K+ content by extraction with a Mehlich-1 solution (0.05 mol L-1 HCl + 0.0125 mol L-1 H2SO4). Total acidity was assessed by extraction with 0.5 mol L-1 calcium acetate at pH 7.0, and quantification with 0.05 mol L-1 NaOH. Based on the analytical results, parameters such as base sum (SB), cation exchange capacity (CEC) at pH 7 (T), effective CEC (t), base saturation (V%) and Al3+ saturation (m%) were calculated. Available phosphorus was quantified by colorimetry with ascorbic acid after extraction with Mehlich-1 solution. Organic matter was calculated using a conversion factor of 1.724. Two trenches were opened in different locations. The first is located on Estrada do Aeroporto, coordinates (3°04'28.9‘S, 67°58'31’W), on a gently undulating terrain, currently used as pasture, and is classified as Typic Dystrophic Yellow Latosol. The second trench, identified as plinthosolic argissolic Yellow Dystrophic Latosol, is located in the Lázaro Martins Branch, coordinates (3°4'6.31‘S, 67°57'51.70’O), also on gently undulating terrain and currently used as a farm. Thus, we have Profile 01 (P01) and Profile 02 (P02). The research data will be useful to farmers in Santo Antônio do Içá-AM. They will contribute to proper soil management, enabling good agricultural production. A thorough understanding of soil properties will enable producers to make fundamental decisions regarding crops, fertilisers and conservation practices, since soil use and management are crucial factors for environmental sustainability.