Estudo de três perfis de solos em pedoambiente de terra firme, Amaturá, Alto Solimões, Amazonas

Abstract

In the Alto Solimões region, in the state of Amazonas, pedological studies are still in their infancy. In the municipality of Amaturá, pedological information is minimal, which is worrying because soil use and management are recurrent, and it is known that the natural resource (soil) requires planning for appropriate management with the aim of conservation and sustainable use. With this in mind, we studied the genesis, the main physical and chemical attributes and classified the soils in the vicinity of the municipality of Amaturá, located in the Alto Solimões region, in the state of Amazonas, in order to propose appropriate use and management. Three soil profiles were opened and described in a terra firme area with an elevation of 76 to 68 metres. Samples of the pedogenetic horizons were then collected and conditioned in fine air-dried soil (TFSA), macerated and sieved, and the analyses were carried out: granulometric, aimed at separating and quantifying the sand, silt and clay fractions, chemical attributes were also analysed, such as active acidity (pH), exchangeable calcium (Ca2+), exchangeable magnesium (Mg2+), exchangeable potassium (K+), available phosphorus (P), exchangeable acidity (Al3+), potential acidity (H+ + Al3+) and organic matter (MO). Based on the results of the chemical analyses, the sum of bases (SB), cation exchange capacity (CEC), effective cation exchange capacity (t), percentage base saturation (V) and percentage aluminium saturation (m) were calculated. The three profiles were classified as typical Gleissolo Háplico Ta Alumínico endoredoxic, Argissolo Vermelho Tb Alumínico and typical Nitossolo Bruno Alumínico. The texture of the soils was silt and clay, with the Nitossolo dominating being very clayey. The morphology is marked in all three profiles, showing cracking when exposed to the sun, which is more pronounced in the typical Aluminaic Bruno Háplico Nitossolo. The three profiles were classified as dystrophic, with very low natural fertility, as indicated by the Ca2, Mg2 and P values studied, with a slight exception for Ca2+ in the Gleissolo profile, and K showed low to high levels. There was also identification of the Alum character in all the profiles studied, indicating very high levels of exchangeable aluminium, reaching 14.5 cmolc dm-3. The profiles can be limed and fertilised. These results will contribute to the management and use of the soils in the municipality of Amaturá, and represent a minimal contribution to pedological science in the Brazilian Amazon.