Atributos morfológicos, físicos e químicos de Latossolos Amarelos, em Santo Antônio do Içá, Alto Solimões, Amazonas

Abstract

In the municipality of Santo Antônio do Içá, pedological studies are limited, but land use is common among rural producers, namely family farming and incipient livestock farming. In order to provide pedological information, we studied the genesis and physical-chemical attributes of soils in the municipality of Santo António do Içá, Amazonas. Two soil profiles were opened and described in areas with elevations ranging from 85 to 88 metres, respectively. Samples of the pedogenetic horizons were then collected and air-dried, macerated and sieved (TFSA). The physical attributes of these samples were assessed, namely: particle size analysis, aimed at separating and quantifying the coarse and fine sand, silt and clay fractions; and chemical attributes, 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 of base saturation (V) and percentage of aluminium saturation (m) were calculated. The two profiles were classified as typical dystrophic yellow loam and dystrophic argissolic yellow loam. Their chemical attributes are similar and their morphology is marked by charcoal fragments in the surface horizons. Subangular block structures predominate, they are well drained, have generalised chemical poverty, for Ca, Mg, P, only K showed medium and high levels. They are highly dystrophic and are considered oligotrophic (V% less than 25). Both can be limed and fertilised. Profile P02 has a retractable character (cracking). These results will contribute to the management and use of the soils of Santo Antônio do Içá, and represent a minimal contribution to pedological science in the Brazilian Amazon.