Caracterização e gênese do caráter coeso em latossolos amarelos e argissolos da região dos tabuleiros costeiros do Estado de Alagoas

Abstract

The present work aimed at to characterize and to evaluate the possible formation mechanisms of cohesive horizons, in the soils of the Coastal Plain, searching to understand its genesis and to identify parameter that cans complement the definition of the cohesive character. For this, a profile of Yellow Argisol, Gray Argisol and two Yellow Latosol were collected and sampled cohesive and not cohesive horizonts. The samples were physics, chemistry, mineralogical and micromorphological analyzed. The presence of horizons with outstanding differences among the degrees of consistence of the dry and humid soil was verified, classified as cohesive horizons, observed so much in the areas under forests as in the areas under cultivation, being, therefore, considered of pedogenetic nature. The sílica and Aluminum contents, extracted with DCB and oxalate didn't presents high on cohesive horizons, suggesting that its genesis is not due to the presence of cementing agents. The morphology and soil density, allied to the determination of the specific surface area were shown efficient in the identification of the soils studied. The analyse resunts suggest that the cohesive horizon genesis presents two different phases, being its base initially formed by the illuviation of very fine clay, clogging the soil pores, happening later a loss of iron on the top, collapsing the structure, improving the face-toface the kaolinite adjustment.