Evaluation of physicochemical attributes of a yellow latosol under agroforestry system as compared to secondary forest in the Eastern Amazon

Abstract

In Brazil, the productive and sustainable use of Amazonian soils under agroforestry systems (AFS) has been considered a research challenge. This study aimed to evaluate the physicochemical attributes of a soil under AFS, comparing it with the soil under an adjacent secondary forest (SF). The study was carried out in an AFS area cultivated with passion fruit (Passiflora edulis), cupuacu (Theobroma grandiflorum) and Brazilian mahogany (Swietenia macrophylla), between 2005 and 2019. Both study areas (AFS and SF) were divided into five blocks. Sampling was carried out in two soil depths (0–20 cm and 20–40 cm), which was subjected to chemical analysis to determine the pH in water, contents of macro- and micronutrients, exchangeable bases, exchangeable aluminum, base saturation, cation exchange capacity and organic matter contents. As for the physical attributes, penetration resistance (PR) up to 40 cm deep in the soil was evaluated, using 50 randomized measurement per study area. The contents of macronutrients were higher in AFS, and the content of organic matter was higher in SF. The contents of micronutrients did not follow a specific pattern, and presented a similar distribution in both environments. The PR was higher in SF, showing a linear behavior that increases with increasing depths, while in AFS, there was a stabilization tendency within soil depth. Soil fertility was better in AFS, mainly due to the residual contents of periodic fertilization, in addition to presenting better conditions for root establishment.