Qualidade do solo e dinâmica de crescimento de espécies florestais e frutíferas em sistemas agroflorestais sem queima na Amazônia.

Abstract

The natural conditions of low fertility and high acidity of the Amazon soils pose challenges for agricultural production in the region. In this context, soil organic matter (SOM) plays a key role by ensuring nutrient cycling and improving the fertility of tropical soils. The rational use of natural resources, such as the management of SOM, enables greater environmental and economic sustainability for the productive systems of the Amazon, treated here as part of a bioeconomy concept for the region. The objective of this study was to highlight the importance of SOM for agricultural production in the region and to evaluate the performance of an agroforestry system model implemented in recently deforested areas at the National Forest of Caxiuanã, State of Pará. In addition to the field experiment, in which the growth and mortality of twelve plant species were evaluated in three forest gaps, the work included a review article on the quality of soils in the Amazon and the advantages of using agroforestry systems (AFSs). After three years of monitoring the chemical attributes of the soils, a reduction in its fertility was observed, mainly related to the removal of the original vegetation cover. The evaluation of the arrangement of the species used in the AFSs of Caxiuanã revealed that species such as C. glandulosa, C. guianensis and O. bacaba are strongly recommended for planting in gap areas, while fruitful species such as M. paradisiaca, C. papaya and those of the genus Theobroma and Psidium should be inserted into the system only after improving its soil fertility. These results suggest, therefore, that the implementation of AFSs under these conditions should be carried out in two steps, using key species with the objective of improving soil fertility before the introduction of more nutrient demanding crops. As evidenced from the review, the choice of species, the arrangement used and the adoption of specific practices for managing SOM are important decisions to guarantee sustainable agroforestry production in the region.