Chemical attributes and soil carbon and nitrogen stocks in pastures in the Maranhão Amazon

Abstract

In the eastern Amazon region, converting forests into pastureland is a common practice that quickly leads to the degradation of these areas. This study aimed to evaluate the influence of different land uses in different evaluation periods on the chemical attributes, total contents, and carbon and nitrogen stocks of the soil in the Maranhão Amazon. The land use systems analyzed were: perennial pasture (PP), recovered pasture (RP), and secondary forest (SF). Trenches were opened in 2013 and 2019 in each use system in the 0.0-0.20 m and 0.20-0.40 m soil layers. The soil chemical attributes (pH, P, K, Ca, and Mg) and C and N contents and stocks were assessed. PP in the surface layer showed superior results compared to RP and SF, while the opposite behavior occurred in the subsurface. The chemical attributes of the soil decreased over the years evaluated, regardless of the layer and area. The chemical attributes of the soil, as well as the C and N contents and stocks, changed depending on the land use, layer, and year of sampling.