**Abstract**

For sustainable production systems, the nonuse of fire (where there is a greater loss of soil nutrients), would be a solution for the conservation of nutrients in the soil, with the use of management by cutting and grinding, introduction of AFSs (agroforestry systems), and maintenance of riparian vegetation. The concentrations of carbon and nutrients were evaluated in the soil solution in two small hydrographic basins in the municipality of Igarapé-Açu (Pará state) in the eastern Amazon region, Brazil. The evaluations were performed considering the biogeochemical cycling in six land-use classes—riparian forest, secondary forest (*capoeira*), pasture, slash-and-burn agriculture, chop-and-mulch agriculture, and an agroforestry system (AFS). The objective was to determine the effects of different land-use systems on the composition of the soil solution, aiming to recommend sustainable practices. The concentrations of nutrients were greater in the areas of slash-and-burn agriculture and pasture, indicating greater losses of these nutrients due to runoff and leaching. The loss of nitrate was highest in the slash-and-burn area, while the organic carbon and organic nitrogen losses were greatest in the riparian forest, then in the secondary forest and agroforestry areas.

**Keywords:** Agrosystems, nutrient cycling, slash-and-burn, riparian forest soil solution extractor
