Humic fractions of soil carbon under agroforestry system in altitude swamp Pernambucano

MOS (soil organic matter) is a natural carbon reservoir, and divided into different stages of decomposition according to its solubility and structural complexity. In view of this context, this work aimed to quantify the carbon content in the humic fractions of the soil organic matter under an agroforestry system in three toposequences in the swamp of altitude in Pernambuco, Brazil. The study was carried out on the Yaguara farm, and the studied areas were native forest and three toposequences of agroforestry system. Soil samples were collected in trenches 1.5 x 1.5 m, at depths 0-20, 20-40 and 40-60 cm, with four replications. The carbon concentrations in the humic fractions of the soil decreased with increasing depth. The area with agroforestry system had the highest concentrations of carbon in the humic fractions. The stocks of humic fractions found in the agroforestry system area showed higher average values in the top area 5.62, 9.72 and 22.53 Mg ha-1 in relation to native forest 4.84, 8.28 and 19.20 Mg ha-1, respectively for fulvic acid, humic acid and humine. Among the evaluated areas, the soil with agroforestry system top area has great potential to increase the carbon storage in the humic fractions of the soil.