Variabilidade espacial de carbono orgânico do solo em áreas de floresta nativa e sistema agroflorestal no Médio Amazonas

Abstract

The intensified emission of greenhouse gases (GHG) triggered by inadequate soil management and use has resulted in drastic climate changes and can lead to scarcity of natural resources, making human subsistence difficult. In this parameter, the implementation of agroforestry systems (SAF's) are highlighted as mitigating disturbances arising from GHG. Thus, the present work aims to determine the soil organic carbon content and to evaluate the effect of land use and management conversion on the soil's ability to store organic carbon, as well as to verify the spatial variability of soil density and carbon stock in the middle Amazon region. The study was carried out in the municipality of Silves-AM, with field sampling in an AFS area and a native forest (FN), at three depths, 0-10, 10-20 and 20-40 cm, in sample meshes and regular spacing. Soil bulk density (Ds) was determined by the volumetric ring method and CO by the wet oxidation method, estimating EC values from CO and Ds for all layers. Geostatistical analyzes were performed with the creation of maps for each analyzed factor, using semivarigrams. To compare the areas, the Mann-Whitney test was applied at 5% significance level. The SAF area had lower Ds with respective values of 1.20 g.cm-³, 1.41 g.cm-³ and 1.40 g.cm-³, for depths 0-10 cm, 10-20 cm and 20-40 cm, while in NF the Ds was 1.42 g.cm-³, 1.51 g.cm-³ and 1.52 g.cm-³. The two environments are statistically similar for CO contents at the three depths. The EC was higher in the NF in all layers, being similar to the SAF only in the depth of 10-20 cm. The semivariograms and kriging maps demonstrated the spatial variability between the Ds and EC attribute points. It was concluded that the AFS showed efficiency, being promising for carbon storage, considering that the lowest EC results of this system are due to the lowest Ds. The highest EC and CO and lowest Ds values were found at the surface depth of both environments. The use of kriging to generate maps is advantageous for soil studies with greater detail and accuracy of the behavior of the analyzed attributes.