Qualidade física, carbono orgânico e estoques de carbono em pastagens no sul do Amazonas

Abstract

The Amazon biome has an enormous biodiversity, but in recent years it has been suffering from the advance of anthropic activities, mostly in an erroneous way and without proper care, one of which is agriculture, with the replacement of native forests by pasture areas for of livestock production, therefore, studying the soil-plant relationship is fundamental for understanding the impacts caused by these managements. In view of this, there is a need for studies that evaluate areas with pasture, identifying the effect of cultivation on the physical attributes and organic carbon of the soil in areas under recurrent management of livestock activities. The study areas are located in the municipality of Humaitá, in the south of the state of Amazonas. In the field, five (05) pasture areas, one (01) natural field area and one (01) forest area were selected, in each area a transect was made with fifteen (15) sample points, in each of these places were open mini-trenches for soil collection (deformed and undeformed sample) in layers of 0-10 and 10-20 cm. The soil collected in clods was dried in the shade and subsequently crushed to obtain aggregates and air-dried fine earth, the volumetric rings (undeformed sample) were saturated on the tension table and finally taken to the penetrograph, thus determining the attributes in the laboratory. : sand, silt, clay, macroporosity, microporosity, total porosity, DMG, DMP, aggregate stability index, gravimetric moisture, soil density, soil resistance to penetration, organic carbon and soil carbon stock. After obtaining the data, these were tabulated and analyzed using descriptive statistics, test of means to compare the environments, correlation analysis and finally the analysis of principal components by multivariate. Conversion of forest to pasture negatively impacted aggregates >2 mm, soil density, concentration and soil organic carbon stock, as well as soil resistance to penetration, gravimetric moisture, total porosity and soil macroporosity. Organic carbon is positively correlated with aggregates >2 mm, geometric mean diameter, weighted mean diameter, and negatively correlated with soil density. Aggregate stability influences carbon sequestration in the studied pasture and forest areas, but does not influence the natural grassland environment