Fracionamento e estoque de matéria orgânica em diferentes sistemas de manejo no solo no município de Igarapé-Açu, no nordeste do Pará.

Abstract

Knowledge of C stocks and their soil dynamics in land use systems is important in the development of technologies to establish sustainable systems, as well as to analyze the role of soil as a source or deposit of C-C02 in the atmosphere. The physical fractionation of organic matter is indicated to identify, in the short term, processes that are causing soil degradation. The objective of this work was to evaluate the carbon and nitrogen contents and to quantify the total carbon stock of the soil and those associated to the densimetric and granulometric fractions of organic matter in the soil. The soil was classified as Yellow Latosol, experimental arcas located in the communities of Cumaru (Crossbeam Cumaru), Nova Olinda (on the properties of small rural producers). The study was carried out in Bastem Amazônia, Northeast of Pará, in the municipality of Igarapé-Açu. ) and UFRA-FEIGA. The land use systems tested are TI CC (Cumaru Capoeira), T2 CSQT (Cumaru without crushed burning), T3 CQ (Cumam buming), T4 UFC (UFRA Capoeira), T5 UFSQT (UFRA without crushed buming), T6UFQ SAF 1 C (SAF Capoeira Plantio), SAF 1 PT (SAF planted crushed), SAF 2 C (SAF Capoeira) SAF 2 QP (SAF bumed and planted). Soil samples were collected at depths 0-5, 5-10 and 10-20 cm. The density (free and light occluded) and particle size (sand and silt + clay) fractions were determined for the determination of carbon contents by combustion in the FECO CHN-S TRUSTEC dementai analyzer. The studied variables were submitted to analysis of variance, compared by the Scott NK test. To obtain the results, the statistical program SISVAR (FERREIRA, 2007) was used. It was verified among the systems that the lower the carbon content, the lower the soil quality, the greater the risk of erosion and the loss of nutrients. Hence the importance of creating a system that can raise the carbon content of these soils, or use a system of land use that does not decrease the carbon content of the soil. The free light fraction concentrated more carbon on the surface. The contribution of the silt + clay fraction was highlighted in the concentration and total carbon stock.