Matéria orgânica e atributos físicos de Plintossolo Argilúvico Distrófico típico em diferentes agrossistemas na Amazônia maranhense

Abstract

The objective of this work was to evaluate the quality of organic matter and the physical attributes of a fragile soil under different uses of the Earth, aiming to establish a sustainable agrassystem proposal for replacement of conventional crops in the Amazon Maranhense. The experiment was conducted in four uses of soil: I) Secondary Forest (MS); II) conventional pasture (PC); (III) conventional farming (LC) and iv) agrotilvipastoril (SASP) system during the year 2019/2020, in the municipality of Pindaré Mirim, MA, Brazil. For physical evaluation of the soil, five minitrincheirs of 30x30x30 cm were opened in each use of the land, distributed of random liner, to collect tampered ties for macroporosity detention, microporosity, total porosity and soil density. Deformed composite sizes were also collected in each of the areas in the depths of 0-15 and 15-30 cm with the use of a Dutch tract, for analysis of total organic fractions - COT, part organic carbon - COP and organic carbon to minerals - COAM. The highest values of total macroposity and porosity was observed in the secondary forest, with 0,16 and 0,48 m3m-3, respecting, in depth 0-15 cm. The highest observed microporosidade values were in the agrotilvipastoril system (0,36 m3m-3) and pasture (0,36 m3m-3), in depth 0-15cm. A density revealed lower value in depth 0-15 cm in the woods (1,34 g cm-3) and greater value in pasture (1,53 g cm-3) in depth 15-30 cm. Enter as organic carbine fractions, the only compartment influenced by the uses of the Earth was the organic shit associated with the minerals, superior no agrotilvipastoril and in the forest in contrast to the smaller values in the conventional farming of maize. In depth, there was a decline in the levels and carbon stocks for all as analyzed fractions. Among the uses of the evaluated land, the agrosilvipastoril systems provided greater content of the most stable fraction of organic matter when comparing a conventional pasture. Larger coam levels were superior no agrotilvipostoril and in the forest in contrast a conventional farming of maize. Soil density and the coam have been shown to be more sensitive the density of changes caused by the different uses of the soil. The agrotilvipastoril system provided more stability of organic matter when compared to conventional systems. It is necessary for more evaluation time for identification if there is interference of agrosilvipastoris systems in the physical quality of the soil