Atributos do solo e emissão de CO2 em Terra Preta Arqueológica preservada e sob cultivo em Novo Aripuanã, Amazonas, Brasil

Abstract

Changes in the composition of the vegetation of natural ecosystems, the use and management of soil, can have negative consequences on the ground, favoring the emergence of areas susceptible to physical degradation. In addition, there is the difficulty of finding information on the uses of Archaeological Dark Earth compared to environments under forest, specifically to evaluate possible changes in physical attributes and organic carbon, in addition to spatial variations of soil CO2 efflux. Thus, the aim of this study was to evaluate the physical properties, the organic carbon and the soil CO2 efflux in areas of Archaeological Dark Earth with different cover vegetation: guandu bean (Cajanus cajan), pasture (Brachiaria brizanta) and in native forest, using techniques of traditional univariate and multivariate statistics and geostatistics. Were delimited meshes sampling with regular spacing with 88 sampling points per mesh, and georeferenced. Soil samples and volumetric cylinders were collected in the layers 0.0-0.05 m, 0.05-0.10 m and 0.10-0.20 m for determination of physical properties and soil organic carbon. Assessments of soil CO2 efflux were performed using the LI-6400 systems in each sample point, and simultaneously were made measurements of soil temperature at 0-10 cm depth, using a thermometer portable thermistor, and soil moisture, using soil samples collected in the 0-10 cm layer. The results showed behavioral changes between environments with areas under guandu bean and pasture differ statistically with the area under forest, which showed stability aggregate characteristics above average, as well as structural characteristics, particle-size distribution and organic carbon below average. Soil CO2 efflux and soil temperature were lower in forest, with higher soil moisture. There was no statistical difference between the soil CO2 efflux and soil temperature under the guandu bean and pasture, but with lower soil moisture under pasture. By geostatistical analysis, soil properties showed standard behavioral changes of the spatial variability environments evaluated, analyzed in terms of the main components related to stability aggregate characteristics (PC1) and the structural characteristics, particle-size distribution and organic carbon (PC2).On the other hand, we observed changes in patterns of spatial variability of the soil CO2 efflux, soil temperature and soil moisture attributes, compared with the study areas. The adjustment models of semivariogram were spherical and exponential. The maps of the spatial distribution patterns indicate a tendency of concentration of the evaluated attributes.