Pasture edaphic attributes in northwest region of Rio de Janeiro State, Brazil

Abstract

The aim of this study was to evaluate the seasonal variation of the attributes of soil quality indicators in areas of pasture planted with Brachiaria, Tifton 85 and Suazi in the municipality of Itaperuna, RJ, Brazil. The experimental design was completely randomized split plot with six replications. Soil samples were collected during the dry season (August 2004) and the rainy season (December 2004). These were evaluated in relation aggregate stability, using the mean weight diameter (MWD) and the proportion of stable aggregates (% AGRI) in water > 2.00 mm, the total organic carbon (TOC), the carbon from the humin fraction (C-HUM), carbon of humic acid fraction (C-FAH) and fulvic (C-FAF). In addition, samples were also collected for quantification of root dry matter (DM). The area with Brachiaria had higher MWD and % AGRI > 2.00 mm in the dry season, a pattern that is observed for Tifton 85 area, the rainy season. The highest TOC and C-HUM were found in area of Brachiaria in the two periods. The Tifton 85 had the lowest root of DM (10-30 cm). For the study conditions in the dry season, Brachiarias a cover plant more efficient to promote improvements in attributes (MWD, AGRI%> 2.00 mm and TOC) evaluated independente of the depth. For the rainy season, this pattern was observed for Tifton 85. The coverage of Brachiaria and Tifton 85 lead in higher root dry weight at a 10-30 cm soil depth compared with the coverage of Suazi, regardless of the season, demonstrating the potential of these grasses for use in projects of recovery of degraded areas.