Carbon and soil microbial respiration in soil from conventional, organic vineyards and comparison with an adjacent forest

Resumo

This aim of this study was to examine the effects of vineyard management and spatial heterogeneity of soil on chemical and microbial variables in comparison with an adjacent forest fragment. In 2000, two field experiments with Vitis labrusca (L.) were set up on an Oxisol of North Paraná, Brazil. In 2004, soil samples were taken to evaluate the following factors: (i) conventional (CONV) and organic (ORG) vineyard management and (ii) spatial heterogeneity of soil, row or inter-rows cultivation and at different sampling depths (0-10 cm and 10-20 cm), in a split-plot arrangement fitted to a randomized complete block with six replicates. The forest adjacent fragment was considered as undisturbed agricultural (or control) area. Chemical attributes of the soil in the ORG vineyard were improved in comparison to the soil in the forest, at a depth of 0-10 cm, with the exception of total carbon. To microbial carbon (Cmic) values the both factors (vineyard management and special soil heterogeneity) contributed to changes in the contents this microbiological soil attributes in the areas evaluated. While, the spatial heterogeneity of the soil was the main factor to changes in soil microbial basal respiration, with higher values in the CONV rows. Regardless of the depth, the lowest qCO2 values were observed in the soil from the ORG vineyard and the forest. The cluster analysis showed that, represented on the Axis-X, the CONV vineyards, ORG vineyards and forest clustered from the negative to the positive, progressively, indicating greater similarity between ORG and forest. Moreover, when the spatial heterogeneity of the soil was plotted on the Axis-Y, the 0-10 cm layer appeared in the positive portion, and the 10-20 cm layer appeared in the negative portion. In the short term, it appears that different vineyard management methods affected microbial variables and some similarity between ORG and forest soil.