Physical, chemical and microbiological attributes of soils under different land uses in a toposequence in the northwest fluminense

Abstract

The objective of this study was to evaluate the interrelationships between land use, landscape position (position in a toposequence) and its effects on physical, chemical and microbiological attributes in soils under different land use systems in two toposequences in Northwest of Rio de Janeiro State. The toposequence 1 consisted of spontaneous vegetation in the summit and pupunha palm plantation in the backslope and footslope; Toposequence 2 consisted of pasture in the three positions. The following variables were determined: bulk density, total porosity and clay content; P, Ca, Mg, K, Al content and pH; microbial biomass carbon and nitrogen, microbial respiration, organic C and total N. Tocher method and principal component analysis (PCA) were performed for different groups of variables. Initially the physical attributes and some chemical attributes and then the microbiological attributes, organic C and total N were used. The groups formed by the Tocher method for the two sets of variables used were confirmed by the PCA. The set of physical and chemical attributes were more sensitive than COS, Nt and microbiological attributes to explain the similarity and, or, dissimilarity due to both toposequence positions and vegetal cover conversion. The microbiological attributes, COS and Nt showed the influence of vegetal cover conversion and management practices (and, or absence) in the dissimilarity between land use systems. The relevance of physical, chemical and, or, microbiological attributes to distinguish land use systems will depend on the variation sources of the environments in which these systems are being studied.