The levels of organic matter and aluminum and the pH of the predominant soils in the North and Northwest regions of Rio de Janeiro State were studied during the dry (June-July) and rainy (December-January) seasons of the year. Samples of soil were collected from 12 different places of the regions, in predominant grazing areas, as determined by satellite photography and according to different soil characteristics. The aluminum contents of the sample extracts were determined by spectrometry, on an inductive plasma emission source apparatus. Organic matter levels in the soils samples were not affected by season of year; presented very low in all sampling places and always below 3%. Aluminum was not detected in some places and in other places the levels were very low. Negative correlation was found among aluminum levels and soil pH (r = - 0.85, P = 0.0002). Except for two places, the soils were considered acids with the pH changing in function of places, without season effect.
mineral; pasture; pH; soil
