MICROBIAL ACTIVITY AND ORGANIC MATTER OF LIGHT AREAS WITH DIFFERENT STAGES IN SEMI-ARID SUCCESSIONAL PARAIBA

The aim of this study was to evaluate the microbial activity and the contribution of light organic matter (LOM) in areas under natural regeneration of the Caatinga, checking the effect of seasonality and turn (daytime and nighttime) about the the release of CO2 from the soil. The experiment was conducted in the municipality of Santa Terezinha, ParaIba, where four areas were selected: (1) pasture (P), (2) Early Stage (E) of natural regeneration in the last five years, (3) Intermediate Stage (I) regenerating the last 15 years, and (4) Late Stage (L) of approximately 50 years. Microbial activity was determined in the field, monthly in two turns (daytime and nighttime). Respiratory activity in the soil was low in all areas and periods evaluated, with the lowest values for the areas of P and L. The CO2 values tended to be higher in the rainy season when compared to the dry season. The content of LOM was higher in P and E, in the dry season, and did not differ statistically between the areas during the rainy season. All attributes have tended to be influenced by temperature and soil moisture.