Atividade microbiana de um argissolo vermelho-amarelo sob bosque de sabiá (Mimosa caesalpiniifolia Benth)

Abstract

The biochemical attributes of the soil such as: the respiration rate, readily mineralizablecarbon, carbon from the microbial biomass and its activity as well as its metabolic quotient,microbial C/total organic C ratio are indicators that provide fundamental information on the maintenance and productivity of ecosystems. The objective of this study was to evaluate the microbial activity of the soil of a Red-Yellow Argisol under a thrush forest (Mimosa caesalpiniifolia Benth) implanted in 1999, occupying an area of approximately 5,000 m2 And a total of 1670 plants. Four collections were made over the course of a year. Soil microbial respiration was determined by capturing the evolved CO2 followed by titration in HCl. The determination of biomass carbon was carried out using the fumigation-extraction and oxidation method of organic carbon by potassium dichromate (K2Cr2O7). From the results of basal respiration of soil samples and the microbial biomass C, the metabolic quotient (qCO2) that represents the amount of C-CO2 evolved per unit of microbial C (μgC-CO2/hour– 1 /μgC-biomass.g-1 dry soil). Through analysis of variance for soil microbial activity, it was possible to detect statistically significant differences (Tukey p<0.05). Thus, the analyzes show that there are differences between the collections from collection 3, which is the same as collection 4, as well as collections 1 and 2 not the same and different from the others. The analysis of variance for the carbon release data detected, between collections, the accumulated average of evolved CO2 was approximately 420 to 520 mgCO2kg- 1. Regarding the CMB, it was detected through ANOVA that there was no significant difference (p<0.05) between the collections, even though they show increasing values over time. Like CBM, total organic C did not show statistically significant differences (p<0.05) through ANOVA. The microbial quotient and the metabolic quotient showed statistically significant differences. It was concluded that, In this work, the metabolic activity of microorganisms indicates that the soil is close to the equilibrium state.