Estudo da fauna edáfica na vermicompostagem de resíduos orgânicos

Abstract

The objective of this work was to study the edaphic fauna occurring in the vermicompost process of the residues of herb-checkmate, coffee drag, bovine, equine and ovine manure, as well as to analyze chemically and physically these materials. These substrates were stored in 10 liter plastic plots in horizontal laboratory benches, using a completely randomized design with five replications, where, after a stabilization period, 150 California worms (Eisenia foetida) in each treatment. As a tool for data analysis, the statistical software DivEs® were used to calculate the ecological indexes of diversity, dominance, equitability and species richness, used for analysis of the edaphic mesofauna. In this study different evaluations were made such as: macronutrients, C/N ratio, organic carbon, pH, density, humidity, counting of the edaphic mesofauna (mites and collembolans), macrofauna (worms and cocoons) and microorganisms (total fungi, cellulose-degrading bacteria and diazotrophic bacteria) and microbial respiration. The residues studied presented different results among themselves. It was verified a numerical superiority of the edaphic mesofauna in the vegetal residues when compared with the ones of animal origin, being a predominance of collembolans in all the evaluated treatments (n = 121864). With regard to macrofauna, a larger number of cocoons (n = 323) and earthworms (n = 236) were observed at the end of the vermicompost process in ovine manure. During the execution of the experiment it was noticed that only in the bovine manure treatment there was a decrease in the development of cellulose degrading bacteria (from 6.6 x 1011 to 2.3 x 109 ), already for the diazotrophic bacteria, only in the treatment equine manure occurred an increase in its population (from 6.0 x 103 to 9.5 x 107 ). Total fungi maintained a homogeneous distribution throughout the evaluations in all the experimental units. In all the samples there was a reduction of the microbial respiration during the vermicompost process due to the maturation of the organic residues. It was observed a decrease in the C/N ratio, with emphasis on the vegetable residues that presented the highest values of the same, however, in these residues were verified the lowest concentrations of the macronutrients P, K and Mg. With the exception of equine manure, the pH adjusted to values recommended at the end of the experiment on all substrates. The ecological indexes of diversity and equitability showed a predominance of organisms in ovine manure. Considering the results obtained in this study, we can suggest the use of these residues for vermicomposting, and recommend the use of their vermicompost as an organic fertilizer with the precautions.