ABSTRACT
Animal manure represents an important source of plant nutrients; however, it needs to be stabilized to avoid environmental contamination. These wastes, together with rice hulls, can be used in composting and vermicomposting and reinserted into the production system. In this study, compounds and vermicomposts were elaborated with rice hulls and poultry, bovine, and swine manure, which, after biological stabilization, were evaluated for chemical composition and fiber fractionation, associated to their suitability for agricultural use and potential fertilizer. The reduction in C content and C/N ratio with increase in the CTC/C ratio of the compounds and vermicomposts indicated that the processes boost the degradation of the organic residues and their stabilization. The manures affected the composition, with higher levels of P, Ca, and Mg in poultry waste materials (1, 4.9, and 1.6%, respectively). The compounds and vermicomposts presented similar composition, except for EC (reduction of 1.6 to 0.5 dS.m-1 in vermicompost in the average of the three wastes) and in K contents (reduction 1.8 to 0.6% in vermicompost with poultry waste), probably due to leaching during the process. There was a higher soluble fraction (61.5%) and lower cellulose (9.3%) and lignin (7.2%) contents in the compound and vermicompost with bovine manure, which could benefit the release of N to plants in the decomposition of this material. Compounds and vermicomposts could be used in sustainable production systems as a substitute for mineral fertilizers, and the amounts to be applied should be adjusted according to their specific composition.
Key words:
chemical analysis; fiber fractionation; recycling; sustainability