Author(s)

R. S. León, A. A. Rodríguez & H. Santiago

Abstract

The objective of this experiment was to evaluate freshly cut (FCYT) and semidecomposed (SDYT) yard trimmings as bulking agents (BA) on the composting process of organic wastes from a commercial slaughter house (SHW). Treatments consisted in all combinations of BA (FCYT and SCYT), layers of SHW (none, single or double), and seven composting phases. Mixtures were weighted in a 2:1 proportion (BA:SHW) and placed in composting bins of identical dimensions (3 ft3). The moisture level was adjusted to 60% at the start of each composting phase. Temperature was recorded daily to determine the time (d) needed to reach the first and second heat cycles. Composting characteristics such as pH, C:N ratio, OM, IM, and N concentration were measured at 0 d, at the peak of the first and second heat cycles, and 0, 20, 40 and 60 d of maturation in the composting process. Data were analyzed using a 3 (layers of SHW) x 2 (BA) x 7 (composting phases) factorial design and ANOVA procedure of SAS. All treatments of FCYT/SHW and SDYT/SHW exhibited thermophillic temperatures after three days of composting. Regardless of treatment combination pH ranged from 7 to 8. Contents of OM and C were higher (P<.05), but IM was lower (P<.05) in FCYT than SDYT at all composting phases. At 60 d of maturation N and C:N values were not different. There was a decrease in OM and an increase in IM in all combinations of BA: SHW at all sampling times. At the end of the maturation phase, the C:N ratio was similar for none and single layers of SHW, but lower (P<.05) in double layers of SHW. In summary, FCYT and SDYT resulted in excellent BA for the composting of SHW. Further studies are needed to evaluate the use of this compost as an organic fertilizer. Keywords: composting, slaughterhouse wastes, bulking agents, yard trimmings.

Keywords

composting, slaughterhouse wastes, bulking agents, yard trimmings.