Cocomposting - a method to improve results of poultry manure composting.

摘要

Composting of poultry manure (initial C:N ratio - 11.3) in a thermostatically aerated pile resulted with overheating (>65 deg C) and rapid loss of Total Volatile Solids (TVS) and of nitrogen. Adding 5% (on a dry weight basis) of squeezed grapefruit peels (initial C:N ratio of the mixture - 12.4) lowered the pH of the aqueous phase of the raw materials from 6.6 to 5.8 (in a 1:10 extract). This enabled controlling the pile temperature below 60 deg C and increased the amount of conserved N by～80%. Nitrogenwas conserved more than the TVS on a relative basis in this mixture but conserved less than the TVS in the poultry manure alone. This suggests that previously released NH4+ was biologically immobilized in the mixture. Although the effect of the added acidic carbon source was apparent until the end of the composting period on the above mentioned parameters, a sharp rise in pH and a decline in C:N ratio occurred after <12 and <39 days, respectively. This suggests that adding more squeezed grapefruit during the composting period may have caused additional beneficial effect on the characteristics of the end product.