Cocomposting - A method to improve results of poultry manure composting

Composting of poultry manure (initial C:N ratio -11.3) in a thermostaticall y aerated pile resulted with overheating (>65 degrees C) and rapid loss of Total Volatile Solids (TVS) and of nitrogen. Adding five percent (on a dry weight basis) of squeezed grapefruit peels (initial C:N ratio of the mixtur e -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 b elow 60 degrees C and increased the amount of conserved N by ca. 80 percent . Nitrogen was conserved more than the TVS on a relative basis in this mixt ure but conserved less than the TVS in the poultry manure alone. This sugge sts that previously released NH4+ was biologically immobilized in the mixtu re. Although the effect of the added acidic carbon source was apparent unti l the end of the composting period on the above mentioned parameters, a sha rp rise in pH and a decline in C:N ratio occurred after less than 12 days a nd less than 39 days, respectively. This suggests that adding more squeezed grapefruit during the composting period may have caused additional benefic ial effect on the characteristics of the end product.