An Index System for Evaluating the Maturity of Animal Manure Composting

Under aerobic conditions in a climate chamber, high temperature composting of dairy and swine manures with crop straws were studied to determine the variation of maturity indexes of the composting, including physical, chemical and biological indexes.The results indicated that:the temperature rosed rapidly, and lasted for more than 15 d over 50 ℃;the pH values had a rise followed by a drop, and stayed stable at around 8.0 after 60 d;the moisture and C/N ratio dropped, and the C/N ratio was close to 20 after 60 d;the NH3-N content had experienced from increase to decrease, while the HA/FA ratio was opposite, from decrease to increase;the Solvita maturity degree, germination index and root establishment index all increased during the composting;the growth index had no significant change.The correlation analysis among maturity indexes showed that, the Solvita maturity degree, which was the best representative of composting maturity, was highly correlated with C/N ratio, GI, root establishment index, and slightly correlated with moisture and humic acids.Therefore, the index system for evaluating the maturity of animal manure composting was established together with the regular index of temperature based on the results from this study.