CHARACTERISTICS OF STRAW COMPOSTING AND EVALUATION OF MATURITY IN CHENGDE,HEBEI PROVINCE

Composting is one of the means for treatment of solid organic waste,which makes the waste harmless and useful.In this study,A composting experiment was set up in the late autumn of 2009 in Chengde,Hebei province,using sunflower straws,corn stalks,soybean straws and chicken manure as raw materials,and adopting EM treatment.By measuring the temperature,moisture content,pH,NH+4-N,NO-3-N,C/N,T value in the composting process,the effect of material ratios on compost maturity was investigated.Chinese cabbage seed germination index(GI) was adopted to evaluate the maturity and physiological toxicity.The results showed that in the pile composting process,4 different treatments had significantly high temperature period.The chemical indicators and biological indicators changed regularly.At the end of the composting,NH+4-N content decreased to 1.0 g·kg-1,NO-3-N increased significantly,pH maintained at 7.6—8.1,C/N maintained at 14—18,T value was less than 0.6,and GI greater than 100%,all of which met the maturity standards for compost decomposition.F4 reached maturity first,followed by F2.On the GI index associated with each chemical analysis,GI was negatively correlated with NH+4-N,C/N,reaching-0.8999 and-0.6412 respectively,but had no significant correlation with NO-3-N.C/N was positively correlated with NH+4-N and NO-3-N,reaching 0.5821 and-0.5672 respectively.