Vermicomposting Of Rural Waste And Characteristics Of Greenhouse Gas Emissions

The organic wastes consisted of livestock manure, crop residues and leaves account for a considerable proportion of agriculture waste. The environmental pollution caused by stockpiling of these rural wastes has become an urgent problem. It is recognized as a better approach to treat the organic wastes with earthworm. Vermicomposting is the combination of the traditional compost and the earthworm treatment. With the metabolism of earthworm, the organic wastes will be changed into earthworm excrement with the best physical, chemical and biological characteristics.Because the initial condition of fresh manure does not suit earthworm's reproduction and the earthworm also can not endure the high temperature which produces in the composting, the organic wastes consisted of livestock manure, crop residues and leaves should be pre-composted first and then vermicomposted.In this paper, cow dung, corn stalks, wheat straw and leaves are choosed as experimental materials. The mixture consisited of different materials applied to vermicomposting are ascertained, and the changes of parameters are also studied during the composting. Besides, the characteristics of greenhouse gas emissions are measured during the composting. The research indicated that,(1) 8 groups of mixtures with different ratio were pre-composted for 39 days. After composting, the C/N of mixture dropped to below 25 from initially 35. The contents of organic matter were also decreased. The total nitrogen increased to above 1.11%(wt%) from initially 1%(wt%). The contents of ammonian increased first and then decreased during the treatment, finally between 200 mg/kg and 300 mg/kg.(2) The mixtures of 8 groups were inoculated with earthworms for 30 days after composting. The earthworms all died in the mixtures contained wheat straws after 11 days. The survival rates of earthworms were 0. The survival rates of earthworms were above 62.5% in the mixtures contained Corn stalks after 30 days. The maximum of survival rate of earthworms was found in the mixture of cow dung, corn stalks and leaves with a ratio of 1:3:1(dry weight). The value was 87.5%.(3) Conducts the forced aeration composting and manually turned windrow of the mixture of cow dung, corn stalks and leaves with a ratio of 1:3:1 as pre-treatment. The C/N and content of organic matter all declined during composting. The total nitrogen increased slightly. The total phosphorus changed little. After inoculating with earthworms, The C/N and content of organic matter continued to decline. Total nitrogen, total phosphorus and available phosphorus were significantly increased. The total nitrogen increased to 1.30%(wt%) and 1.25%(wt%) from 1.09%(wt%), respectively. The total phosphorus increased to 0.612%(wt%) and 0.607%(wt%) from 0.490%(wt%) and 0.475%(wt%), respectively. The available phosphorus increased to 2.10 mg/kg and 1.95 mg/kg from 2.00 mg/kg and 1.44 mg/kg, respectively.(4) High emission concentration of CO2 was measured in the prior period of the forced aeration composting, and lower in the later period. Contrary to the forced aeration composting, high emission concentration of CO2 was measured in the later period of manually turned windrow, and lower in the prior period. After inoculating with earthworms, the emission concentration of CO2 was first decreased and then increased. It fell at lowest when finish.(5) Vermicomposting reduces emissions of CO2 as a result of the inoculation of earthworms. Turned windrow could be used as pre-treatment before vermicomposting. Keywords: rural waste; livestock manure; crop residues; vermicomposting;...