Composting of Separated Soil from Root Vegetables and Other Agricultural Residues and its Sterilizing Effect

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Separated soil from root vegetables (Sugar beets) contains not only organic matter and nutrition for plants but also a lot of pathogenic bacterias. Because of this reason it can not be returned to farm lands without sterilizing treatment in order to prevent diffusion of bacterias. A sterilizing method using microorganisms is expected to be a low cost and mass treatment.This project is carried out to find out a practical sterilizing method of the separated soil using heat generated from composting.The conclusions are as follows;1. When sugar beet manufactoring wastes which include separated soil are available for composting, optimum operating conditions are as follows; Mixing ratio(weight); Separated soil: Surplus sewage sludge: CSF(Concentrated Steffen Filtrate): Wheat straw = 81:13:2:4, Moisture content; 45% wd., Aeration rate; 0.5 1/min.kg DM, Aeration time; Blower on 6 min., Blower off 14 min., 20 min. cycle.2. To begin to raise temperature of compost rapidly, material temperature should be maintained above at least 5゜C, if possible above 10゜C.3. Killing of pathogens results from a combination of time and temperature. Pathogens are killed completely if the temperature of compost is kept above 55゜C for 3 weeks.4. Temperature of the compost rises rapidly during even the coldest winter, if the above operating parameters are within optimum ranges. But temperature difference between surface or bottom part and central part may often arise without sufficient insulators.5. The separated soil after composting (Produced compost) has a high pH value and inhibits germination of plants, but after curing it has very good effect on plant growth and disease inhibition.6. This forced aeration pile method can be applied to the composting of every agricultural residue as long as a bulking agent like wheat straw or wood chips is available.