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Partial Soil Sterilization Using Dry Heat in an Enclosed Cylindrical Heating Chamber

 Ronel S. Pangan1


A soil sterilizing machine, composed of an enclosed cylindrical heating chamber was fabricated and evaluated. The machine has a load capacity of around 60 kg. The main component of the machine is a cylinder which also serves as the heating chamber. An ordinary oil drum was used but it was reinforced by a steel plate at the bottom, the part which is directly heated. Fuel such as wood, charcoal, coconut shell or corn cobs can be used for heating. The machine can be closed on all sides and is equipped with a chimney to maximize the heat transfer from the burning of fuel as well as to prevent smoke inhalation by the operator. The components of the fabricated sterilizing machine can be easily disassembled and assembled making the machine portable. A stirrer composed of round and flat bars as bolt-on pegs and paddles were installed inside the heating chamber for mixing the soil to attain uniform heating. For the easy turning of the stirrer, a simple power train system made up of chain and sprockets were utilized.

Using the machine resulted to a much faster sterilization time of 46 minutes as compared to the traditional method of using a cooking vat which took about 70 minutes. Fuel consumption was around 5.3 kilos as compared to 9.8 kilos when the cooking vat was used. Results from the soil microbial analysis showed that the developed machine is comparable to the usual method. The developed machine is very easy to use and can be fabricated using locally available materials.

Keywords: partial soil sterilization, soil heating chamber, soil sterilizing machine

1Engineer III, Agricultural Mechanization Development Program, Institute of Agricultural Engineering, College of Engineer­ing and Agro-Industrial Technology, University of the Philippines Los Baños, 4031 College, Laguna, Philippines.