heres what i found real quick
You can choose from four methods to sanitize soil at home.
Oven Method- Spread soil not more than four inches deep in non-plastic containers, such as seed flats, clay pots and glass or metal baking pans. Cover each container tightly with aluminum foil. Insert a meat or candy thermometer through the foil into the center of the soil. Set the oven between 180° and 200° F. Heat the soil to at least 180° F; keep at this temperature for 30 minutes. Do not allow the temperature to go above 200° F. High temperatures may produce plant toxins. After heating, cool, remove containers from the oven and leave aluminum foil in place until ready to use. The heated soil will give off an odor.
Microwave Oven Method-You also can sterilize soil in a microwave. Microwave soil for 90 seconds per kilogram (2.2 pounds) on full power. Don't use metal containers and aluminum foil when using a microwave. Two methods suggested by others are:
1. Fill clean, quart-size plastic containers with very moist soil, perlite or cutting medium. Check the rims of the containers to make sure there is no aluminum of any kind because some yogurt containers come with a foil seal. Use clean plastic yogurt containers with lids on for sterilizing soil. This is done using a temperature probe inside a carousel-type microwave oven, heating to 200F and holding that temperature with the digital oven program for 20 minutes. Poke a hole through the plastic lids with a nail for steam ventilation. The temperature probe goes half way down into the soil through this hole in one of the containers. In a large microwave, up to 7 quart containers can be sterilized at a time, making this a very efficient way to heat sterilize soil. Allow to cool and tape over the hole in the lid to keep sterile until ready to use.
2. Place approximately 2 pounds of moist soil in a polypropylene bag. Leave the top open and place in the center of a microwave oven. Treat for 2½ minutes on full power of about 650 watts. After treatment close the top of the bag and allow the soil to cool before removing