The most common reason for people "cooking" soil is.
1. Trying to make do with an outdoor dirt mix (indoor growing).
2. Reusing indoor soil that is infested.
IMHO it is much easier and cheaper in the long run to buy clean bagged soil & mix according to Subcool's recipe.
If you are going to put it in your oven be advised it stinks to high heaven & has a very powerful "linger" factor.
GWN