Sterilizing regular potting soil

[Laserbeak]

I have this big strawberry planter that I had to remove from outside and took all the plants out of it. It then languished in a corner for a while and started growing mold, having flies reproduce in it, and other nasty stuff. The soil was brand new, so I didn't want to throw it away so I put it in a two gallon bucket and dropped into a pressure canner with about two gallons of water surrounding it to sterilize it. It is still coming up to pressure, I guess it takes a long time because of the amount of wet soil that's in it.

For those who know about pressure cookers and canners, how long do you think it needs to remain at high pressure to get rid of all these nasties?