boiling the soil would not do the same thing. Water at sea level will not go to temperatures above 100 Celsius unless it is put under pressure. So 100 degrees will not kill the bacteria and really wont do anything. You use a pressure cooker which allows the pressure to get really high, which in turn keeps the water in liquid form at very high temperatures. This will kill the bacteria it is acutely the same principal behind autoclaves which are what sterilizes surgical equipment. This would also kill all beneficial bacteria and I don’t know if it is a good idea. What I did was buy some really good soil with lots of micro organisms and mixed it with other soils. My theory is that they will just multiply and spread through the soil.