Problem encountered when sterilizing soli.

[cactiask]

So last time I wanted to sterilize ordinary potting soil for planting seeds in an air tight container, the soil became strange.
I put the soil in the oven and sterilized it at the advised temperature or even below. Maybe I heated the soil for too long or something,
but afterwards, when I poured water on the soil in order to make it moist the soil would not get wet. Strangely enough, it was like pouring water on a duck's back, the soil would not soak up the water. And also, the soil felt light and lifeless.

I want to use ordinary potting soil (together with sand) instead of some other dedicated cacti mixture because my previous cacti are growing faster in the potting soil.

Any advice?

[Aiko]

The soil should be moist WHEN you cook / bake it.
I think you might have baked a brick.

[cactiask]

The water evaporates (boils) at high temperatures, so it is very conflicting to me to bake soil and still have it moist.

[greenknight]

Sounds like peat-based soil - dried peat resists water. Use very hot water to moisten dry peat, it will absorb.

"Sterilizing soil" is a misnomer More accurately, it's "pasteurized" to kill weed seeds, soil-borne insects, and pathogens, but not heated enough to totally sterilize it. Getting the soil too hot can create compounds that are bad for plants. It doesn't need to get boiling hot, for baking soil you want it to reach 180f (82c) for 30 minutes - only 140f is needed to kill insects and diseases, the higher temperature is needed to kill weed seeds. Start out with wet soil and cover it with aluminum foil to hold in the moisture. Use an oven thermometer inserted into the center of the soil (not touching the pan) to insure reaching the right temperature.

[Aiko]

The water evaporates (boils) at high temperatures, so it is very conflicting to me to bake soil and still have it moist.

Cook it in a pan, close the lid. I just use the stove and an old pan for this. If the soil dries out (maybe because you allow it to boil too long for what is needed), just add some water and keep cooking the soil until also that water is of boiling temperature. Ten minutes is enough for the soil to boil.

I always end up with a nice quite moist baking soil to use as sowing material. I just scoop it in a pot, allow the pots to cool down just a bit, then add the seeds and put the pots in a air tight container while still warm. They will stay locked up for a few weeks / months, depending.

[cactiask]

The water evaporates (boils) at high temperatures, so it is very conflicting to me to bake soil and still have it moist.

Cook it in a pan, close the lid. I just use the stove and an old pan for this. If the soil dries out (maybe because you allow it to boil too long for what is needed), just add some water and keep cooking the soil until also that water is of boiling temperature. Ten minutes is enough for the soil to boil.

I always end up with a nice quite moist baking soil to use as sowing material. I just scoop it in a pot, allow the pots to cool down just a bit, then add the seeds and put the pots in a air tight container while still warm. They will stay locked up for a few weeks / months, depending.

Thanks, I will try that!

[DaveW]

If you microwave soil remember in order to sterilise it it must be damp since microwaves will not heat dry substances. They work by vibrating water molecules which produces heat and as soon as there is no more water in the substance they stop heating.

See:-

https://www.bing.com/videos/search?q=ho ... &FORM=VIRE