Can be soil be hot by itself?

[SlowDemon]

I was transplanting my girls to bigger pot early this morning and the soil (small pot) felt sensibly warm. According to my (meat) thermometer, it was over 30°C (86°F), which is weird, because I have a computer monitoring & control system and temp never went over 23°C (in the closet) or over 18° (in the room) after switching on lights at 1:00 AM. I have several unrelated projects involving temp. control with Arduino and sensors (DS18B20, DHT11 and thermocouples), so I'm sure the readings are right +/- 2°C. In fact, my problem is that the closet is a little cold during the night (lights on). My closet have 345 W in 15 CFL, plus ventilation system.

So, what is happening? Do soil heat itself because of micro-organism? Is it dangerous for the roots?

Thanks

[StoneyTony]

Interesting. I'm wondering if the meat thermometer is not the right tool to measure that. If the plants look healthy I would say it's a bad reading and you shouldn't worry.

[Potted]

To answer your ? Yes soil can be hot ,very hot but u can't grow mj in it so what tony said is prob.right. Thier is a type of soil that is used by some here called smart soil it is put in the bottom of pots and is used in place of liquid fert.from what I have read it works well.my .02$ p.s. it's called kindsoil not smart soil sorry!

[PRIMO]

Spontaneous combustion can occur in moist compressed conditions when the bacteria does its fermentation thing. Think "pile of greasy rags started it" or a lone bale of hay in the middle of a field happily burning away. So if your soil was packed tightly and kinda moist--- not saying it would catch on fire, but yeah it can warm right up.