I mean can use it for soil?

Yes. Just put some soil in a lidded jar, add water to make a slurry, screw the lid real tight and shake the dickens out of it, let it sit for 10 minutes, strain it through a cloth and use that water to test. It's not as much work as it sounds, and very useful.

Good luck.

Korina

Ou thanks
And can I use aquarium PH adhuster?