Here is one of my bonsai trees.
There is something strange in the soil but I don't know what is that...
1. There are some white things in the soil
2. The soil looks quite black, not brown.
3. There is some kind of sand on the tree trunk, you will see in the pictures.
Hopefully you can give me some tips I am a beginner with bonsai trees. The first that I had was 7 months ago...