If you don't buy it, you will find a lot of dirt. In fact, plants grow in the soil in the natural environment, so it is fun to find the soil by yourself.
Humus soil: under the arbor forest, the leaves without rotten epidermis are removed, and humus soil is below.
Clay: fine grain, paddy field.
Loam: average particle, vegetable garden.
Sandy loam: fine particles, loam mixed with sand.
Sandy soil: coarse particles, sand mixed with loam.
I suggest you forget the cinder. That guy doesn't gain weight, he has a lot of screening and a lot of work.
If you have a fermentor, you can also find some of these oils. It's very cheap to buy this in a vegetable oil factory.
In fact, humus+loam+sand can form a good soil for plant growth, and Bilie is mixed according to the characteristics of flowers.