Clay, silt and sand (differnt sized particles of rock)
Humus, compost, peat moss, manure, etc.
Air and water
There is a well known saying that "a good gardener grows plants and a great gardener grows soil." Soil is the foundation of your garden, you take care of it and it will take care of your plants.
Source: Ideal soil mixture
The ideal soil is a mixture of 50% solids and 50% pore spaces. The pore spaces are filled evenly with water and air. The soilds are mostly minerals with some organic matter.
The final soil is a mixture of 25% water, 25% air, 45% minerals and 5% organic matter.
Source: Flooding
The most common soil mixture problems are:
The process of preparing soil for planting by mechanically stirring and overturning it (at the right time!).
The actions of a billion microorganisms that add organic matter, cycle nutrients, and create biodiversity, making the soil alive.
The evolution of soil characteristics, including the chemical and physical changes of soil, the development of soil profiles, and the accumulation of organic matter.
Soil provides plants with: