Material composition of soil

Soil consists of minerals (inorganic substances), air, water and organic matter, in which minerals are the main part and can be subdivided into sand (sand, silt) and clay according to particle size. The distribution of soil particles, that is, the composition of particles with different sizes, is called soil texture, and soil texture depends on its mineral composition.

Soil texture has a great relationship with soil physical properties, such as the difficulty of soil cultivation, nutrients and water storage capacity, aeration, water leakage rate and so on.

Sand grains in soil grains are mainly composed of primary minerals in soil-forming parent rocks (rocks), and clay grains are generated by primary minerals in soil-forming parent rocks (rocks) (see figure 1-4).