Soils and the soils of Central Asia

Soil is the loose surface layer of land that has the property of fertility. Soil formation begins with weathering of rocks, but the rock broken into small pieces is not yet soil; it is called the parent rock. When plant and animal remains fall onto it and rot under bacteria and fungi, forming humus, and heat, moisture and air act on it, the rock gradually turns into soil. Soil has three parts: the parent rock, organic matter (including humus) and the soil solution, water with substances dissolved that plants need. Fertility is the soil’s ability to supply plants with water and nutrients, and it also depends on the amount of humus. By mechanical composition soil is clayey, loamy, sandy or gravelly; by adding fertiliser, irrigating, tilling and washing out salts it can be turned into fertile, cultivated soil. Erosion by water and wind, salinisation and pollution damage soil.