Water Management in Horticultural Crops (1+1)

Soil Profile

• If a pit is dug in the soil, at least 1 m deep, various layers, different in colour and composition can be seen. These layers are called horizons. This succession of horizons is called the profile of the soil.
• A very general and simplified soil profile can be described as follows:
1. The plough layer ( 20 to 30 cm thick): Rich in organic matter and contains many live roots. This layer is subject to land preparation and often has a dark colour of brown to black.
2. The deep plough layer: Contains much less organic matter and live roots. This layer is hardly affected by normal land preparation activities. The colour is lighter, often grey, and sometimes mottled with yellowish or reddish spots.
3. The subsoil layer: Hardly any organic matter or live roots are found. This layer is not very important for plant growth as only a few roots will reach it.
4. The parent rock layer: Consists of rock, from the degradation of which the soil was formed. This rock is sometimes called parent material.
• The depth of the different layers varies widely: some layers may be missing altogether.