What is soil?
Soil is the loose surface material that covers most land. It consists of inorganic particles and
organic matter. Soil provides the structural support to plants used in agriculture and is also
their source of water and nutrients.
Soils vary greatly in their chemical and physical properties. Processes such as leaching,
weathering and microbial activity combine to make a whole range of different soil types. Each
type has particular strengths and weaknesses for agricultural production.
The basic components of soil are minerals, organic matter, water and air. The typical soil consists of approximately 45%
mineral, 5% organic matter, 20-30% water, and 20-30% air. These percentages are only generalizations at best. In reality, the
soil is very complex and dynamic.
Physical characteristics of soil
The physical characteristics of soils include all the aspects that you can see and touch such as:
texture
colour
depth
structure
porosity (the space between the particles)
stone content.
Good soil structure contributes to soil and plant health allowing water and air movement into
and through the soil profile. Soil stores water for plant growth.
Soil texture, structure, drainage characteristics
Figure 1. Soil aggregate
