Soil character

The character and make-up of the soil play an important part in the behaviour of soils and what they are used for. Two of the most important properties of soils are their texture and structure.

Soil texture is an expression used to describe the physical components of the soil. Words such as clay, sand and loam have been used since ancient times to distinguish soils with different properties. Four standard words are now used in various combinations - sand, clay, loam and silt to describe the proportions of sand-, silt- and clay-sized particles in a sample. This must not be confused with soil structure which describes the way these individual particles are assembled and bound into groups (aggregates).

Soil texture can give a guide to:

• Soil water - its retention and release to plants;
• Soil structure - its development and stability;
• Nutrient retention and availability;
• Activity and retention of residual soil-acting herbicides;
• Erodibility by wind and water;
• Stickiness and ease of cultivation;
• Drainage characteristics and suitability for artificial drainage;
• Cropping suitability;
• Soil temperature changes.