Soil Sampling

The term 'horizon' describes each of the distinctive layers that occur in a soil. Each soil type has at least one, usually three or four different horizons and these are described by soil scientists when seeking to classify soils. Horizons are defined in most cases by obvious physical features, colour and texture being chief among them. These may be described both in absolute terms (particle size distribution for texture, for instance) and in terms relative to the surrounding material, ie, ‘coarser’ or ‘sandier’ than the horizons above and below.