Soil textural parameters are known to be correlated with colour (e.g. Konen et al., 2003). One of the most important factors relating textural class to soil colour is thought to be the level of aggregation, which is influenced not only by the organic matter content but also by the relative proportions of sand, silt and clay fractions (i.e. the texture) for the soil in question. Aggregated soils will have different hydraulic properties to non-aggregated, which will impact on the cation exchange, redox potential and coatings of soil particles. Each of these factors will have an impact on soil colour.