Importance

Soil colour can provide an indirect measure of other more useful properties of the soil that are not assessed so easily and accurately. A change in colour can give a general indication of a change in organic matter under a particular land use or management. Soil organic matter plays an important role in regulating most biological, chemical and physical processes in soil, which collectively determine soil health. It promotes infiltration and retention of water, helps to develop and stabilize soil structure, reduces the potential for wind and water erosion, and indicates whether the soil is functioning as a carbon “sink” or as a source of greenhouse gases.

Assessment

• Compare the colour of a handful of soil from the structure test with soil taken from the nearest uncultivated area.
• Using the three photographs, compare the relative change in soil colour that has occurred. As topsoil colour can vary markedly between soil types, the photographs illustrate the trend rather than the absolute colour of the soil.

Good
Moderate
Poor

Scoring

Good condition: Score 2

Dark coloured topsoil that is not too dissimilar to that from the uncultivated area.

Moderate condition: Score 1

The colour of the topsoil is somewhat paler than the uncultivated area, but not markedly so.

Poor condition: Score 0

Soil colour has become significantly paler compared with the uncultivated area.

References

http://adlib.everysite.co.uk/adlib/defra/content.aspx?id=000HK277ZX.0HDECKKQLJIF9JD