Soil colour designation using Adobe Photoshop™ in estimating soil fertility restoration by Acacia auriculiformis plantation on degraded land

Using Adobe Photoshop™, we applied soil colour designation with the RGB (red, green, blue) and the CMYK (cyan, magenta, yellow, black) schemes in monitoring rehabilitative effects by Acacia auriculiformis on a degraded land. Soils were sampled from dry evergreen forest (the original vegetation), bare ground (the most severely degraded) and A. auriculiformis plantation plot for the rehabilitative experiment. Single soil physicochemical and colour variables showed few significant differences between the soils of the evergreen forest and the Acacia plantation, while multivariate profiles of these soils were discriminated by discriminant analysis using the physico-chemical or the colour dataset. These results indicate: (i) linkages between degradation–rehabilitation gradient and changes in soil colour; (ii) that the Acacia plantation soil was still in rehabilitation, though it largely restored the original soil conditions. Applicability of soil colour designation in monitoring rehabilitative effects on degraded lands was suggested.