Precipitation effect on colour characteristics of argillic horizons in well-drained soils developed under Mediterranean climate

This paper is a study of the effect of the climate, and above all of the precipitations, on the formation of the colour characteristics of value and chroma in the argillic horizons of soils that have developed in two regions of Greece with 500 mm difference between them in precipitation levels. Calculation of colour was effected through obtaining reflectance spectra in the range of the visible region in a fraction of smoothed soil less than 250 mm in diameter. From analysis of the reflectance spectra, the colour characteristics (hue-value-chroma) of the CIE system were calculated and subsequently converted into Munsell colour system readings. To ascertain the differences between the colour characteristics of the two regions, two linear statistical models were used in combination: the piecewise linear regression model and the nested linear model. Implementation of the piecewise linear regression model indicated that this model possesses a significant capability for predicting the value and chroma of argillic horizons. Implementation of the nested linear model on the predicted quantities emerging from the piecewise linear model revealed that different levels of precipitation do not lead to differentiation in the value and chroma in the argillic horizons of soils developed under Mediterranean climatic conditions.