We calculated CIELAB hue differences ([DELTA][H.sup.*.sub.ab]) between chips of adjacent charts with identical Munsell chroma and value notation, as well as CIELAB chroma differences ([DELTA][C.sup.*.sub.ab]), and lightness differences ([Delta][L.sup.*]) between neighbouring chips at constant Munsell value and hue, and constant Munsell chroma and hue, respectively.
Munsell chroma and hue are plotted as polar coordinates, and a higher Munsell value is indicated by the greater size of the triangles (JAPAN 1970 and JAPAN 1987) or diamonds (USA 1975a and USA1975b).
For the remaining soil samples the variation in Munsell notation as a result of using different soil-colour charts showed the following trends: (i) A reddening in hue using the Japanese charts; (ii) an increase in Munsell chroma and also a slight increase in Munsell value using JAPAN1970 charts; (iii) a better agreement between Munsell notations found with the 2 American charts than that found with the 2 Japanese charts.
4 also shows a greater loss of Munsell chroma in the used Japanese charts, although only the differences for chroma /6 and /8 proved statistically significant.
As can be seen, the distribution of colours is quite regular, the lines of constant Munsell hue and contours of constant Munsell chroma defining a regularly spaced spider web (Melville and Atkinson 1985).
5c, d) appear unaligned, and the dots of constant Munsell chroma have lost their circular regularity.