Estimating particle-size distribution from limited soil texture data

Particlesize distribution is a fundamental physical property of soils. Because particlesize data are frequently incomplete, it would be useful to have a method for inferring the complete particlesize distribution from limited data. We present a method for estimating the particlesize distribution from the clay (cl), silt (si), and fine plus very fine sand (fvfs) mass fractions (particle radii, r, between 25 and 125 m). The method is easy to use, with the estimated distribution being given by a closedform expression that is defined explicitly in terms of cl, si, and fvfs. The accuracy of the method is evaluated using particlesize data from 125 soils. The results show that the method should not be used when the silt fraction is greater than about 70%. For other soils, the estimated distribution agrees reasonably well with the true distribution, with the median level of accuracy being characterized by an average absolute deviation of 2% over 1 m r 1000 m, and a maximum absolute deviation of 9%.

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