Estimating particle-size distribution from limited soil texture data

Particle-size distribution is a fundamental physical property of soils. Because particle-size data are frequently incomplete, it would be useful to have a method for inferring the complete particle-size distribution from limited data. We present a method for estimating the particle-size distribution from the clay (cl), silt (si), and fine plus very fine sand (fvfs) mass fractions (particle radii, r, between 25 and 125 mum). The method is easy to use, with the estimated distribution being given by a closed-form expression that is defined explicitly in terms of cl, si, and Ms. The accuracy of the method is evaluated using particle-size 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 mum less than or equal to r less than or equal to 1000 mum, and a maximum absolute deviation of 9%.