The Ways to Do a Texture Classification for Laser Diffraction Method
The existing soil texture classifications were based on the data sedimentation. The aim of this article is to consider ways to solve the problem of using data from the laser diffraction method to classify soils according to particle size distribution. The article provides a detailed comparison of the data of particle size analysis of soils obtained by two methods – using laser diffractometry and the classical pipette method. We have showed the reproducibility of the laser diffraction method and the effect of oxidation stage on the soil texture class. This study is based on 8 types of soils (total 32 full sections) which form a zonal series, from podzols (Subpolar Urals) to ferrallite soil (Southwestern Oceania) differing in mineralogical composition, texture and in elementary soil processes. The direct use of the Kachynskiy and USDA classifications with the data of the laser diffraction method leads to mistakes in determining the texture class in 43 and 65% of cases. Increasing complexity of models’ conversion, introduction of new variables, and accounting for the influence of inter-laboratory mistake allow to determine correctly the texture class according to the Kachynskiy and USDA classifications in no more than 70 and 72% of soil samples. The most simple and effective approach to solve the classification problem for the laser diffraction method is to calibrate existing classifications directly on the basis of measuring by laser diffraction soil samples which texture class is determined by the field method.