The Granulometric Composition of Soils: History, Development of Methods, Current State, and Prospects

The problems of determination and classification of soils by granulometric composition from the point of view of domestic and international soil science are considered. The development of methods and devices for granulometric analysis of soils was largely promoted by the works of the Department of Soil Physics and Reclamation, on the basis of which the necessity of two stages of granulometric analysis was shown and the all-Russian method of sedimentation analysis of particles by the pipette method was created, with the development of the classification of N.A. Kachinsky and names of soils by granulometry, which are fundamentally different from those generally accepted in world practice. At present, at the first stage, the method of pretreatment with 4% sodium pyrophosphate is widespread, and at the second stage, measurement of granulometric composition, two approaches are used: the sedimentation method and laser diffractometry, which have different physical bases. The difference in the final results on granulometric composition of soils is usually associated with different shape and density of solid phase of organic and mineral particles. This paper presents the studies of granulometric composition of agrodernovo-podzolic sandy loam soil (Tver oblast, VNIIMZ experimental site) with a low content of organic matter in a comparison of three methods of granulometric composition determination: laser diffractometer, sedimentometric methods of suspension pressure estimation on a Pario ISP+ (integral suspension pressure) device, and the classical pipette method. The laser diffractometer for fine fractions showed systematically underestimated data with the same pretreatment procedure compared to the ISP and pipette method. The ISP+ method compared to the classical pipette method gives similar results.