Dig This – Particle Size Analysis of Soil

The particle size analysis of soil and ocean sediments helps to characterize a geological area according to texture properties. Soil texture properties determine the drainage ability of water and nutrients, as well as susceptibility to erosion. With the laser diffraction technique, the PSA allows performing fast and repeatable measurements over a wide size range from submicron clay to millimeter-sized sand.


The mineral fraction of soil is composed of sand, silt and clay, and the ratio of these components defines the soil texture. Plant or animal matter in various stages of decomposition forms the organic fraction of soil, which binds the mineral soil particles into aggregates. The particle size distribution is one of the most essential properties of soil and sediment. It determines characteristics such as bulk density, porosity, water retention, nutrient content and permeability among many others. The soil texture triangle depicted in Figure 1 shows the dependence on the component proportions[1]. It divides regions with different percentages of the three fractions into texture classes. However, different countries or regions divide up the texture triangle differently depending on the prevalence of their local soil types.


1. Micron Scientific Laboratory Instrumentation. Why are my laser diffraction results not repeatable or reproducible? micron scientific. [Online] www.micronscientific.co.za/contact-us/faq/whyare-my-laser-diffraction-results-not-repeatable-orreproducible.

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