#soiltexture

Where the viscosity of fluids is naturally high flow is normally laminar. The Reynolds number is very small and, the expression derived George Gabriel Stokes in 1851 can be used to measure the viscosity of the fluid or the terminal velocity of spherical particles falling through the fluid. In the case of soils, Stokes' Law is used to predict the settling times for various sized particles, expressed as the percent of particles in the sand, silt, and clay size separates after organic matter, carbonates, and iron and manganese oxides and other cementing or binding agents are removed. This technique is in use in many labs worldwide unless soil sample must be dispersed in a liquid medium (ie altering the size distribution), being highly dependent upon fluid temperature, and quite abundant bulk samples were required. Many standards for soil measurements, observations, data collection and data management exist and the Global Soil Partnership will act to federate and facilitate a partnership among various actors to develop synergies and cost savings for all partners. A promising kickoff could be saving almost 150 USD when a lab decide to conform to ISO methods (ISO 11277:2009(en) — Determination of particle size distribution in mineral soil material).

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