PARIO automatic instrument revolutionises soil particle size distribution analysis

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Labcell, the UK distributor for METER Group is introducing the METER PARIO soil particle size analyser, also known as the PARIO soil texture analyser. Unlike traditional techniques, the PARIO instrument is fully automatic, thereby eliminating the risk of human error and avoiding invasive actions that could disturb the suspended particles and introduce further errors. Once the soil sample has been prepared, the PARIO runs unattended, with results ready in around 6 to 8 hours.

The PARIO instrument calculates the particle size distribution using Stokes’ law for particles ranging in size from 1 µm to 63 µm with a resolution of 1 µm. Measurements are taken every 10 seconds, so the resulting particle size distribution (PSD) curve is both continuous and accurate. At each measurement point, a highly accurate pressure sensor reads the suspension pressure; temperature is read at the same time. With no need to insert a pipette or hydrometer at defined time periods, the sedimentation process is not disturbed. Furthermore, the instrument remains in situ throughout the analysis, so the measurement depth remains constant and another source of measurement error is avoided. The overall error rate using this Integral Suspension Pressure method (ISP) is just 3% and this is lower than any conventional soil particle size analysis method. An academic research paper concluded that the application of the ISP method to a real soil yielded results which were in excellent agreement with the results from the commonly used pipette method (‘The integral suspension pressure method (ISP) for precise particle-size analysis by gravitational sedimentation’ by Wolfgang Durner, Sascha C Iden and Georg von Unold, published in AGU Publications’ Water Resources Research on 6 January 2017).

Compared with alternative ways of analysing soil particle size distributions, the PARIO requires less time overall, so results are obtained more quickly. It also does not need a skilled laboratory technician, nor are measurements required to be made manually at potentially inconvenient times throughout a 24-hour period. Provided the sample is prepared correctly – and the procedure for this is the same as for the pipette method – the ISP method virtually eliminates the risk of human error. Measurements are made automatically and data is transferred to a computer via a USB port for logging and analysis.

The PARIO comes with user-friendly, comprehensive software for data inquiry, visualisation, evaluation and export. As the PARIO is part of METER’s LABROS system, it can be combined with the HYPROP, KSAT or WP4C to enable a soil’s physical and hydraulic properties to be characterised fully.

Labcell is the sole UK distributor for the METER range of instrumentation. Download detailed data sheets directly from Labcell’s website at or contact the company with specific enquiries or to request a demonstration by telephone on +44 (0)1420 568150 or email

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