Measuring sand content using sedimentation, spectroscopy, and laser diffraction

Summary

This laboratory study compared five soil particle size measurement methods using 121 Wisconsin sand plain samples, finding that whilst spectroscopic methods avoid assumptions inherent in sedimentation approaches, their accuracy depends critically on calibration data source. Mid-infrared spectroscopy provided the best predictions of total sand content (R² = 0.91–0.94) when calibrated with pipette method data, though sand fraction predictions remained moderately to poorly accurate (R² = 0.23–0.71 for MIR). The authors conclude that method selection and calibration protocol significantly affect results for soils with high sand content.

UK applicability

The findings are applicable to UK soil laboratories and research programmes that measure particle size distribution, particularly for sandy or coarse-textured soils. However, UK conditions and soil types may differ from Wisconsin's central sand plains, and validation with British soils would strengthen confidence in method recommendations for domestic practice.

Key measures

Sand content (2,000–50 µm) and five sand fractions (very coarse, coarse, medium, fine, very fine); coefficients of determination (R²) for method predictions; agreement between hydrometer, pipette, laser diffraction, vis-NIR and MIR spectroscopy

Outcomes reported

The study compared sedimentation (hydrometer and pipette), laser diffraction, and spectroscopic (vis-NIR and MIR) methods for measuring sand content and sand fractions across 121 soil samples from Wisconsin. It evaluated the accuracy, comparability and limitations of these methods in terms of total sand content and five sand particle size fractions.

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