Soil analysis with NIR spectroscopy

Soil is a complex matrix made of organic and inorganic mineral matter, water, and air. There are many different factors that affect how soil behaves, one of which being the texture of soil which is dependent on the amount of sand, silt, and clay it contains.

Cation-exchange capacity (CEC) is a measure of the ability to hold positively charged ions, and it influences soil structure stability, nutrient availability, pH, and its reaction to fertilisers and other ameliorants. The main ions associated with CEC in soils are Ca2+, Mg2+, Na+, and K+. Soil pH directly influences the availability of nutrients to plants, microbial activity, and overall soil health, affecting plant growth, and crop yields.

This study describes how organic matter, pH value, silt, clay, sand, calcium and magnesium were measured in soil in seconds by using near-infrared spectroscopy (NIRS). This high-throughput method not only simplifies lab workflows, but also reduces costs and exposure to chemicals, whilst delivering reliable results for routine soil quality monitoring. By eliminating the need for solvents and extensive preparation, Metrohm’s NIRS solution can enhance both productivity and sustainability in soil testing.

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