Rapid PXRF soil organic carbon and organic matter assessment using novel modular radiation detector assembly

Soil organic matter and organic carbon are variables of critical environmental importance in terms of soil productivity and function, global food security, and climate change mitigation. Rapid and accurate assessment of these variables is central to national programs and international agreements. Portable X-ray fluorescence instruments are widely used to rapidly quantify and map soil elements, however quantification of light elements that constitute the majority of organic materials is not yet possible with this technique (e.g. carbon). We developed a novel attachment for portable X-ray fluorescence instrumentation enabling concurrent volumetric soil organic matter and organic carbon quantification during PXRF analyses. This primary prototype outperformed more expensive visible-near infrared instrumentation using parsimonious soil specific simple linear regression (R² ranged 0.85–0.97) enabling rapid, parallel, nondestructive, cost-effective acquisition of soil elemental concentrations together with soil organic carbon and soil organic matter data.