Advances in near-infrared (NIR) spectroscopy to assess soil health

Abstract

Diffuse reflectance spectroscopy in the near-infrared (NIR: 350-2500 nm) region offers a relatively rapid, non-destructive, and high throughput alternative to wet chemistry measurements of soil health. Infrared absorbance frequencies of soil constituents such as organic matter and clay minerals form the basis for developing reliable calibrations for predicting soil health indicators (SHI). To demonstrate suggested practices, and potential challenges to the use of NIR for soil health measurements, the chapter describes use of a NIR spectral dataset of diverse United States soils (n=709) from the USDA NRCS National Soil Survey Center to develop chemometric prediction models of representative SHI: total organic C (TOC), aggregate stability, clay content, and β-glucosidase activity. Future directions for NIR prediction of SHI and thus infrared spectroscopy-based soil health assessment and monitoring are also discussed.