Interpretation of Mid Infrared (MIR) Spectra of Soils - FULL

 Image illustrating a soil profile, FTIR spectrometer and FTIR spectrum of the top horizon of the soil in the MIR range

Image illustrating a soil profile, FTIR spectrometer and FTIR spectrum of the top horizon of the soil in the MIR range

he infrared region of the spectrum  is widely  used  for soil sensing and monitoring.  To date, the  near  infrared  (NIR)  region  has  been  far more  extensively  used  than  the  mid infrared  (MIR) region. However, MIR  spectra  can  provide  more information, particularly in  relation  to mineralogy,  than  NIR  spectra.    Hence MIR  spectra  give  more  complete chemical  profiles or “fingerprints” of soil  and,  in addition,  are more readily interpreted. An  MIR spectrum  is  generated  by plotting  absorption  against  frequency, which  to  the untrained  eye  can  appear meaningless.  Though much of the  information  concealed  in these  absorption  bands  can ultimately  be  extracted  via  chemometrics  and statistical modelling, the ability to  interpret the MIR spectra  is  fundamental  to obtain preliminary information that will help us understand the nature of the soil sample(s).  In  a  typical  MIR  spectrum,  different  absorption bands  are  observable  along  the frequency  range  (4000-400 cm-1) and  are  related  to  the  type  of  chemical  bonds  and functional groups present in the substrate. These bands occur at specific frequencies for particular  chemical  components,  thus  making  it possible  to  infer  the  organic  and inorganic  constituents  of  a  sample.  The  MIR spectra  can  therefore  be  invaluable  in providing a rapid insight into,  and a means of visualising,  the differences between soils. Although interpreting  MIR  spectra  of  soil  can  be  difficult  and complex,  with  some training  in  spectral  interpretation,  aspects  of  the  soil  such  as the  nature  and  relative proportions  of  organic  matter, minerals  and  clay  minerals  can  all  be  readily  assessed. Training  in  MIR  spectral interpretation  of  soil  is  not  readily  available,  and  so this workshop aims to try and address this by providing  the attendees with  an overview and basic  guidance  on  the  fundamental  steps  required for  an  accurate  diagnostic assessment of soil MIR spectra. 


  1. Introduction to MIR spectra of soil (presentation/lecture) – 30 min
  2. Spectral features of organic soils (presentation/lecture) - 30 min + practical exercise -15 min
  3. Spectral features of mineral soils - (presentation/lecture) - 30 min + practical exercise -15 min
  4. Practical exercise – interpretation of soil spectra – 1 hour
  5. Summary/ discussion – 30 min


Participants may either use their own laptops with software pre-installed or use one of the computers which will be made available. Spectral files and other materials will be made available during the workshop.


Jean Robertson
Jean has been head of the IR section at The James Hutton Institute for over 10 years, working with both Fourier Transform Infrared spectroscopy (FTIR) and Near Infrared (NIR) spectroscopy. She trained as a chemist, and her expertise in FTIR spectroscopy was first developed through her PhD, awarded in 1990, in which she studied structures of organometallic compounds. Through her work at the Institute she now applies this expertise in IR spectroscopy to a wide range of naturally occurring samples. She has developed the specialist knowledge necessary for interpreting the complex FTIR spectra of minerals, soils, sediments, fungal species and vegetation. In addition, from the samples generated for the National Soil Inventory of Scotland, she has been responsible for the creation of high quality FTIR and NIR national spectral datasets for Scotland. Much of her research relates to analysis of relationships between this spectral data and the other data held for the soils. She is also responsible for providing commercial FTIR analysis for a wide range of industrial clients.
The James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH, Scotland (UK)


Estefania Perez-Fernandez ep40279.JPG

Estefanía Pérez-Fernández
Estefanía is a biologist by training and gained her PhD with the University of Seville (Spain), in collaboration with The James Hutton Institute (Scotland), where she specialized in the use of near infrared spectroscopy for the study of animal ecology (herbivores). She has ample expertise in the application of chemometrics to develop predictive calibrations that allow estimation of a range of chemical properties of different types of natural samples, mainly soil, vegetation and animal faeces. Currently undertaking post doc research within the IR Section at The James Hutton Institute, Estefanía is in charge of developing new applications for crop, plant and soil research using both FTIR (Fourier Transform Infrared) spectroscopy and NIR (Near Infrared) spectroscopy analytical techniques. In addition to this, she also collaborates with the commercial analysis of samples from the oil, gas, engineering and food industries.
The James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH, Scotland (UK)