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Spectroscopy Laboratory

Soil and Crop Sensing Programme

The Soil and Crop Sensing Programme at Johnstown Castle has expertise and capabilities in Infra-red and X-ray fluorescence spectroscopy, in both benchtop and portable applications.  Optical sensing combined with Chemometrics/machine learning algorithms can be used to develop predictions for several parameters from a single spectrum.

Soil analysis:

  • total carbon
  • organic matter
  • nitrogen
  • aluminium
  • lime requirement
  • pH
  • cation exchange capacity
  • soil particle size (sand, clay and silt)
  • mechanistic properties such as phosphorus sorption and binding

Grass analysis spectroscopy offers rapid analysis of:

  • carbon
  • nitrogen
  • protein
  • dry matter.

Using molecular spectroscopy we can obtain high quality soil and crop information with improved precision to better understand the link between soil characteristics, crop productivity and nutrition.

Infra-red Spectroscopy

Our molecular spectroscopy laboratories at Teagasc Johnstown Castle are equipped with state-of-the-art benchtop and portable spectrometers in FTIR.  We use benchtop FTIR to generate large spectral libraries using the Bruker Invenio, launched in 2019 and procured by Teagasc in 2020. 

The Bruker Invenio at Teagasc laboratories is capable of scanning in the Near and Mid infra-red ranges and uses the mercury cadmium telluride (MCT) detector, which is the most advanced detector for commercial applications. This spectrometer is equipped with an extended range beamsplitter offering 10,000 to 6,00 wavenumbers for MIR and NIR spectral acquisition in one scan. For generating global spectral libraries our Bruker FTIR is coupled with a high throughput autosampler (Bruker HTS) with customised sample well plates for scanning up to 100 samples per run.  For soil analysis we measure in transmission and diffuse reflectance modes using ATR and DRIFT.


Handheld FTIR

For some soil parameters, the spectroscopy programme at Teagasc has progressed our predictions from benchtop to portable applications in FTIR. This lab area is equipped with the Agilent 4300 handheld FTIR spectrometer. This is a portable instrument weighing only ~2 kg, ideal for mobile non-destructive spectral acquisition in the field and non-laboratory environments. The instrument is able to collect MIR spectra in a few seconds, allowing for high spatial resolution spectral scanning.


X-Ray Fluorescence Spectroscopy

The XRF laboratory at Johnstown Castle uses benchtop and portable XRF to determine the total elemental composition of soil and plant samples. Unlike the traditional analytical methods, XRF does not require any acid digestion techniques before the sample analysis, allowing for faster run times for soil and crop analysis. Currently the XRF Laboratory is composed of two instruments, Rigaku NEX CG and TITAN S1 Bruker handheld XRF.

The Energy Dispersive XRF - Rigaku Nex Qc is a multi-element, multi-purpose analyser, ideal for measuring ultra-low and trace element concentrations into the percent levels. The spectrometer delivers rapid qualitative and quantitative determination of major and minor atomic elements in a wide variety of sample types with minimal sample preparation.

The TITAN S1 Bruker handheld XRF is a portable spectrometer able to analyse the elemental (Mg – U) from several samples, including soils, plants, oils, among others. The spectrometer was designed for field analysis, enabling perform analysis in a cheap, fast and accurate way, without a laboratory infrastructure.

Sample preparation for soils and crops in ED-XRF

SPECAC Manual Hydraulic Press - 25 Ton

Sample preparation in XRF analysis is a critical step in the quality of analytical results. The samples to be analysed using XRF spectrometers should present a flat analytical surface. Also, the sample must have a critical depth for penetration of all X-rays, be stable and homogenous. For this, pellet preparation is essential, especially when using benchtop spectrometers. In the Spectroscopy Laboratory, we use a Manual Hydraulic Press to prepare pellets.



Spectroscopy Publications

Our recent publications in molecular spectroscopy

K. Metzger, C. Zhang, K. Daly, From benchtop to handheld MIR for soil analysis: Predicting lime requirement and organic matter in agricultural soils, Biosyst. Eng. 204 (2021) 257–269. https://doi.org/10.1016/j.biosystemseng.2021.01.025.

K. Metzger, C. Zhang, M. Ward, K. Daly, Mid-infrared spectroscopy as an alternative to laboratory extraction for the determination of lime requirement in tillage soils, Geoderma. 364 (2020) 114171. https://doi.org/10.1016/j.geoderma.2020.114171.

K.S. Dunne, N.M. Holden, S.M. O’Rourke, A. Fenelon, K. Daly, Prediction of phosphorus sorption indices and isotherm parameters in agricultural soils using mid-infrared spectroscopy, Geoderma. 358 (2020) 113981. https://doi.org/10.1016/j.geoderma.2019.113981.

F.B. de Santana, A.M. de Souza, R.J. Poppi, Green methodology for soil organic matter analysis using a national near infrared spectral library in tandem with learning machine, Sci. Total Environ. 658 (2019) 895–900. https://doi.org/10.1016/j.scitotenv.2018.12.263.

F.B. de Santana, A.M. de Souza, R.J. Poppi, Visible and near infrared spectroscopy coupled to random forest to quantify some soil quality parameters, Spectrochim. Acta - Part A Mol. Biomol. Spectrosc. 191 (2018) 454–462. https://doi.org/10.1016/j.saa.2017.10.052.

F.B. de Santana, S.K. Otani, A.M. de Souza, R.J. Poppi, Comparison of PLS and SVM models for soil organic matter and particle size using vis-NIR spectral libraries, Geoderma Reg. 27 (2021) e00436. https://doi.org/10.1016/j.geodrs.2021.e00436.

Our Recent Publications in XRF spectroscopy

Croffie, MET., Williams, P.N., Fenton, O., Fenelon, A. and Daly, K. Rubidium measured by XRF as a predictor of particle size in limestone and siliceous parent materials.  J. Soils and Sediments

MET Croffie, PN Williams, O Fenton, A Fenelon, K Metzger, K Daly. 2020. Optimising Sample Preparation and Calibrations in EDXRF for Quantitative Soil Analysis Agronomy 10(9), 1309; https://doi.org/10.3390/agronomy10091309

McCarthy, William P; Daly, Karen; Fenelon, Anna; O'Connor, Christine; McCarthy, Noel A; Hogan, Sean A; Tobin, John T; O'Callaghan, Tom F. 2020. Energy‐dispersive X‐ray fluorescence spectrometry as a tool for the rapid determination of the five major minerals (Na, Mg, K, P and Ca) in skim milk powder. International Journal of Dairy Technology. 73. 2, 459-467.

Karen Daly, Owen Fenton, S.M. Ashekuzzaman, Anna Fenelon; 2019. Characterisation of dairy processing sludge using energy dispersive X-ray fluorescence spectroscopy. Process Safety and Environmental Protection. 127. 216-210

Karen Daly and Anna Fenelon. 2018. Application of Energy Dispersive X-ray Fluorescence (EDXRF) Spectroscopy for the Determination of Copper, Manganese, Zinc and Sulphur in Grass (Lolium perenne) in Grazed Agricultural Systems. Applied Spectroscopy. Doi: 10.1177/00037028.

Daly, K. and Fenelon, A.  2017. A rapid and multi-element method for the analysis of major nutrients in grass (lolium perennae) using energy dispersive X-Ray fluorescence spectroscopy. Irish Journal of Agriculture and Food Research.  1-11. DOI: 10.1515/ijafr-2017-0001