3 Soil spectroscopy tools and users

3.1 Soil Spectroscopy Instruments

Figure 1.3: Most frequently used MIR / VISNIR instruments based on Benedetti and van Egmond (2021).

3.1.1 Bruker Alpha 1_FT-MIR_Zn Se

• 🆔 Bruker_Alpha1_FT.MIR.Zn.Se
• 🏭 Producer: Bruker
  
• 🔗 Documentation: https://www.bruker.com/
  
• 📂 Model type: MIR (4000-400 cm^-1)
  
• 📅 Production year: 2012

3.1.2 Bruker Alpha 1_FT-MIR_KBr

• 🆔 Bruker_Alpha1_FT.MIR.KBr
• 🏭 Producer: Bruker
  
• 🔗 Documentation: https://www.bruker.com/
  
• 📂 Model type: MIR (4000-400 cm^-1)
  
• 📅 Production year: 2012

3.1.3 Bruker Vertex 70 with HTS-XT accessory

• 🆔 Bruker_Vertex_70.HTS.XT
  
• 🏭 Producer: Bruker
  
• 🔗 Documentation: https://www.bruker.com/en/products-and-solutions/infrared-and-raman/ft-ir-research-spectrometers/vertex-research-ft-ir-spectrometer.html
  
• 📂 Model type: MIR (4000-400 cm^-1)
  
• 📅 Production year: 2012

3.1.4 ASD Labspec 2500 with Muglight accessory

• 🆔 ASD_Labspec_2500_MA
  
• 🏭 Producer: Malvern Panalytical Ltd / Spectris
  
• 🔗 Documentation: https://www.malvernpanalytical.com/en/products/product-range/asd-range/labspec-range
  
• 📂 Model type: NIR (350nm - 2500nm)
  
• 📅 Production year: 2018

3.1.5 ASD FieldSpec FR

• 🆔 ASD_FieldSpec_FR
  
• 🏭 Producer: Analytical Spectral Devices, Inc.
  
• 🔗 Documentation: https://www.laboratorynetwork.com/doc/fieldspec-pro-fr-portable-spectroradiometer-0001
  
• 📂 Model type: NIR (350nm - 2500nm)
  
• 📅 Production year: 2016

3.1.6 XDS Rapid Content Analyzer

• 🆔 XDS_Rapid_Content_Analyzer
  
• 🏭 Producer: FOSS NIRSystems Inc.
  
• 🔗 Documentation: https://www.selectscience.net/products/xds-rapid-content-analyzer/?prodID=106696
  
• 📂 Model type: NIR (Si 400–1100 nm and PbS 1100–2500 nm detectors)
  
• 📅 Production year: 2008

3.2 Registered soil spectral libraries

3.2.1 KSSL.SSL

Description: MIR and NIR spectral library and associated soil characterization database, which now includes >50,000 MIR spectra collected on soils primarily from the United States. Freely available by request (see below).

• 📕 Seybold, C. A., Ferguson, R., Wysocki, D., Bailey, S., Anderson, J., Nester, B., … & Thomas, P. (2019). Application of Mid‐Infrared Spectroscopy in Soil Survey. Soil Science Society of America Journal, 83(6), 1746-1759. https://doi.org/10.2136/sssaj2019.06.0205 / Sanderman, J., Savage, K., & Dangal, S. R. (2020). Mid‐infrared spectroscopy for prediction of soil health indicators in the United States. Soil Science Society of America Journal, 84(1), 251-261. https://doi.org/10.1002/saj2.20009
  
• 🔗 Project website: https://www.nrcs.usda.gov/wps/portal/nrcs/main/soils/research/
  
• ©️ Data license: CC-BY
  
• 📍 Unique sites: 61,103
  
• 📋 Unique complete scans:
  
• 📝 Import steps: KSSL

Figure 3.1: KSSL VisNIR spectral signatures for different soil texture fractions.

3.2.2 ICRAF.ISRIC

Description: A Globally Distributed Soil Spectral Library Mid Infrared Diffuse Reflectance Spectra. MIR scans for some 785 profiles from the ISRIC World Soil Reference Collection. The samples are from 58 countries spanning Africa, Asia, Europe, North America, and South America. Data available under the CC-BY 4.0 license.

• 📕 World Agroforestry Centre, (2014). The ICRAF/ISRIC spectral library, Soil-Plant Spectral Diagnostics laboratory, United Nations Avenue, Nairobi, Kenya. https://doi.org/10.34725/DVN/MFHA9C
  
• 🔗 Project website: https://www.worldagroforestry.org/sd/landhealth/soil-plant-spectral-diagnostics-laboratory/soil-spectra-library
  
• ©️ Data license: CC-BY 4.0
  
• 📍 Unique locations: 785
  
• 📋 Unique complete scans: 4308
  
• 📝 Import steps: ICRAF_ISRIC

Figure 3.2: ICRAF-ISRIC VisNIR spectral signatures for different soil texture fractions.

3.2.3 LUCAS.SSL

Description: LUCAS 2009, 2015 top-soil data. VisNIR scans of some 19,860 in 2009 (2012) and 21,859 points in 2015. Data available publicly under condition that “Graphical representation of individual units on a map is permitted as far as the geographical location of the soil samples is not detectable”. Additional 600 samples have been scanned by Woodwell Climate Research using an MIR instrument.

• 📕 Jones, A, Fernandez-Ugalde, O., Scarpa, S., (2020). LUCAS 2015 Topsoil Survey. Presentation of dataset and results, EUR 30332 EN, Publications Office of the European Union: Luxembourg, ISBN 978-92-76-21080-1, doi:10.2760/616084, JRC121325.
  
• 🔗 Project website: https://esdac.jrc.ec.europa.eu/resource-type/soil-point-data
  
• ©️ Data license: JRC License Agreement
  
• 📍 Unique locations: 41,719
  
• 📋 Unique complete scans: 41,719
  
• 📝 Import steps: LUCAS

3.2.4 AFSIS1.SSL

Description: Africa Soil Information Service (AfSIS) Soil Chemistry Phase I. MIR and VisNIR scans of 1903 georeferenced soil samples collected from 19 countries in Sub-Saharan Africa including a suite of wet chemistry data. Data available publicly under Open Data Commons Open Database License (“ODbL”) version 1.0, with attribution to AfSIS. Data retrieved from: https://registry.opendata.aws/afsis/ and https://doi.org/10.34725/DVN/QXCWP1.

• 📕 Vågen, T.-G., Winowiecki, L.A., Desta, L., Tondoh, E.J., Weullow, E., Shepherd, K., Sila, A., (2020). Mid-Infrared Spectra (MIRS) from ICRAF Soil and Plant Spectroscopy Laboratory: Africa Soil Information Service (AfSIS) Phase I 2009-2013. https://doi.org/10.34725/DVN/QXCWP1, World Agroforestry - Research Data Repository, V1, UNF:6:bMN2MBGqFewDKHPgIeRjog== [fileUNF].
  
• 🔗 Project website: http://africasoils.net/services/data/soil-databases/
  
• ©️ Data license: Open Database License (“ODbL”)
  
• 📍 Unique locations: 1903
  
• 📋 Unique complete scans: 3806
  
• 📝 Import steps: AFSIS

3.2.5 AFSIS2.SSL

Description: Africa Soil Information Service (AfSIS) Soil Chemistry Phase II. The three datasets for Tanzania (https://doi.org/10.34725/DVN/XUDGJY), Ghana (https://doi.org/10.34725/DVN/SPRSFN) and Nigeria (https://doi.org/10.34725/DVN/WLAKR2). Documentation of the datasets is available in Hengl et al. (2021). Data has been analyzed at the ICRAF Soil-Plant Spectral Diagnostics Laboratory, Nairobi, and the Rothamsted Research. From the 31,269 soil scans, only 820 (2.6%) have reference data atteched to it.

• 📕 Hengl, T., Miller, M.A.E., Križan, J., Shepherd, K.D., Sila, A., Kilibarda, M., Antonijevi, O., Glušica, L., Dobermann, A., Haefele, S.M., McGrath, S.P., Acquah, G.E., Collinson, J., Parente, L., Sheykhmousa, M., Saito, K., Johnson, J-M., Chamberlin, J., Silatsa, F.B.T., Yemefack, M., Wendt, J., MacMillan, R.A., Wheeler I. and Crouch, J. (2021) African soil properties and nutrients mapped at 30 m spatial resolution using two-scale ensemble machine learning. Scientific Reports, 11, 6130. https://www.nature.com/articles/s41598-021-85639-y.
  
• 🔗 Project website: https://data.worldagroforestry.org/dataverse/icraf_soils
  
• ©️ Data license: Creative Commons — CC0 1.0 Universal
  
• 📍 Unique locations: 367
  
• 📋 Unique complete scans: 820
  
• 📝 Import steps: AFSIS2

3.2.6 CAF.SSL

Description: The Central African Soil Spectral Library. MIR scans of some collected based on 1800 samples in Central Africa.

• 📕 Summerauer, L., Baumann, P., Ramirez-Lopez, L., Barthel, M., Bauters, M., Bukombe, B., Reichenbach, M., Boeckx, P., Kearsley, E., Van Oost, K., Vanlauwe, B., Chiragaga, D., Heri-Kazi, A. B., Moonen, P., Sila, A., Shepherd, K., Bazirake Mujinya, B., Van Ranst, E., Baert, G., Doetterl, S., and Six, J. (2021). The central African soil spectral library: a new soil infrared repository and a geographical prediction analysis, SOIL, 7, 693–715, https://doi.org/10.5194/soil-7-693-2021
  
• 🔗 Project website: https://github.com/laura-summerauer/ssl-central-africa
  
• ©️ Data license: CC-BY?
  
• 📍 Unique locations:
  
• 📋 Unique complete scans: 1852
  
• 📝 Import steps: CASSL

3.2.7 NEON.SSL

Description: The National Ecological Observatory Network (NEON) Soil Spectral Library. Soil samples were sent to KSSL and scanned using standard procedures.

• 📕 National Ecological Observatory Network, (2021). Data Product DP1.00096.001, Soil physical and chemical properties, Megapit. Provisional data downloaded from https://data.neonscience.org. Battelle, Boulder, CO, USA NEON. / Dangal & Sanderman (2020). Is Standardization Necessary for Sharing of a Large Mid-Infrared Soil Spectral Library? Sensors 20, 6729. https://doi.org/10.3390/s20236729
  
• 🔗 Project website: https://www.neonscience.org/samples/soil-archive
  
• ©️ Data license: CC-BY
  
• 📍 Unique locations:
  
• 📋 Unique complete scans: 305
  
• 📝 Import steps: NEON

3.3 Soil spetroscopy organizations

National and regional soil spectral laboratories actively processing soil samples and providing soil spectroscopy services, and other organizations and companies producing or using soil spectroscopy data.

See also: The Global Soil Laboratory Network (GLOSOLAN)

3.3.1 KSSL

• 📛 Name: The Charles E. Kellogg Soil Survey Laboratory (KSSL)
  
• 📫 Address: USDA-NRCS-NSSC, Federal Building, Room 152, Mail Stop 41/51, 100 Centennial Mall North Lincoln, NE 68508-3866, USA
  
• 🔗 Organization website: https://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/?cid=nrcs142p2_053895#laboratory
  
• 🔬 Types of services: USDA soil laboratory, MIR, VisNIR,

3.4 Soil Spectroscopy software

Open source and commercial software used to process soil spectral scans. See also this detailed review of software used for soil spectroscopy. Even more in-depth review of R packages used for soil spectroscopy can be found in Wadoux et al. (2021).

3.4.1 asdreader

• 📛 Name: asdreader
  
• 💼 Specialty: Reading ASD Binary Files in R
  
• 💻 Programming language: R project
  
• 🔗 Homepage: https://github.com/pierreroudier/asdreader
  
• 📕 Roudier, P. (2020). asdreader: reading ASD binary files in R. R package version 0.1-3 CRAN.
  
• ©️ License: GPL
  
• 📧 Maintainer: Pierre Roudier

3.4.2 prospectr

• 📛 Name: prospectr
  
• 💼 Specialty: Signal processing, Resampling
  
• 💻 Programming language: R project
  
• 🔗 Homepage: https://github.com/l-ramirez-lopez/prospectr
  
• 📕 Stevens, A., & Ramirez-Lopez, L. (2014). An introduction to the prospectr package. R Package Vignette, Report No.: R Package Version 0.1, 3.
  
• ©️ License: MIT + file LICENSE
  
• 📧 Maintainer: Leornardo Ramirez-Lopez

3.4.3 simplerspec

• 📛 Name: simplerspec
  
• 💼 Specialty: Soil and plant spectroscopic model building and prediction
  
• 💻 Programming language: R project
  
• 🔗 Homepage: https://philipp-baumann.github.io/simplerspec
  
• 📕 Baumann, P. (2020). simplerspec: Soil and plant spectroscopic model building and prediction. Packages R CRAN.
  
• ©️ License: GNU General Public License v3.0
  
• 📧 Maintainer: Philipp Baumann

References

Benedetti, F., and F. van Egmond. 2021. Global Soil Spectroscopy Assessment. Spectral soil data — Needs and capacities. Rome, Italy: FAO. https://doi.org/10.4060/cb6265en.

Hengl, Tomislav, Matthew AE Miller, Josip Križan, Keith D Shepherd, Andrew Sila, Milan Kilibarda, Ognjen Antonijević, et al. 2021. “African Soil Properties and Nutrients Mapped at 30 m Spatial Resolution Using Two-Scale Ensemble Machine Learning.” Scientific Reports 11 (1): 1–18. https://doi.org/10.1038/s41598-021-85639-y.

Wadoux, A. M. J. C., B. Malone, A. B. McBratney, M. Fajardo, and B. Minasny. 2021. Soil Spectral Inference with R: Analysing Digital Soil Spectra Using the R Programming Environment. Progress in Soil Science. Springer International Publishing.