Soil-plant spectral diagnostics

iSDA has considerable experience with use of sensors for rapid assessment of soil and plant health, as part of our wider work on diagnostics.

iSDA’s Chief Scientist, Keith Shepherd, pioneered the use of diffuse reflectance spectroscopy for soil and plant analysis in Africa from the early 2000’s and has developed several global soil spectral libraries (see references below). He has helped establish soil spectroscopy in over 20 African laboratories, as well as in India, UK and USA.He has led the development of the Global Soil Spectral Library and Estimation Service, which aims to provide a free resource for estimating soil properties from anywhere in the world.

In 2020, Keith won the Foodshot Global Groundbreaker Prize - Innovating Soil 3.0 to further the application of soil spectroscopy on farms for soil quality assessment and guiding soil nutrient application. He helped establish soil spectroscopy in the Global Soil Laboratory Network (GLOSOLAN) of the Global Soil Partnership, hosted by FAO and the Soil Spectroscopy for Global Good network (SS4GG). Keith also contributed to the design and prototype testing of the NeoSpectra-Scanner.

In 2020, iSDA conducted a successful pilot on commercial delivery of handheld soil scanners in Kenya on ????? smallholder coffee farms. Virtual Agronomist can now accept soil property estimates from handheld scanners.

Selected references

• Shepherd KD and Walsh MG. (2002) Development of reflectance spectral libraries for characterization of soil properties. Soil Science Society of America Journal 66:988-998. https://doi.org/10.2136/sssaj2002.9880.
• Shepherd KD, Palm CA, Gachengo CN and Vanlauwe B (2003) Rapid characterization of organic resource quality for soil and livestock management in tropical agroecosystems using near infrared spectroscopy. Agronomy Journal 95:1314-1322. doi:10.2134/agronj2003.1314
• Shepherd, KD, Vanlauwe B, Gachengo CN Palm CA (2005) Decomposition and mineralization of organic residues predicted using near infrared spectroscopy. Plant and Soil 277:315-333. https://doi.org/10.1007/s11104-005-7929-y.
• Brown D, Shepherd KD, Walsh MG (2006). Global soil characterization using a VNIR diffuse reflectance library and boosted regression trees. Geoderma 132:273–290. https://doi.org/10.1016/j.geoderma.2005.04.025.
• Shepherd KD and Walsh MG (2007) Infrared spectroscopy—enabling an evidence-based diagnostic surveillance approach to agricultural and environmental management in developing countries. Journal of Near Infrared Spectroscopy 15: 1-19. https://doi.org/10.1255/jnirs.716.
• Terhoeven-Urselmans T, Vagen T-G, Spaargaren O, Shepherd KD. (2010). Prediction of soil fertility properties from a globally distributed soil mid-infrared spectral library. Soil Science Society of America Journal. 74:1792–1799. https://doi.org/10.2136/sssaj2009.0218.
• Towett, E.K., Shepherd, K.D, Cadisch, G. (2013). Quantification of total element concentrations in soils using total X-ray fluorescence spectroscopy (TXRF). Science of the Total Environment 463–464: 374–388. https://doi.org/10.1016/j.scitotenv.2013.05.068.
• Towett, E.K., Shepherd, K.D., Sila, A., Aynekulu, E., Cadisch, G. (2015). Mid-infrared and total x-ray fluorescence spectroscopy complementarity for assessment of soil properties. Soil Science Society of America Journal 79: 1375-1385. https://doi.org/10.2136/sssaj2014.11.0458.
• Towett, E.K., Drake, L., Shepherd, K.D. (2015). Plant elemental composition and portable X-ray fluorescence (pXRF) spectroscopy: Quantification under different analytical parameters. X-Ray Spectrometry 45: 117–124. https://doi.org/10.1002/xrs.2678.
• Viscarra Rossel, … Shepherd, K.D., … (2016). A global spectral library to characterize the world’s soil. Earth-Science Reviews 155: 198-230. https://doi.org/10.1016/j.earscirev.2016.01.012.
• Sila A M, Pokhariyal G P, Shepherd K D. (2016). Evaluating the utility of mid-infrared spectral subspaces for predicting soil properties. Chemometrics and Intelligent Laboratory Systems 153: 92–105. https://doi.org/10.1016/j.chemolab.2016.02.013.
• Johnson, J.M., Vandamme, E., Senthilkumard, K., Sila, A., and Shepherd, K.D., Saito, K. (2019). Near-infrared, mid-infrared or combined diffuse reflectance spectroscopy for assessing soil fertility in rice fields in sub-Saharan Africa. Geoderma 354: 113840. https://doi.org/10.1016/j.geoderma.2019.06.043.
• Towett, E.K., Drake, L.B., Acquah, G.E., Haefele, S.M., McGrath, S.P., Shepherd, K.D. (2020). Comprehensive nutrient analysis in agricultural organic amendments through non-destructive assays using machine learning. PLoS ONE 15(12): e0242821. https://doi.org/10.1371/journal.pone.0242821.
• ICRAF Soil-Plant Spectral Diagnostic Laboratory (2020). https://worldagroforestry.org/sd/landhealth/soil-plant-spectral-diagnostics-laboratory
• Johnson, J-M, Sila, A., Senthilkumar, K., Shepherd, K.D., Saito, K. (2021). Application of infrared spectroscopy for estimation of concentrations of macro- and micronutrients in rice in sub-Saharan Africa. Field Crops Research 270 (2021) 108222. https://doi.org/10.1016/j.fcr.2021.108222.
• Summerauer, L., Baumann, P., Ramirez-Lopez, L., …, Shepherd, K., … 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.
• Shepherd, K.D., Ferguson, R., Hoover, D., van Egmond, F., Sanderman, J., & Ge, Y. (2022). A global soil spectral calibration library and estimation service. Soil Security 7: 100061. https://doi.org/10.1016/j.soisec.2022.100061.