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R.A. Viscarra Rossel and B. Stenberg, J. Near Infrared Spectrosc. 24, v–vi (2016)
JOURNAL OF NEAR INFRARED SPECTROSCOPY Special Issue: Near Infrared Spectroscopy of Soil
Guest Editorial: Near infrared spectroscopy for a better understanding of soil Raphael A. Viscarra Rossela and Bo Stenbergb a
CSIRO Land & Water, PO Box 1700, Canberra ACT, Australia. E-mail:
[email protected] Swedish University of Agricultural Sciences, Department of Soil and Environment, Skara, Sweden. E-mail:
[email protected]
b
The 68th United Nations General Assembly declared 2015 as the International Year of the Soil (IYS 2015) because soil is profoundly important for life. The Food and Agriculture Organisation (FAO) was nominated to implement the IYS 2015 to increase awareness and understanding of the importance of soil for food security, climate mitigation and essential ecosystem functions. Other specific objectives of the IYS 2015 were to educate the public about the importance of soil, support policies for the protection of the soil resource, promote investment to maintain healthy soil, strengthen sustainable soil management initiatives and advocate for a rapid enhancement of capacity to collect soil information for monitoring at all scales from the regional to national and global. Thus we thought it fitting to support the IYS 2015 activities and develop a special issue in JNIRS—Journal of Near Infrared Spectroscopy dedicated to the application of near infrared (NIR) spectroscopy in soil science. NIR spectroscopy has a clear role to play in the provision of good quality soil information at different scales, as it can be used to rapidly and precisely characterise the chemical, physical and mineralogical composition of the soil at a small cost. This volume contains ten original contributions from around the world. It is evident in most of these papers that the mentioned advantages of NIR spectroscopy, as well as the little sample preparation needed and the simultaneous determination of many soil attributes, are the reasons for using NIR spectroscopy when seeking quantitative data on soil. NIR is particularly attractive for soil analyses because many measurements are needed to characterise the diverse composition and functions of soil, which can vary greatly over different scales. It is also evident that soil organic matter and especially its carbon and nitrogen contents are of primary interest to analysts seeking to use NIR spectroscopy. While applications of NIR spectroscopy for assessments of soil organic matter ISSN: 0967-0335 doi: 10.1255/jnirs.1234
date back to earlier work in the 1980s1 the papers in this issue bring new insights to its potential benefits. For example, Barthès et al.2 report a detailed comparison of the benefits of NIR and mid-infrared spectra to analyse soil organic and inorganic carbon and suggest how temperature and sample preparation influence the protected carbon in a soil sample. Water repellency can affect plant growth in many regions of the world. Knadel et al.3 report that there is good potential for NIR spectroscopy to estimate water repellency and that the relationships are not simply due to indirect calibrations with total organic matter or other soil properties but rather with the quality of the organic fraction. Working with loess soils and photoacoustic spectroscopy (PAS) Changwen et al.4 have demonstrated the potential of PAS for the rapid determination of organic matter and clay in soil. Soil water content affects NIR spectra and may hide useful information that is evident in a dry sample. Wang and Pan5 report that the external para meter orthogonalisation algorithm can successfully remove some of the water effect and improve the prediction of soil organic matter in soil samples that are wet. The reflectance of NIR wavelengths from soils is inversely related to the size of the natural aggregates formed in soil and influence the accuracy of NIR-based determinations. de Oliveira et al.6 report on the interaction between microaggregate size and the reflectance of NIR wavelengths. Chemometrics has long been a powerful ally to NIR spectroscopists. By applying the continuous wavelet transformation to spectra of soils in combination with competitive adaptive reweighted sampling and partial least squares, Vohland et al.7 report improvements in the predictions of soil organic carbon. For discrimination of soil types Todorova and Atanassova8 report an application of soft independent modelling of class analogy. In agriculture, the use of chemicals is widespread and can lead to environmental pollution. Paradelo et al.9 report on the © IM Publications LLP 2016 All rights reserved
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Guest Editorial: Near Infrared Spectroscopy for a Better Understanding of Soil
use of NIR spectroscopy to assess the potential ability of a soil to sorb such pollutants. They explain that the ability to predict sorption capacity is correlated with soil organic matter, aluminium oxides and cation exchange for some chemicals and with clay minerals and iron oxides for other chemicals; and soil pH can aid the accuracy of the analysis. The reputation of a soil analytical laboratory is paramount and it must stand up to national or international scrutiny. de Souzaa et al.10 report an inter-laboratory study which demonstrated the robustness of NIR spectroscopy for soil organic matter determinations that is employed by over a hundred soil laboratories in Brazil. Also at a national scale, Fernández and Robertson11 report on the application of NIR spectroscopy and LOCAL calibrations to assess and monitor the chemical and physical properties of the soil of Scotland. The papers in this issue demonstrate some of the recent applications of NIR spectroscopy for the study of soil. We hope that you enjoy reading these papers and that you will find them useful. We thank JNIRS and its Editor-in-Chief, Graeme Batten, for supporting the idea and providing the authors with many editorial suggestions to improve their scripts. We thank the anonymous reviewers of the manuscripts and, of course, we thank all the authors without whom this special issue would not have been possible. We hope that this special issue will enhance the discussion on soil in our communities and prompt new ideas and collaborations. The future of soil spectroscopy is in the development of larger, more coordinated collaborations. The global soil spectral library (Viscarra Rossel et al.)12 should provide a good platform for this.
References 1. R.C. Dalal and R.J. Henry, “Simultaneous determina-
tion of moisture, organic carbon, and total nitrogen by near infrared reflectance spectroscopy”, Soil Sci. Soc. Am. J. 50, 120–123 (1986). doi: http://dx.doi.org/10.2136/ sssaj1986.03615995005000010023x 2. B.G. Barthès, E. Kouakoua, P. Moulin, K. Hmaidi, T. Gallali, M. Clairotte, M. Bernoux, E. Bourdon, J. Toucet and T. Chevallier, “Studying the physical protection of soil carbon with quantitative infrared spectroscopy”, J. Near Infrared Spectrosc. 24, 199 (2016). doi: http://dx.doi. org/10.1255/jnirs.1232 3. M. Knadel, F. Masís-Meléndez, L.W. de Jonge, P. Moldrup, E. Arthur and M.H. Greve, “Assessing soil water repellency of a sandy field with visible near infrared spectroscopy”, J. Near Infrared Spectrosc. 24, 215 (2016). doi: http://dx.doi.org/10.1255/jnirs.1188 4. D. Changwen, M. Fei, S. Yazhen and Z. Jianmin, “Characterisation of loess soils using near infrared pho-
toacoustic spectroscopy”, J. Near Infrared Spectrosc. 24, 225 (2016). doi: http://dx.doi.org/10.1255/jnirs.1176 5. C. Wang and X. Pan, “Improving the prediction of soil organic matter using visible and near infrared spectroscopy of moist samples”, J. Near Infrared Spectrosc. 24, 231 (2016). doi: http://dx.doi.org/10.1255/jnirs.1184 6. J.F. de Oliveira, M. Brossard, E.J. Corazza, R.L. Marchão and M. de Fátima Guimarães, “Visible and near infrared spectra of Ferralsols according to their structural features”, J. Near Infrared Spectrosc. 24, 243 (2016). doi: http://dx.doi.org/10.1255/jnirs.1202 7. M. Vohland, M. Ludwig, M. Harbich, C. Emmerling and S. Thiele-Bruhn, “Using variable selection and wavelets to exploit the full potential of visible–near infrared spectra for predicting soil properties”, J. Near Infrared Spectrosc. 24, 255 (2016). doi: http://dx.doi.org/10.1255/jnirs.1233 8. M.H. Todorova and S.L. Atanassova, “Near infrared spectra and soft independent modelling of class analogy for discrimination of Chernozems, Luvisols and Vertisols”, J. Near Infrared Spectrosc. 24, 271 (2016). doi: http://dx.doi.org/10.1255/jnirs.1223 9. M. Paradelo, C. Hermansen, M. Knadel, P. Moldrup, M.H. Greve and L.W. de Jonge, “Field-scale predictions of soil contaminant sorption using visible–near infrared spectroscopy”, J. Near Infrared Spectrosc. 24, 281 (2016). doi: http://dx.doi.org/10.1255/jnirs.1228 10. A.M. de Souza, P.R. Filgueiras, M.R. Coelho, A. Fontana, T.C.B. Winkler, P. Valderrama and R.J. Poppi, “Validation of the near infrared spectroscopy method for determining soil organic carbon by employing a proficiency assay for fertility laboratories”, J. Near Infrared Spectrosc. 24, 293 (2016). doi: http://dx.doi.org/10.1255/jnirs.1219 11. E. Pérez-Fernández and A.H.J. Robertson, “Global and local calibrations to predict chemical and physical properties of a national spatial dataset of Scottish soils from their near infrared spectra”, J. Near Infrared Spectrosc. 24, 305 (2016). doi: http://dx.doi.org/10.1255/jnirs.1229 12. R.A. Viscarra Rossel, T. Behrens, E. Ben-Dor, D.J. Brown, J.A.M. Dematte, K.D. Shepherd, Z. Shi, B. Stenberg, A. Stevens, V.A. Adamchuk, H. Aichi, B.G. Barthes, H.M. Bartholomeus, A.D. Bayer, M. Bernoux, K. Bottcher, L. Brodsky, C.W. Du, A. Chappell, Y. Fouad, V. Genot, C. Gomez, S. Grunwald, A. Gubler, C. Guerrero, C.B. Hedley, M. Knadel, H.J.M. Morras, M. Nocita, L. Ramirez-Lopez, P. Roudier, E.M. Rufasto Campos, P. Sanborn, V.M. Sellitto, K.A. Sudduth, B.G. Rawlins, C. Walter, L.A. Winowiecki, S.Y. Hong and W. Ji, “A global spectral library to characterize the world’s soil”, EarthSci. Rev. 155, 198 (2016). doi: http://dx.doi.org/10.1016/j. earscirev.2016.01.012
