{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,13]],"date-time":"2026-03-13T23:13:03Z","timestamp":1773443583665,"version":"3.50.1"},"reference-count":73,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2021,2,18]],"date-time":"2021-02-18T00:00:00Z","timestamp":1613606400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Near-infrared reflectance spectroscopy (NIRS) was successfully used in this study to measure soil properties, mainly C and N, requiring spectral pre-treatments. Calculations in this evaluation were carried out using multivariate statistical procedures with preceding pre-treatment procedures of the spectral data. Such transformations could remove noise, highlight features, and extract essential wavelengths for quantitative predictions. This frequently significantly improved the predictions. Since selecting the appropriate transformation was not straightforward due to the large numbers of available methods, more comprehensive insight into choosing appropriate and optimized pre-treatments was required. Therefore, the objectives of this study were (i) to compare various pre-processing transformations of spectral data to determine their suitability for modeling soil C and N using NIR spectra (55 pre-treatment procedures were tested), and (ii) to determine which wavelengths were most important for the prediction of C and N. The investigations were carried out on an arable field in South Germany with a soil type of Calcaric Fluvic Relictigleyic Phaeozem (Epigeoabruptic and Pantoclayic), created in the flooding area of the Isar River. The best fit and highest model accuracy for the C (Ct, Corg, and Ccarb) and N models in the calibration and validation modes were achieved using derivations with Savitzky\u2013Golay (SG). This enabled us to calculate the Ct, Corg, and N with an R2 higher than 0.98\/0.86 and an ratio of performance to the interquartile range (RPIQ) higher than 10.9\/4.1 (calibration\/validation).<\/jats:p>","DOI":"10.3390\/s21041423","type":"journal-article","created":{"date-parts":[[2021,2,18]],"date-time":"2021-02-18T21:59:58Z","timestamp":1613685598000},"page":"1423","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":56,"title":["An Evaluation of Different NIR-Spectral Pre-Treatments to Derive the Soil Parameters C and N of a Humus-Clay-Rich Soil"],"prefix":"10.3390","volume":"21","author":[{"given":"Kurt","family":"Heil","sequence":"first","affiliation":[{"name":"Chair of Plant Nutrition, Technical University Munich, Emil-Ramann-Str. 2, D-85350 Freising, Germany"},{"name":"Chair of Agricultural Systems Engineering, Technical University Munich, D\u00fcrnast 4, D-85354 Freising, Germany"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4106-7124","authenticated-orcid":false,"given":"Urs","family":"Schmidhalter","sequence":"additional","affiliation":[{"name":"Chair of Plant Nutrition, Technical University Munich, Emil-Ramann-Str. 2, D-85350 Freising, Germany"}]}],"member":"1968","published-online":{"date-parts":[[2021,2,18]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"480","DOI":"10.2136\/sssaj2001.652480x","article-title":"Near-Infrared reflectance spectroscopy-principal components regression analyses of soil properties","volume":"65","author":"Chang","year":"2001","journal-title":"Soil Sci. Soc. Am. J."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"59","DOI":"10.1016\/j.geoderma.2005.03.007","article-title":"Visible, near infrared, mid infrared or combined diffuse reflectance spectroscopy for simultaneous assessment of various soil properties","volume":"131","author":"Walvoortb","year":"2006","journal-title":"Geoderma"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"403","DOI":"10.1016\/j.geoderma.2008.06.011","article-title":"Soil organic carbon prediction by hyperspectral remote sensing andfield vis-NIRspectroscopy: An Australian case study","volume":"146","author":"Gomez","year":"2008","journal-title":"Geoderma"},{"key":"ref_4","first-page":"859","article-title":"Visible and near infrared reflectance spectroscopy to determine chemical properties of paddy soils","volume":"11","author":"Boruvka","year":"2013","journal-title":"J. Food Agric. Environ."},{"key":"ref_5","unstructured":"Gholizadeh, A., Bor\u016fvka, L., and Saberioon, M. (2013, January 4\u20136). Common Chemometric Indicators for Prediction of Soil Organic Matter Content and Quality from Soil Spectra: A Review and Research Perspectives. Proceedings of the International Workshop \u201cSoil Spectroscopy: The Present and Future of Soil Monitoring\u201d, Rome, Italy."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1349","DOI":"10.1366\/13-07288","article-title":"Visible, near-infrared, and mid-infrared spec-troscopy applications for soil assessment with emphasis on soil organic matter content and quality: State-of-the-art and key issues","volume":"67","author":"Gholizadeh","year":"2013","journal-title":"Appl. Spectrosc."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"988","DOI":"10.2136\/sssaj2002.9880","article-title":"Development of reflectance spectra libraries for characterization of soil properties","volume":"66","author":"Shepherd","year":"2002","journal-title":"Soil Sci. Soc. Am. J."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"179","DOI":"10.1255\/jnirs.248","article-title":"Near infrared reflectance spectroscopy for the analysis of agricultural soils","volume":"7","author":"Reeves","year":"1999","journal-title":"J. Near Infrared Spectrosc."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"193","DOI":"10.1016\/j.geoderma.2004.09.013","article-title":"Near infrared reflectance spectroscopy for assessment of spatial soil variation in an agricultural field","volume":"126","author":"Odlare","year":"2005","journal-title":"Geoderma"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"78","DOI":"10.1016\/j.still.2004.12.006","article-title":"Potential of near-infrared reflectance spectroscopy and chemometrics to predict soil organic carbon fractions","volume":"85","author":"Cozzolino","year":"2006","journal-title":"Soil Till. Res."},{"key":"ref_11","first-page":"215","article-title":"Global soil characterization with VNIR diffuse reflectance spectroscopy","volume":"129","author":"Brown","year":"2005","journal-title":"Geoderma"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"305","DOI":"10.1016\/j.biosystemseng.2005.04.015","article-title":"Spectral phosphorus mapping using diffuse reflectance of soils and grass","volume":"91","author":"Bogrecki","year":"2005","journal-title":"Biosyst. Eng."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1403","DOI":"10.1177\/0003702817709299","article-title":"A Review of the Principles and Applications of Near-Infrared Spectroscopy to Characterize Meat, Fat, and Meat Products","volume":"71","author":"Aalhus","year":"2017","journal-title":"Appl. Spectr."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"14","DOI":"10.1016\/j.geoderma.2008.04.007","article-title":"Comparison of multivariate methods for. inferential modeling of soil carbon using visible-near infrared spectra","volume":"146","author":"Vasques","year":"2008","journal-title":"Geoderma"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"176","DOI":"10.2136\/sssaj2008.0015","article-title":"Modeling of Soil Organic Carbon Fractions Using Visible\u2013Near-Infrared Spectroscopy","volume":"73","author":"Vasques","year":"2009","journal-title":"Soil Sci. Soc. Am. J."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"351","DOI":"10.1016\/S1002-0160(12)60022-8","article-title":"Visible and Near-Infrared Diffuse Reflectance Spectroscopy for Prediction of Soil Properties near a Copper Smelter","volume":"22","author":"Xie","year":"2012","journal-title":"Pedosphere"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"262","DOI":"10.1016\/j.geoderma.2017.11.006","article-title":"A systematic study on the application of scatter-corrective and spectralderivative pre-processing for multivariate. prediction of soil organic carbon by Vis-NIR spectra","volume":"314","author":"Dotto","year":"2018","journal-title":"Geoderma"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1627","DOI":"10.1021\/ac60214a047","article-title":"Smoothing and differentiation of data by simplified least squares procedures","volume":"36","author":"Savitzky","year":"1964","journal-title":"Anal. Chem."},{"key":"ref_19","first-page":"115","article-title":"Mathematical Data Preprocessing","volume":"Volume 44","author":"Roberts","year":"2004","journal-title":"Near-Infrared Spectroscopy in Agriculture"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1201","DOI":"10.1016\/j.trac.2009.07.007","article-title":"Review of the most common pre-processing techniques for near-infrared spectra","volume":"28","author":"Rinnan","year":"2009","journal-title":"TrAC Trends Anal. Chem."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"202","DOI":"10.1016\/j.geoderma.2010.12.020","article-title":"Comparison of soil reflectance spectra and calibration models obtained using multiple spectrometers","volume":"161","author":"Ge","year":"2011","journal-title":"Geoderma"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"41","DOI":"10.1016\/j.geoderma.2012.03.011","article-title":"Building a near infrared spectral library for soil organic carbon estimation in the Limpopo National Park, Mozambique","volume":"183\u2013184","author":"Cambule","year":"2012","journal-title":"Geoderma"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"59","DOI":"10.1016\/j.still.2017.05.008","article-title":"Two pre-processing techniques to reduce model covariables in soil property predictions by Vis-NIR spectroscopyd","volume":"172","author":"Dotto","year":"2017","journal-title":"Soil Tillage Res."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"312","DOI":"10.1016\/j.geoderma.2012.06.009","article-title":"Soil total carbon analysis in Hawaiian soils with visible, near-infrared and mid-infrared diffuse reflectance spectroscopy","volume":"189\u2013190","author":"McDowell","year":"2012","journal-title":"Geoderma"},{"key":"ref_25","first-page":"294121","article-title":"Effects of subsetting bycarbon content, soil order, and spectral classification on prediction of soil total carbonwith diffuse reflectance spectroscopy","volume":"2012","author":"McDowell","year":"2012","journal-title":"J. Appl. Environ. Soil Sci."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"2699","DOI":"10.3390\/rs6042699","article-title":"Estimating soil organic carbon using VIS\/NIR spectroscopy with SVMR and SPA methods","volume":"6","author":"Peng","year":"2014","journal-title":"Remote Sens."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1026","DOI":"10.1002\/ldr.3497","article-title":"Monitoring soil organic carbon in alpine soils using in situ vis-NIR spectroscopy and a multilayer perceptron","volume":"31","author":"Chen","year":"2020","journal-title":"Land Degrad Dev."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1371\/journal.pone.0117457","article-title":"Estimation of Potentially Toxic Elements Contamination in Anthropogenic Soils on a Brown Coal Mining Dumpsite by Reflectance Spectroscopy:A Case Study","volume":"10","author":"Gholizadeh","year":"2015","journal-title":"PLoS ONE"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"229","DOI":"10.1016\/j.geoderma.2014.10.019","article-title":"Modelling soil carbon fractions with visible near-infrared (VNIR) and mid-infrared (MIR) spectroscopy","volume":"239\u2013240","author":"Knox","year":"2015","journal-title":"Geoderma"},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Pinheiro, E., Ceddia, M., Clingensmith, C.M., Grunwald, S., and Vasques, G.M. (2017). Prediction of Soil Physical and Chemical Properties by Visible and Near-Infrared Diffuse Reflectance Spectroscopy in the Central Amazon. Remote Sens., 9.","DOI":"10.3390\/rs9040293"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"510","DOI":"10.1016\/j.still.2015.07.021","article-title":"Estimating the soil clay content and organic matter by means of different calibration methods of Vis-NIR diffuse reflectance spectroscopy","volume":"155","author":"Nawar","year":"2016","journal-title":"Soil Tillage Res."},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Peng, Y., Zhao, L., Hu, Y., Wang, G., Wang, l., and Liu, Z. (2019). Prediction of Soil Nutrient Contents Using Visible and Near-Infrared Reflectance Spectroscopy. Isprs Int. J. Geo Inf., 8.","DOI":"10.3390\/ijgi8100437"},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Wang, X., Shi, A., Yaqing, X., Huping, H., Fuyao, C., Yongjun, Y., Shaoliang, Z., and Run, L. (2020). A Back Propagation Neural Network Model Optimized by Mind Evolutionary Algorithm for Estimating Cd, Cr, and Pb Concentrations in Soils Using Vis-NIR Diffuse Reflectance Spectroscopy. Appl. Sci., 10.","DOI":"10.3390\/app10010051"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"102","DOI":"10.1016\/j.geoderma.2011.07.017","article-title":"Soil carbon mapping using on-the-go near infrared spectroscopy, topography and aerial photographs","volume":"166","author":"Kravchenko","year":"2011","journal-title":"Geoderma"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1371\/journal.pone.0066409","article-title":"Prediction of soil organic carbon at the European scale by visible and near InfraRed reflectance spectroscopy","volume":"8","author":"Stevens","year":"2013","journal-title":"PLoS ONE"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"72","DOI":"10.1016\/j.tifs.2006.09.003","article-title":"Theory and Application of near Infrared Reflectance Spectroscopy in. Determination of Food Quality","volume":"18","author":"Cen","year":"2007","journal-title":"Trends Food Sci. Technol."},{"key":"ref_37","unstructured":"(2021, February 18). Bodenkundliche Kartieranleitung. 5. Verbesserte und 540 Erweiterte Auflage. Schweizerbart\u2019sche Verlagsbuchhandlung: Hannover, Germany. Available online: https:\/\/www.schweizerbart.de\/publications\/detail\/artno\/184050681."},{"key":"ref_38","unstructured":"VDLUFA (2021, February 18). Methode C 2.2.1, Texturanalyse des Feinbodens Kombination von Nasssiebung und Pipettmethode nach K\u00d6HN. Available online: https:\/\/www.vdlufa.de\/Methodenbuch\/index.php?option=com_content&view=article&id=7&Itemid=108&lang=de&lang=en."},{"key":"ref_39","unstructured":"CAMO (2019, October 10). The Unscrambler User Manual Camo Software AS. Manual is up to Date for Version 9.6 of The Unscrambler. Available online: www.camo.com\/downloads\/products\/The_Unscrambler.pdf."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"1969","DOI":"10.1016\/j.scitotenv.2018.09.391","article-title":"Estimating lead and zinc concentrations in peri-urban agricultural soils through reflectance spectroscopy: Effects of fractional-order derivative and random forest","volume":"651","author":"Hong","year":"2019","journal-title":"Sci. Total Environ."},{"key":"ref_41","doi-asserted-by":"crossref","unstructured":"Roberts, C.A., Workman, J., and Reeves, J.B. (2004). Quantitative Analysis. Agronomy Monographs, Soil Science Society of America, Inc.. Chapter 7.","DOI":"10.2134\/agronmonogr44"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1071\/SR07099","article-title":"Using a legacy soil sample to develop a mid-IR spectral library","volume":"46","author":"Jeon","year":"2008","journal-title":"Austral. J. Soil Res."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"22","DOI":"10.1255\/nirn.1419","article-title":"Tutorial: The RPD Statistic: A Tutorial Note","volume":"25","author":"Williams","year":"2014","journal-title":"NIR News"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"1073","DOI":"10.1016\/j.trac.2010.05.006","article-title":"Critical review of chemometric indicators commonly used for assessing the quality of the prediction of soil attributes by NIR spectroscopy","volume":"29","author":"Palagos","year":"2010","journal-title":"TrAC Trends Anal. Chem."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"8","DOI":"10.1016\/j.geoderma.2016.11.013","article-title":"Chemometric soil analysis on the determination of specific bands for the detection of magnesium and potassium by spectroscopy","volume":"288","author":"Marques","year":"2017","journal-title":"Geoderma"},{"key":"ref_46","doi-asserted-by":"crossref","unstructured":"Viscarra Rossel, R.A., McBratney, B.A., and Minasny, B. (2010). Diffuse reflectance spectroscopy for high resolution soil sensing. Proximal Soil Sensing, Springer Science + Business.","DOI":"10.1007\/978-90-481-8859-8"},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"163","DOI":"10.1016\/S0065-2113(10)07005-7","article-title":"Visible and Near Infrared Spectroscopy in Soil Science","volume":"Volume 107","author":"Sparks","year":"2010","journal-title":"Advances in Agronomy"},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"535","DOI":"10.1016\/j.rse.2003.11.009","article-title":"Predicting water content using Gaussian model on soil spectra","volume":"89","author":"Whiting","year":"2004","journal-title":"Remote Sens. Environ."},{"key":"ref_49","first-page":"3","article-title":"Spectroscopy of rocks and minerals, and principles of spectroscopy","volume":"3","author":"Clark","year":"1999","journal-title":"Manual Remote Sens."},{"key":"ref_50","doi-asserted-by":"crossref","unstructured":"Thenkabail, P.S., Lyon, J.G., and Huete, A. (2011). Characterization of soil properties using reflectance spectroscopy. Hyperspectral Remote Sensing of Vegetation, Crc Press.","DOI":"10.1201\/b11222-41"},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"1778","DOI":"10.2136\/sssaj1989.03615995005300060028x","article-title":"Spectral band selection from classification of soil organic matter content","volume":"53","author":"Henderson","year":"1989","journal-title":"Soil Sci. Soc. Am. J."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"394","DOI":"10.1021\/ac020194w","article-title":"Light Scattering and Light Absorbance Separated by Extended Multiplicative Signal Correction. Application to Near-Infrared Transmission Analysis of Powder Mixtures","volume":"75","author":"Martens","year":"2003","journal-title":"Anal. Chem."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"75","DOI":"10.1002\/cem.1274","article-title":"Local chemometrics for samples and variables: Optimizing calibration and standardizationprocesses","volume":"24","author":"Igne","year":"2010","journal-title":"J. Chemom."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"453","DOI":"10.1111\/j.1365-2389.2009.01121.x","article-title":"Improved analysis and modelling of soil diffuse reflectance spectra using wavelets","volume":"60","author":"Lark","year":"2009","journal-title":"Eur. J. Soil Sci."},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"772","DOI":"10.1366\/0003702894202201","article-title":"Standard Normal Variate Transformation and De- Trending of near-Infrared Diffuse Reflectance Spectra","volume":"43","author":"Barnes","year":"1989","journal-title":"Appl. Spectrosc."},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"22","DOI":"10.1016\/j.geoderma.2011.05.006","article-title":"Comparison and detection of total and available soil carbon fractions using visible\/near infrared diffuse reflectance spectroscopy","volume":"164","author":"Sarkhot","year":"2011","journal-title":"Geoderma"},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"122","DOI":"10.1016\/j.biombioe.2012.02.015","article-title":"Total and available soil carbon fractions under the perennial grass Cynodon dactylon (L.) Pers and the bioenergy crop Arundo donax L.","volume":"41","author":"Sarkhot","year":"2012","journal-title":"Biomass Bioenergy"},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"277","DOI":"10.1016\/S0269-7491(01)00259-7","article-title":"The potential of diffuse reflectance spectroscopy for the determination of carbon inventories in soils","volume":"116","author":"McCarty","year":"2002","journal-title":"Environ. Pollut."},{"key":"ref_59","doi-asserted-by":"crossref","first-page":"46","DOI":"10.1016\/j.geoderma.2009.12.025","article-title":"Using data mining to model and interpret soil diffuse reflectance spectra","volume":"158","author":"Behrens","year":"2010","journal-title":"Geoderma"},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"1101","DOI":"10.1071\/SR02137","article-title":"Simultaneous estimation of several soil properties by ultra- violet, visible, and near-infrared reflectance spectroscopy","volume":"41","author":"Islam","year":"2003","journal-title":"Soil Res."},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"139","DOI":"10.1023\/A:1020612319014","article-title":"The prediction of C and N content and their potential mineralisation in heterogeneous soil samples using Vis\u2013NIR spectroscopy and comparative methods","volume":"246","author":"Fystro","year":"2002","journal-title":"Plant Soil"},{"key":"ref_62","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1071\/EA01172","article-title":"The potential of near infrared reflectance spectroscopy for soil analysis-a case study from the Riverine Plain of South Eastern Australia","volume":"42","author":"Dunn","year":"2002","journal-title":"Aust. J. Exp. Agric."},{"key":"ref_63","doi-asserted-by":"crossref","first-page":"149","DOI":"10.1016\/S0168-1699(01)00163-6","article-title":"Soil moisture and organic matter prediction of surface and subsurface soils using an NIR soil sensor","volume":"32","author":"Hummel","year":"2001","journal-title":"Comput. Electron. Agric."},{"key":"ref_64","doi-asserted-by":"crossref","first-page":"1398","DOI":"10.1016\/j.soilbio.2011.02.019","article-title":"Near-infrared (NIR) and mid-infrared (MIR) spectroscopic techniques for assessing the amount of carbon stock in soils\u2014Critical review and research perspectives","volume":"43","author":"McBratney","year":"2011","journal-title":"Soil Biol. Biochem."},{"key":"ref_65","doi-asserted-by":"crossref","first-page":"364","DOI":"10.2136\/sssaj1995.03615995005900020014x","article-title":"Near-Infrared Analysis as a Rapid Method to Simultaneously Evaluate. Several Soil Properties","volume":"59","author":"Banin","year":"1995","journal-title":"Soil Sci. Soc. Am. J."},{"key":"ref_66","doi-asserted-by":"crossref","first-page":"415","DOI":"10.1023\/A:1008151421747","article-title":"Determination of carbon, carbonate, nitrogen, and phosphorus in freshwater sediments by near-infrared reflectance spectroscopy: Rapid analysis and a check on conventional analytical methods","volume":"24","author":"Malley","year":"2000","journal-title":"J. Paleolimnol."},{"key":"ref_67","doi-asserted-by":"crossref","first-page":"288","DOI":"10.2136\/sssaj1991.03615995005500010051x","article-title":"Carbon and Nitrogen Analysis of Soil Fractions Using. Near-Infrared Reflectance Spectroscopy","volume":"55","author":"Morra","year":"1991","journal-title":"Soil Sci. Soc. Am. J."},{"key":"ref_68","doi-asserted-by":"crossref","first-page":"249","DOI":"10.1016\/j.geoderma.2009.04.010","article-title":"Simulated in situ characterization of soil organic and inorganic carbon with visible near-infrared diffuse reflectance spectroscopy","volume":"151","author":"Morgan","year":"2009","journal-title":"Geoderma"},{"key":"ref_69","doi-asserted-by":"crossref","first-page":"13","DOI":"10.1016\/j.still.2006.03.009","article-title":"On-line measurement of some selected soil properties using a VIS\u2013NIR sensor","volume":"93","author":"Mouazen","year":"2007","journal-title":"Soil Tillage Res."},{"key":"ref_70","doi-asserted-by":"crossref","first-page":"1282","DOI":"10.2136\/sssaj1980.03615995004400060030x","article-title":"Reflectance technique for predicting soil organic matter","volume":"44","author":"Kirshnan","year":"1980","journal-title":"Soil Sci. Soc. Am. J."},{"key":"ref_71","doi-asserted-by":"crossref","first-page":"629","DOI":"10.1111\/j.1365-2389.2011.01358.x","article-title":"Calibration of visible and near infrared spectroscopy for soil analysis at the field scale on three European farms","volume":"62","author":"Kuang","year":"2011","journal-title":"Eur. J. Soil Sci."},{"key":"ref_72","first-page":"171","article-title":"Mapping soil organic matter based on land 651 degradation spectral response units using Hyperion images","volume":"652","author":"Wang","year":"2010","journal-title":"Int. J. Appl. Earth Obs. Geoinf."},{"key":"ref_73","doi-asserted-by":"crossref","unstructured":"Kawamura, K., Tsujimoto, Y., Nishigaki, T., Andriamanajara, A., Rabenarivo, M., Asai, H., Rakotoson, T., and Razafimbelo, T. (2019). Laboratory visible and near-infrared spectroscopy with genetic algorithm-based partial least squares regression for assessing the soil phosphorus content of upland and lowland rice fields in Madagascar. Remote Sens., 11.","DOI":"10.3390\/rs11050506"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/4\/1423\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T05:25:41Z","timestamp":1760160341000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/4\/1423"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,2,18]]},"references-count":73,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2021,2]]}},"alternative-id":["s21041423"],"URL":"https:\/\/doi.org\/10.3390\/s21041423","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,2,18]]}}}