Allory V., Cambou A., Moulin Esmard Patricia, Schwartz C., Cannavo P., Vidal-Beaudet L., Barthès Bernard. (2019). Quantification of soil organic carbon stock in urban soils using visible and near infrared reflectance spectroscopy (VNIRS) in situ or in laboratory conditions. Science of the Total Environment, 686, p. 764-773. ISSN 0048-9697.
Titre du document
Quantification of soil organic carbon stock in urban soils using visible and near infrared reflectance spectroscopy (VNIRS) in situ or in laboratory conditions
Année de publication
Allory V., Cambou A., Moulin Esmard Patricia, Schwartz C., Cannavo P., Vidal-Beaudet L., Barthès Bernard
Science of the Total Environment, 2019,
686, p. 764-773 ISSN 0048-9697
Urban soils, like other soils, can be sink or source for atmospheric carbon dioxide, and due to urban expansion, are receiving increasing attention. Studying their highly variable attributes requires high-density sampling, which can hardly be achieved using conventional approaches. The objective of this work was to determine the ability of visible and near infrared reflectance spectroscopy (VNIRS) to quantify soil organic carbon (SOC) concentration (gC kg(-1)) and stock (gC dm(-3), or MgC ha(-1) for a given depth layer) in parks and sealed soils of two French cities, Marseille and Nantes, using spectra collected on pit walls or in laboratory conditions (air dried, 2 mm sieved samples). Better VNIRS predictions were achieved using laboratory than in situ spectra (R-2 approximate to 0.8-0.9 vs. 0.7-0.8 in validation), and for sample SOC concentration than stock (R-vai(2) up to 0.83 in situ and 0.95 in the laboratory vs. 0.78 and 0.89, respectively). Stock was conventionally calculated according to four methods that variably account for coarse particles (>2 mm); and it was better predicted when coarse particles were not taken into account. This was logical using laboratory spectra, collected on 2 mm sieved samples; but concerning in situ spectra, this suggested the operator tended to put the spectrometer beside the coarsest particles during spectrum acquisition. This point is worth considering for urban soils, often rich in coarse particles. Stocks were then aggregated at the profile level: SOC stock prediction was more accurate at profile than sample level when using laboratory spectra (R-vai(2) = 0.94 vs. 0.89, respectively), probably due to uncertainty compensation; but this was not the case when using in situ spectra, possibly because samples collected for SOC analysis and corresponding VNIRS scans were not at the exact same location. This work demonstrates VNIRS usefulness for quantifying SOC stock time- and cost-effectively, in urban soils especially.
Plan de classement
Urbanisation et sociétés urbaines 
FRANCE ; MARSEILLE ; NANTES
Fonds IRD [F B010076559]