Journal of Soils and Sediments

, Volume 18, Issue 4, pp 1389–1399 | Cite as

New methodology to assess the quantity and quality of humic substances in organic materials and commercial products for agriculture

  • Marta Fuentes
  • Roberto Baigorri
  • Gustavo González-Gaitano
  • José María García-Mina
Natural Organic Matter: Chemistry, Function and Fate in the Environment



The traditional method to determine humic content (humic and fulvic acids) in commercial fertilizers, biostimulants, and organic materials is based on the oxidation of the organic carbon contained in the basic-soluble but acid-insoluble fraction (humic acids) and the basic-acid soluble fraction (fulvic acids) of their alkaline water extracts. This methodology, merely operational, makes it impossible to distinguish if the quantified carbon corresponds to substances with “humic” chemical nature or to non-humic organic matter but with similar solubility properties to those of humic matter. The aim of this work is to develop a new methodology that not only quantifies the humic content in commercial products (and raw materials) but also assesses the humic quality of the quantified organic matter.

Materials and methods

To this end, humic and fulvic (-like) fractions have been isolated/purified from several humic and non-humic materials and characterized by means of elemental analysis and UV-visible, fluorescence, and infrared spectroscopies, and these data have been used to perform a discriminant analysis (DA).

Results and discussion

The model obtained from the DA is able to discriminate humic and fulvic fractions from apparently humic or fulvic ones and provides discriminant classification functions that have proven to successfully predict the “humic quality” of the fractions isolated from commercial products, after their elemental and spectroscopic characterization.


Therefore, the combination of the fractionation, characterization, and evaluation by the DA is proposed as an effective methodology for quantifying and assessing the quality of the humic content claimed in the labels of commercial products.


Agricultural products Biostimulants Fulvic acids Humic acids Humic quantification Humic substances Humification Organic carbon Organic matter 

Supplementary material

11368_2016_1514_MOESM1_ESM.doc (995 kb)
ESM 1 (DOC 995 kb)


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Copyright information

© Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  1. 1.Department of Environmental Biology, Biological and Agricultural Chemistry Group (BACh)University of NavarraPamplonaSpain
  2. 2.Department of ChemistryUniversity of NavarraPamplonaSpain
  3. 3.Technical and Development DepartmentTimac Agro EspañaLodosaSpain

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