Impact of lignite on pedogenetic processes and microbial functions in Mediterranean soils

• Published in: Geoderma 2014-11, Vol.232-234, p.257-269
• Main Authors: Clouard, M., Criquet, S., Borschneck, D., Ziarelli, F., Marzaioli, F., Balesdent, J., Keller, C.
• Format: Article
• Language: English
• Subjects: 14C dating; Agronomy. Soil science and plant productions; Basal respiration; Biological and medical sciences; Brown coal; Carbon; Continental interfaces, environment; Earth sciences; Earth, ocean, space; Enzymatic activities; Exact sciences and technology; Fluorescein; Fundamental and applied biological sciences. Psychology; Horizon; Lignite; Microorganisms; Mineralogy; Sciences of the Universe; Signatures; Soils; SS 13C CPMAS NMR; Surficial geology
• ISSN: 0016-7061; 1872-6259
• DOI: 10.1016/j.geoderma.2014.05.009

We compared a calcareous soil developed from a lignite vein (natural outcrop) and a control adjacent soil without lignite in order to assess the impact of lignite on pedogenetic processes and microbial functions in Mediterranean soils. Lignite was evidenced by the 14C analysis, δ13C signature and SS 13C CPMAS NMR spectroscopy in the various soil horizons. Physico-chemical (particle size analysis, pH, total organic carbon, carbonate content, nitrogen, sulfur, cation exchange capacity, crystalline and amorphous Fe and Al, mineralogy, bulk density) and biological (enzyme activities: β-glucosidase, arylsulfatase, acid phosphatase, arylamidase, fluorescein dilaurate hydrolase and fluorescein diacetate hydrolase; basal respiration and Biolog ® catabolic profile) properties were also analyzed in all horizons. We showed that the naturally-occurring lignite modified soil organic matter quality and mineralogy and improved some soil properties such as clay content, Corg, CEC and porosity. On the contrary, lignite had a higher C/N and higher recalcitrant C content compared to recent soil organic matter, which resulted in a decrease in the expression of microbial soil functions involved in the turn-over of the main bio-elements C, N, P and S due to lignite acting as a diluting factor (i.e. inert regarding microbial activities). The information derived from this study offers insight on the long term fate of lignite in soil, especially relevant if lignite is aimed at being used as amendment. •Impact of naturally-occurring lignite on Mediterranean soil characteristics•Evidence of lignite in the soil is assessed by combined approaches.•Lignite influences positively the physico-chemical characteristics on the long-term.•Lignite appears inert regarding microbial activity on the long-term.