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Historical soil amendment with charcoal increases sequestration of non‐charcoal carbon: a comparison among methods of black carbon quantification
Author(s) -
Kerré B.,
Bravo C. T.,
Leifeld J.,
Cornelissen G.,
Smolders E.
Publication year - 2016
Publication title -
european journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 1351-0754
DOI - 10.1111/ejss.12338
Subject(s) - charcoal , carbon black , soil carbon , total organic carbon , chemistry , environmental chemistry , amendment , carbon sequestration , biochar , carbon fibers , organic matter , soil test , soil organic matter , soil water , environmental science , soil science , carbon dioxide , materials science , pyrolysis , organic chemistry , natural rubber , composite number , political science , law , composite material
We have shown previously that soil with historical (> 150 years) applications of charcoal had larger recent ( C4 ‐maize derived) carbon content than adjacent soil; however, we could not determine whether there was an effect on older, C3 ‐plant‐derived, soil organic carbon ( SOC ). Therefore, we assessed the effect of historical additions of charcoal on the sequestration of recent and older SOC with a combination of δ 13 C analysis and different quantification techniques for black carbon ( BC ): dichromate oxidation ( Cr 2 O 7 ), chemo‐thermal oxidation ( CTO ‐285) and differential scanning calorimetry ( DSC ). Topsoils cropped with maize ( Zea mays ) under former charcoal production sites ( N = 12) were identified in the field as black spots and had a larger (3.5%, P < 0.05) percentage of organic carbon ( OC ) contents than adjacent soil outside these spots (2.0%). The charcoal content varied with the detection technique used as follows: CTO ‐285 > DSC > Cr 2 O 7 . Black spots contained 1.6–1.7 times more ( P < 0.05) maize‐derived OC content than adjacent soil, irrespective of the BC quantification technique. The content of non‐charcoal OC was 1.0–1.4 times larger in black spots than in adjacent soil, but differences were significant only for the Cr 2 O 7 method. Soil physicochemical fractionation showed that at charcoal production sites more OC was recovered in the particulate organic matter and silt and clay fractions. The δ 13 C analysis suggested that additional maize‐ OC in black spots was in the physically more protected silt and clay fraction. Overall, this study shows that historical charcoal amendment in soil enhances the accumulation of recent maize‐derived OC in a temperate climate without replacing the older C stocks. Highlights We assessed the effect of historical additions of charcoal on the sequestration of recent and older SOC . Black spots contained 1.6–1.7 times more ( P < 0.05) maize‐derived OC content than adjacent soil. Additional maize‐ OC in black spots was in the physically more protected silt and clay fraction. Historical charcoal amendment in soil enhances the accumulation of recent maize‐derived OC .