Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8362977 | Soil Biology and Biochemistry | 2018 | 6 Pages |
Abstract
Organo-mineral interactions control the stabilisation of soil organic matter (SOM) in mineral soils. Biochar can enhance these interactions via a range of mechanisms including Al-dominant cation bridging in acidic soils, ligand exchange, H-bonding, and Ï- Ï-bonding with polycyclic aromatics. But, field-based evidence of their magnitude is lacking. Here we assessed the role of organo-mineral interactions on the observed biochar-induced negative priming of native soil organic carbon (SOC) in a Ferralsol under annual ryegrass. Using repeated pulse labelling, the magnitude of production and fate of recently photosynthesised 13C was traced amongst: soil plus root respiration, root biomass, soil aggregates and aggregate-associated C fractions. Biochar (Eucalyptus saligna, 450â¯Â°C) amendment (30â¯Mgâ¯haâ1) increased total belowground 13C recovery by 10% compared to the unamended control over the 12 month sampling period. We detected the greatest quantity of rhizodeposit in the mineral-protected SOM within macroaggregates (250-2000â¯Î¼m). Through synchrotron-based spectroscopic analysis of bulk soils, we provide evidence of a mechanism for biochar-induced negative priming which is the accumulation of rhizodeposits in organo-mineral (i.e. aggregate-protected and silt/clay-bound) fractions.
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Authors
Zhe (Han) Weng, Lukas Van Zwieten, Bhupinder Pal Singh, Ehsan Tavakkoli, Stephen Kimber, Stephen Morris, Lynne M. Macdonald, Annette Cowie,