Submitted to: Soil Science Society of America Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/19/2013
Publication Date: 2/21/2014
Citation: Nguyen, B.T., Koide, R.T., Drohan, P.J., Skinner, R.H., Dell, C.J., Adler, P.R., Nord, A.N. 2014. Turnover of soil carbon pools following addition of switchgrass-derived biochar to four soils. Soil Science Society of America Journal. 78:531-537. Interpretive Summary: Addition of biochar (the residual of the fast burning of plant biomass) to soil has the potential to sequester carbon and improve conditions for plant growth, but the impact of the biochar can depend on the type of plant material used. The decomposition rate switchgrass-dereived biochar, was determined in four marginally-productive soils that are currently being evaluated for their potential to grow switchgrass for biofuel feedstock. While there was a measurable effect of soil type on the rate of biochar decomposition, only a small percentage the biochar carbon was released from each of the soils. The study showed that the switchgrass-derived biochar can be expected to add to long-term carbon sequestration when applied to each of the tested soils.
Technical Abstract: The amendment of soils with biochar may improve plant growth and sequester carbon, especially in marginal soils not suitable for the majority of commodity production. While biochar can persist in soils, it is not clear whether its persistence is affected by soil type. Moreover, we know little of how native soil organic matter dynamics are affected by biochar. We set out to determine the effect of soil type on biochar C dynamics, and the effect of biochar amendment on native soil C turnover using four marginally productive soils, two that are poorly drained and two that are excessively drained. During a 189-day incubation we monitored carbon dioxide emissions from soils, pure switchgrass-derived biochar, and soils amended with biochar, and we partitioned the carbon dioxide as to its source. Mixture with soil increased the size of the labile biochar-C pool and the amount of carbon dioxide evolved from biochar. The mean residence times of both the labile and stable biochar-C pools were generally decreased in biochar amended soil, and the magnitude of change depended on the soil type. Biochar amendment had no significant effect on emission of carbon dioxide derived from native soil organic matter, irrespective of the soil type. Our results suggest for a laboratory setting that amendment of soils with switchgrass-derived biochar can increase net carbon sequestration, however, further studies are warranted to test whether a similar result is seen under field conditions.