Session 1: Sequestration

“Time matters” - biochar persistence in soil and its effects on SOC stocks

From the start of biochar research, the value of biochar has been seen in its ability to allocate carbon from the fast biogeochemical cycle to slower cycling which was often termed “C sequestration”. This ability is intimately linked to the persistence and fate of biochar-C in soils (mineralization, particle disintegration, vertical transport etc.).
Moreover, there is an on-going debate on whether the use of biochar may or may not stimulate the mineralization of already existing soil organic carbon in either mineral or organic soils. On the other hand old soils with a high content of pyrogenic C may have larger SOC pools after decades or centuries, i.e. adding biochar may (or may not) result in a “return of investment” buildup of SOC on top of the pure biochar addition. Which one is true, and how can we predict what will happen?

Therefore Session 1 aims at addressing the following questions:

1)     How can we describe, test and predict biochar stability, depending on its properties (feedstock, production conditions)?

2)     Is there a general agreement on the question of priming and C loss after biochar addition? If so, how can we predict priming from the properties of the biochar-soil combination?

3)     Can we expect a longer-term SOC buildup in soils as “return of investment” e.g. after a phase of initial SOC priming? If yes, what is the mechanism(s), and how can we increase it towards C retention by modifying biochar properties?


Session lead:      Saran Sohi, UK Biochar Research Centre (UKBRC), Edinburgh, UK; Bruno Glaser, University Halle, Germany; Heike Knicker, CSIC Sevilla

Keynote: Yakov Kuzyakov


Lecture Title: Biochar stability in soil: Experiments, meta-analysis and consequences for carbon sequestration

Content: Results of 10 years old experiment to decomposition of 14C labeled biochar in soil will be presented and integrated with meta-analysis of biochar decomposition studies. Consequences for the improvement of soil fertility and carbon sequenstration will be discussed.

Dr. Yakov Kuzyakov, Dept. of Soil Science of Temperate Ecosystems and Dept. of Agricultural Soil Science, Georg-August-University of Göttingen, Germany; Soil biogeochemistry with strong focus on application of C and N isotopic approaches for investigation of terrestrial C and N cycles in soil-plant-microorganisms system


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