Dr Saran Sohi

I was recruited to lead soil science research in the UK Biochar Research Centre, Edinburgh, at its inception in late 2008. I moved to Edinburgh in February 2009, and our Centre launched on April 1st.

The purpose of my work is to deliver UKBRC a sound mechanistic understanding of biochar function in soil, and gain from this the predictive capacity required to 'prescribe' biochar in ways that firstly are safe, and secondly offer the best possible results in terms of soil and crop performance at previously untested locations. The resolution and certainty of the understanding that we seek is driven by the need to assign financial value to biochar products reflecting (a) benefit to the agricultural enterprise, and (b) achievement of societal goals such as carbon storage, management of diffuse pollution, and mitigation of trace gas emission from agriculture. My work is inextricably linked to those of my colleagues who lead research into the optimising pyrolysis processes for the conversion of biomass into biochar, estimation of carbon-equivalent gains offered by pyrolysis-biochar systems, and scoping associated socio-economic issues including land-use.

The practical tools that we are currently developing are rapid assays for screening biochar according to five key functional properties in soil, and thus provide for the optimisation of their use performance in contrasting locations and circumstances. The dynamics as well as magnitude of product characteristics are being considered in this process, since it should be possible to manipulate the timescale over which benefits from biochar in soil are delivered, as well as their size. Simultaneously, the nature of the interactions between plant roots and biochar is being assessed using microcosms and triangulation with small scale field studies - in collaboration with Rothamsted Research I have instigated an isotope-tracer experiment that seeks to establish how the stabilisation of root-derived carbon (organic matter from root exudation) is affected by the presence of biochar.

We are thus in the initial stages of a strategic programme of research, where a set of novel screening tools will soon provide for a systematic evaluation of how alternate biomass conversion technologies, and sliding-scale for key process variables, dictates the biochar product. The knowledge that is gained here, combined with an understanding of how different plants interact with biochar (cereal crops, perennial grasses, bioenergy crops), will guide selection of products for use in trials. The later stages of our five-year programme will result in refinement and validation of our emerging, laboratory-derived understanding of biochar function in the field environment.

Soil Science research in UKBRC Edinburgh currently involves two post-doctoral researchers, a research scientist, and two PhD students. We are linked to a large network of national and international collaborations, including our UKBRC partners, and guide a number of student research projects at MSc and BSc level. We will be recruiting for new NERC research work, and for at least two PhD students in this area early in 2010.

My own research background is in the elucidation of soil organic matter dynamics from modelling measured dynamics of key physical fractions, the topic of my PhD and eight years post-doctoral work at Rothamsted Research, the BBSRC research institute based in Harpenden, Hertfordshire. Biochar should not considered a distinct soil science discipline, and I seek to ensure that knowledge and experience gained from study and simulation of other recalcitrant organic matter fractions - and their interaction with more labile components - is not ignored in seeking understanding of biochar function. By way of example, existing understanding of the contrasting dynamics and interaction of soil fractions was used, in combination with simulation and isotope tracers, to assess the effect of charcoal in terra preta soils on the turnover of other soil carbon. This was my introduction to biochar soil science, and a consequence of collaborative research instigated at Cornell University, NY, where I worked in the group of Johannes Lehmann during 2005. This work is working towards publication.