Properties of long-term biochar amended soils: Greenhouse gas emissions and microbial community diversity

Background and Aims Biochar application is important in mitigating greenhouse gas (GHG) emissions. Several studies have shown that adding to soil biochar can reduce emissions of methane, nitrous oxide and carbon dioxide. Additionally, biochar application stimulates soil microbial activity. Previous studies have also shown that biochar can alter microbial communities’ structure, with positive effects on carbon and nitrogen cycles. However, there is little published data on long-term behavior of biochar in soil. Therefore, the present study aims to assess the effect of long-term application of biochar on GHGs emissions. Methods Untreated soil, soil with a single application of biochar in 2009 and soil with two applications of biochar in May 2009 and February 2010 were used to set up mesocosms in jars each filled with 0.6 Kg of dry soil not supplemented, or supplemented with digestate or urea. The production of GHGs was measured 8 times in 23 days using a portable DX4040 Fourier Transformed Infrared (IR) Spectroscopy (FTIR)-Gas Analyzer (Gasmet Technology Oy, Helsinki, Finland). A soil sample was taken at each measurement to assess microbial activity. RNA extraction from 0.5 g of soil was carried out using the RNeasy Power Total RNA Kit (QIAGEN GmbH, Hilden, GERMANY) following the manufacturer’s instructions. To assess the bacterial activity RT-qPCR was conducted. Results The data analyses are ongoing. Conclusions At the end of the processing, it will be possible to evaluate: i) biochar retains its GHGs mitigation properties; ii) the reduction is the same for both fertilizer types; iii) the diversity of bacteria active in the emission process.