Long-Term Effects of Biochar on Vineyard Soil: a mesocosm experiment

Applying biochar is important in mitigating greenhouse gas (GHG) emissions. Several studies have shown that adding biochar to soil can reduce methane, nitrous oxide, and carbon dioxide emissions. Additionally, its application stimulates soil microbial activity. Previous studies have also shown that biochar can alter the structure of microbial communities. However, there is little published data on the long-term behavior of biochar in soil. This study aims to assess the effect of long-term application of biochar on GHG emissions. Untreated vineyard soil, vineyard soil with a single application of biochar at a rate of 22 t ha-1 in May 2009, and vineyard soil with two applications of biochar at 22 t ha- 1 each in May 2009 and February 2010 were used to set up mesocosms in 1000 cm3 polyethylene jars, each filled with 0.25 kg of dry soil. Mesocosms were unsupplemented or supplemented with digestate or urea. The GHGs production was measured 10 times in 21 days using a portable DX4040 (FTIR) Gas Analyzer (Gasmet Technology Oy, Helsinki, Finland). A soil sample was taken at the beginning and end of incubation to evaluate the composition and diversity of microbial communities. DNA was extracted from 0.5 g of soil. To assess bacterial activity, RT-qPCR was conducted. Data analyses showed that soil with a double dose of biochar showed lower cumulative CO2 and N2O emissions rates and significant differences in the microbial community. Biochar amended on soil longterm retains its GHG mitigation properties and modulates microbial community.