How does biochar affect soil respiration?

Agricultural soils are an important landscape element in terms of climate change and this ecosystem is considered as a one of the major source of greenhouse gases (GHGs). Soil may be also a sink for GHGs, from this reason so many research projects are focused on determination of factors and conditions affecting gas exchange. Biochar is produced from biomass that has been pyrolysed in a zero or low oxygen availability. It is currently widely considered as a stable addition to the soil, which not only improve its fertility, but also can mitigate climate change. Considering landscape elements, the char also prevents carbon loss from forest soils. Higher microbial activity is usually associated with higher carbon dioxide (CO₂) production (soil respiration). One of the most important questions is how does biochar influence production of GHGs such as CO₂? Which doses have a critical meaning for CO₂ emission? The aim of our study was to determine the effect of wide range doses of biochar (produced from sunflower husks) (from 1 to 100 Mg ha^-1) to Haplic Luvisol soil from fallow fields. We investigated the changes of CO₂ emission during laboratory incubation using gas chromatography method. In short-term incubations soil respiration was positively correlated with increasing biochar dose, while during long-term (several years) observation, the impact of biochar dose on the amount of emitted CO₂ was not so significant. It is worthwhile to conduct short- term and long-term field studies in this area.

Research was partially conducted under the project “Water in soil - satellite monitoring and improving the retention using biochar” no. BIOSTRATEG3/345940/7/NCBR/2017 which was financed by Polish National Centre for Research and Development in the framework of “Environment, agriculture and forestry” - BIOSTRATEG strategic R&D programme.