High concentration (50%) biochar does not negatively effect early germination or root growth
Biochar generated as a by-product of combined heat and power gasification is classified as waste, for which the UK does not currently have a safety protocol for use in the open environment. The UEA is working with the Environment Agency to determine environmental tolerance limits, in order to assess potential environmental risks (ex: PAH contamination). My preliminary study aimed to measure any negative plant growth effects by amended soil with high concentrations of biochar under controlled laboratory conditions.
We characterised physical and chemical properties from woodchip biochar obtained from the UEA gasifier (800°C for 30 minutes). The organic structure appeared to be retained. Heavy metals were present in very low concentrations (>350 ppm). Relatively high concentrations of Ca+ and K+ were present. Lettuce (Lactuca sativa) were germinated and put in pots containing 0, 3, 10, and 50% of biochar mixed with compost in a short-day growth chamber at a constant 22°C. The preliminary results show no difference in root and shoot growth between the biochar and control treatments. High concentrations (50%) do not appear to inhibit or enhance root-shoot growth compared to the control. A further experiment will be carried out to determine the long term (180 day) root-shoot growth of plants under several biochar (0, 3, 10, 50%) and fertiliser fertilisation (0, 50, 75, 100kg N/ha) rates.