This study examined the influence of pyrolysis temperature on biochar characteristics and evaluated its suitability for carbon capture and energy production. Biochar was produced from corn stover using slow pyrolysis at 300, 400 and 500°C and 2 hrs holding time. The experimental biochars were characterized by elemental analysis, BET, FTIR, TGA/DTA, NMR (C-13). Higher heating value (HHV) of feedstock and biochars was measured using bomb calorimeter. Results show that carbon content of corn stover biochar increased from 45.5% to 64.5%, with increasing pyrolysis temperatures. A decrease in H:C and O:C ratios as well as volatile matter, coupled with increase in the concentration of aromatic carbon in the biochar as determined by FTIR and NMR (C-13) demonstrates a higher biochar carbon stability at 500°C. It was estimated that corn stover pyrolysed at 500°C could provide of 10.12 MJ/kg thermal energy. Pyrolysis is therefore a potential technology with its carbon-negative, energy positive and soil amendment benefits thus creating win- win scenario.
Yak dung is used as fuel in Tibetan homes; however, this use is hazardous to health. An alternative use of the dung that would be profitable and offset the loss as a fuel would be very beneficial. Sweet sorghum silage with yak dung biochar as an additive was compared with a control silage with no additives and three silages with different commercial additives, namely Lactobacillus buchneri, Lactobacillus plantarum and Acremonium cellulase. Biochar-treated silage had a significantly greater concentration of water-soluble carbohydrates than the other silages (76 vs 12.4-45.8 g/kg DM) and a greater crude protein content (75.5 vs 61.4 g/kg DM), lactic acid concentration (40.7 vs 27.7 g/kg DM) and gross energy yield (17.8 vs 17.4 MJ/kg) than the control silage. Biochar-treated and control silages did not differ in in vitro digestibility and in total gas (507 vs 511 L/kg DM) and methane production (57.9 vs 57.1 L/kg DM). Biochar inhibited degradation of protein and water-soluble carbohydrates and enhanced lactic acid production, which improved storability of feed. It was concluded that yak dung biochar is an efficient, cost-effective ensiling additive. The profit could offset the loss of dung as fuel and improve the health of Tibetan people.
Previous biochar research has primarily focused on agricultural annual cropping systems with very little attention given to highly fragile, complex and diverse natural alpine grassland ecosystems. The present study investigated the effect of biochar on the growth of alpine meadows and soil health. This study was conducted in the Qinghai Tibetan Plateau over a three year period to investigate the effect of three rice husk biochar application rates alone and combination with high and low NPK fertilizer dosages on alpine meadow productivity, soil microbial diversity as well as pH, carbon and nitrogen content at 0-10 cm and 10-20 cm depth. At the end of the 3rd year soil samples were analysed and assessed by combined analysis of variance. The results showed that biochar application in combination with nitrogen (N), phosphorus (P) and potassium (K) fertilizer had a significant increase in fresh and dry biomass during the second and third year of the study as compared to control and alone biochar application (p ≤ 0.05). Biochar alone and in combination with NPK fertilizer resulted in a significant increase in the soil pH and carbon contents of the soil. XPS results, the SEM imaging and EDS analysis of aged biochar demonstrated that the biochar has undergone complex changes over the 3 years as compared to fresh biochar. This research suggests that biochar has positive effect on alpine meadow growth and soil health and may be an effective tool for alpine meadow restoration.