developed a sub-model to integrate biochar into the Environmental Policy Integrated Climate (EPIC) model by allowing for the effect of biochar on the initial soil properties represented in the model, but not explicitly for biochar turnover 20. developed a biochar sub-model for the Agricultural Production System Simulator (APSIM), and its simulations compared favourably with some experimental observations, but it lacked wider calibration and validation 19. However, this pool has a turnover time of 10 to 50 year 17 which is at least an order of magnitude faster than typical biochar turnover 18. Dil and Oelbermann adapted the CENTURY model to evaluate the long-term effect of biochar by representing it as 95% lignin added to the ‘slow C pool’ in CENTURY 16. (2016) found a wide range of priming effects depending on biochar and soil characteristics but they found consistently large priming effects in low-fertility sandy soils which are typical of many sugarcane areas.Īttempts to model long-term increases in SOC following biochar application have relied on data from short-term studies 15. Studies report negative, positive and no priming effect 12, 13, 14, sometimes with a change in the direction of priming over time, typically from increased SOC mineralisation in the first year or so, to decreased mineralization thereafter 12. The effects on existing soil organic carbon (SOC) may lead to increased SOC mineralization (‘positive priming’) or decreased mineralization (‘negative priming’) 12, 13. The properties of biochar vary according to pyrolysis conditions and other manufacturing parameters as well as the nature of the biomass ‘feedstock’ 10, 11. Predicting the potential of biochar for these purposes requires allowance for the wide range of biochar types that can be created, and the variable effects of soil conditions on biochar decomposition, and vice versa. It is also argued that biochar has additional GHG abatement potential through effects on crop production, including reduced requirement for manufactured fertilizer 7. Another option is to make biochar, which potentially provides greenhouse gas (GHG) removal as well as returning carbon (C) and nutrients to the soil 8, 9. A potential alternative use of the trash is for energy generation, substituting for fossil fuels 6, 7. Currently it is typical for all the trash to be left on the field, although studies into sustainable rates of removal have been made 4, 5. Although trash provides a mulch that can benefit soil fertility and the growth of subsequent crops, it can also increase the risk of fire, pest proliferation, and reduced soil warming and drying in the spring 2, 4. This ‘green harvesting’ leaves large quantities of biomass (hereafter referred as ‘trash’) in the field 3. However, to avoid air pollution, in many countries the fields are now mostly left unburned and harvested mechanically. Sugarcane fields were traditionally burned to facilitate manual harvest 2. Sugarcane ( Saccharum officinarum L.) is the world's largest crop by production quantity, with a total of 1.8 billion tonnes of cane produced globally per annum in more than 90 countries 1. Future research should (a) further validate the model with field experiments (b) make a full life cycle assessment of the potential for greenhouse gas mitigation, including additional effects of biochar applications on greenhouse gas balances. Scaling to the total sugarcane area of the State, this would be 50 Mt of CO 2 equivalent year −1, which is 31% of the CO 2 equivalent emissions attributed to the State in 2016. The results show a potential increase in soil C stocks by 2.35 ± 0.4 t C ha −1 year −1 in sugarcane fields across the State at application rates of 4.2 t biochar ha −1 year −1. Third, we used the model to explore the potential for soil C sequestration with sugarcane biochar in São Paulo State, Brazil. Second, we evaluated the modified model against published field data, and found satisfactory agreement between observed and predicted soil C accumulation. First, we modified the RothC model to allow changes in soil C arising from additions of sugarcane-derived biochar. We investigated the potential for sequestering carbon (C) in soil with these residues by partially converting them into biochar (recalcitrant carbon-rich material). Sugarcane ( Saccharum officinarum L.) cultivation leaves behind around 20 t ha −1 of biomass residue after harvest and processing.
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