Modelling the potential for soil carbon sequestration using biochar from sugarcane residues in Brazil

Abstract

Sugarcane (Saccharum officinarum L.) cultivation leaves behind around 20 t ha−1 of biomass residue after harvest and processing. We investigated the potential for sequestering carbon (C) in soil with these residues by partially converting them into biochar (recalcitrant carbon-rich material). First, we modified the RothC model to allow changes in soil C arising from additions of sugarcane-derived biochar. Second, we evaluated the modified model against published field data, and found satisfactory agreement between observed and predicted soil C accumulation. Third, we used the model to explore the potential for soil C sequestration with sugarcane biochar in São Paulo State, Brazil. 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. Scaling to the total sugarcane area of the State, this would be 50 Mt of CO2 equivalent year−1, which is 31% of the CO2 equivalent emissions attributed to the State in 2016. 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.

Assessing the carbon capture potential of a reforestation project

“…We then computed a sigmoid curve between the forest litter input needed for the degraded soil C stock (minimum litter input) and the maximum forest litter input needed to reach the adjacent forest soil C stock (maximum litter input) to describe the required carbon input over time, reaching maximum carbon input 40 years after transplanting 32 , 33 and used this increasing carbon input over time in RothC to compute the soil carbon change following seedling transplant (as described in Cerri et al 34 ). We accounted for biochar soil carbon stock impacts following the approach described in Lefebvre et al 35 and used their modified coding of RothC in R. Meteorological data, soil and additional data required for RothC are given in the “ Supplementary Information ” file.…”

Brazil’s sugarcane embitters the EU-Mercosur trade talks

“…Consequently, this strategy could represent an opportunity for the Brazilian sugarcane industry to meet the rising demand for ethanol and sugar while achieving the country’s sectoral mitigation objectives (i.e., the NDC and Low Carbon Agriculture 39 targets) along with the compliance with national and international environmental standards (i.e., REDII and RenovaBio environmental criteria). To this end, taking a long-term perspective, the amendment of more sustainable supplies, such as biochar, could further increase soil proprieties and agricultural productivity of degraded pasturelands, while contributing to lower emissions 40 , 41 . The potential conversion of the Amazon and Cerrado native vegetation to sugarcane could be marginal, resulting in limited LULUCF emissions.…”

Inclusion of biochar in a C-dynamics model based on observations from a 8 years field experiment

“…In a study on biochar modelling, Lefebvre et al (2020a) (Stockmann et al 2013;Abbruzzini et al 2017). Using the results for the long term degradation of biochar we can elaborate further on this problem; as it was done by Jiang et al (2019).…”

“…By contrast, in the present study the BC-RothC model was modified and parametrized based on the results of a three year experiment (Ventura et al 2019a) and validated in the long term (eight years). Furthermore, Lefebvre et al (2020a) evaluated their model with literature data from continuous addition of rice straw biochar to wheat maize cultivation (Liu et al 2020), but not calibrated nor validated for the specific experimental conditions.…”