Mechanisms and socio-economics of carbon sequestration and soil quality improvement of biochar in weathered, acidic agricultural lands

Soil additions of biochar, in particular from cacao shell, improves soil quality as it reduces plant-available, toxic aluminium, a major cause of crop failure in the tropics (Martinsen et al., J. Plant Nutr. and Soil Science, submitted). This positive effect of biochar was confirmed by pot trials using maize and rice in acid, sandy soils of Malaysia. Field tests focusing on sandy soils are underway and will be reported shortly. In Indonesia, field tests in acidic Ultisols (Lampung, Sumatra) were done on three crops (lowland rice, upland rice, maize), two types of biochar (cacao shell and rice husk), and two types of agricultural practice (conventional and conservation farming). The first three cropping seasons (biochar added in the first year only) show doubling of yields, especially for maize. Cacao shell biochar has the strongest effect, as hypothesized. The trials will be continued for at least one more season to investigate long-term effects (part of an externally funded Indonesian PhD at ISRI, Bogor). Laboratory studies show that biochars from both cacao shell and corn cob have modest effects on sorption of nutrients (Hale et al., 2013. Chemosphere and Alling et al., 2014, J. Plant Nutr. and Soil Science). By contrast, we find strong, stable binding of organic pollutants, like pyrene, to biochar (Hale et al., 2011, Environ. Sci. Technol). Biochar in soils reduces the emission of N2O, an intermediate denitrification product and a potent greenhouse gas, with cacao shell biochar being more effective than rice husk biochar. Decreased emission of N2O is mainly due to better assembly at higher pH of the N2OR enzyme that converts N2O to N2 (Obia et al., Soil Biology and Biochemistry, submitted). Field tests for confirmation are underway at Lampung, Indonesia (Jubaedah, PhD student Indonesia and post doc Jing Zhu, NMBU). Although biochar is resistant to decomposition, there may significant losses from soils due to leaching. This is currently investigated for rice husk biochar in maize fields, using stable isotopes (to be reported soon in Alfred Obia?s PhD thesis at NMBU). Biochar production may cause significant air pollution. Our partner at the University of Kuala Lumpur designed and implemented an upscale version of the Belonio stove for clean and controlled biochar generation. Scientifically novel measurements have been done to estimate gas emissions from this improved biochar generation unit (Cornelissen et al., In preparation). Inventory data from rice mills, including direct measurements and interviews of management and technical staff in Malaysia, were the basis of a Life Cycle Assessment (LCA) and Life Cycle Cost analysis (LCC). We also investigated the life cycle impact of biochar implementation in Ngata Toro, a rural village in Central Sulawesi. In one of our case studies from a parallel project in Zambia, where we have a complete data set, the environmental and socio economic benefits of different biochar production and utilization systems was investigated, through a combined LCA and cost benefit analysis (CBA) (Sparrevik et al., 2013. Environ. Sci. Technol.). In collaboration with UNDP (Jakarta), we conducted CBA and business concepts around energy derived from biochar generation. Economic data were collected for different types of kilns and gasifiers suitable for producing biochar (Sulawesi, Indonesia). In addition, production of biochar for cooking purposes has been investigated as alternative to soil amendment. Preliminary results indicate that agricultural purposes are a better alternative than biochar briquettes. The most important aspect with respect to energy generation has been to utilize the heat to sustain a high yield of biochar by using environmentally friendly retort kilns. A large follow-up project is initiated by UNDP, Jakarta, with our consortium as a partner.

Biochar is charcoal from pyrolysis of organic waste. When mixed into soil, biochar is stable, and thus its carbon is removed from the carbon cycle. This mitigates climate change. Due to its alkaline reaction, biochar also increases soil quality by reducin g soil acidity. Particularly, in Asia, with its extensive areas of acidic soils, this is very relevant, as soil acidity reduces crop yields. We aim at investigating the potential of biochar from organic waste to sequester carbon and improve soil quality a nd thus livelihoods. The research program involves social and agricultural/environmental components. Social-scientific components include biochar generation concepts and a life cycle assessment comparing use of biochar to conventional energy production an d fertilizer use, specific for tropical conditions. Life cycle cost assessment will address investments, income, and revenues. The agricultural/environmental part consists of initial chemical screening of soil-biochar combinations, followed by extensive p ot and field trials as well as mechanistic lab studies. Social, environmental and agricultural scientists from universities and research institutes in Norway, Indonesia and Malaysia will collaborate. UNDP Indonesia will lead knowledge transfer, dissemina ting project findings to local institutes, extension services and farmers. Three PhDs are envisioned in Norway + Indonesia. Mutual research visits and workshops will ascertain knowledge transfer. The proposed research addresses the call, as it integrates environmental and development science, with its focus on the potential of biochar to increase carbon sequestration, while at the same time contributing to sustainable land use. The project is multidisciplinary and integrates social, agricultural, and envi ronmental sciences. The Indonesian Embassy in Norway supports the proposal (support letter attached).