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Joseph, Stephen
- PublicationQuantifying the Greenhouse Gas Reduction Benefits of Utilising Straw Biochar and Enriched Biochar(Elsevier BV, 2016)
; ; This study investigated the carbon footprint of two different biochar production systems for application to paddy fields. The impacts of using rice straw-derived biochar in raw form (System A) were compared with those arising from using rice straw biochar enriched with lime, clay, ash and manure (System B). The GHG abatement of the management of one Mg of rice straw in Systems A and B was estimated at 0.27 and 0.61 Mg CO₂-eq, respectively, in spring season, and 0.30 and 1.22 Mg CO₂-eq in summer. The difference is mainly due to greater reduction of soil CH₄ emissions by enriched biochar. - PublicationBiochar increases nitrogen retention and lowers greenhouse gas emissions when added to composting poultry litter(Elsevier Ltd, 2017-03)
; ; ; ; ; Biochar has intrinsic and nascent structural and sorption properties that may alter the physical and chemical properties of a composting mixture thus influencing the production of greenhouse gases [GHGs" nitrous oxide (N2O) and methane (CH4)]. In this study, contrasting biochars produced from green-waste (GWB) or poultry litter (PLB) were incorporated into a composting mixture containing poultry litter and straw, and GHG emissions were measured in situ during composting using Fourier Transform Infrared Spectroscopy (FTIR). Emissions of N2O from the biochar-amended composting mixtures decreased significantly (P < 0.05) soon after commencement of the composting process compared with the non-amended control. The cumulative emissions of N2O over 8 weeks in the GWB composting mixture (GWBC), PLB composting mixture (PLBC) and control (no biochar) were 4.2, 5.0 and 14.0 g N2O-N kg−1 of total nitrogen (TN) in composting mixture, respectively (P < 0.05). The CH4 emissions were significantly (P < 0.05) lower in the GWBC and PLBC treatments than the control during the period from day 8 to day 36, when anaerobic conditions likely prevailed. The cumulative CH4 emissions were 12, 18 and 80 mg CH4-C kg−1 of total carbon (TC) for the GWBC, PLBC and control treatments, respectively, though due to wide variation between replicates this difference was not statistically significant. The cumulative N2O and CH4 emissions were similar between the GWBC and PLBC despite differences in properties of the two biochars. X-ray Photoelectron Spectroscopy (XPS) analysis and SEM imaging of the composted biochars indicated the presence of iron oxide compounds and amine-NH3 on the surface and pores of the biochars (PLB > GWB). The change in nitrogen (N) functional groups on the biochar surface after composting is evidence for sorption and/or reaction with N from labile organic N, mineral N, and gaseous N (e.g. N2O). The concentration of NH4+ increased during the thermophilic phase and then decreased during the maturation phase, while NO3− accumulated during the maturation phase. Total N retained was significantly (P < 0.05) higher in the PLBC (740 g) and the GWBC (660 g) relative to the control (530 g). The TC retained was significantly higher in the GWBC (10.0 kg) and the PLBC (8.5 kg) cf. the control (6.0 kg). Total GHG emissions across the composting period were 50, 63 and 183 kg CO2-eq t−1 of initial mass of GWBC, PLBC and control (dry weight basis) respectively. These results support the co-composting of biochar to lower net emissions of GHGs while increasing N retention (and fertiliser N value) in the mature compost.
- PublicationLowering N2O emissions from soils using eucalypt biochar: the importance of redox reactions(Nature Publishing Group, 2015)
; ; ; Van Zwieten, LAgricultural soils are the primary anthropogenic source of atmospheric nitrous oxide (N₂O), contributing to global warming and depletion of stratospheric ozone. Biochar addition has shown potential to lower soil N₂O emission, with the mechanisms remaining unclear. We incubated eucalypt biochar (550°C) - 0, 1 and 5% (w/w) in Ferralsol at 3 water regimes (12, 39 and 54% WFPS) - in a soil column, following gamma irradiation. After N₂O was injected at the base of the soil column, in the 0% biochar control 100% of expected injected N₂O was released into headspace, declining to 67% in the 5% amendment. In a 100% biochar column at 6% WFPS, only 16% of the expected N₂O was observed. X-ray photoelectron spectroscopy identified changes in surface functional groups suggesting interactions between N₂O and the biochar surfaces. We have shown increases in -O-C = N /pyridine pyrrole/NH₃, suggesting reactions between N₂O and the carbon (C) matrix upon exposure to N₂O. With increasing rates of biochar application, higher pH adjusted redox potentials were observed at the lower water contents. Evidence suggests that biochar has taken part in redox reactions reducing N₂O to dinitrogen (N₂), in addition to adsorption of N₂O. - PublicationClimate-change and health effects of using rice husk for biocharcompost: Comparing three pyrolysis systems(Elsevier BV, 2017)
; ; This study presents a comparative analysis of the environmental impacts of different biochar-compost (COMBI) systems in North Vietnam relative to the conventional practice of open burning of rice husks. Three COMBI systems, using different pyrolysis technologies (pyrolytic cook-stove, brick kiln and the BigChar 2200 unit) for conversion of rice husk into biochar were modelled. Biochar was assumed to be composted with manure and straw, and the biochar-compost produced from each system was assumed to be applied to paddy rice fields. Life Cycle Assessment (LCA) showed that the three COMBI systems significantly improved environmental and health impacts of rice husk management in spring and summer compared with open burning, in terms of climate change, particulate matter (PM) and human toxicity (HT) impacts. The differences between the three COMBI systems in the climate change and PM impacts were not significant, possibly due to the large uncertainties. In all systems, the suppression of soil CH4 emissions is the major contributor to the reduced climate effect for the COMBI systems, comprising 56% in spring and 40% in summer. The greatest reduction in the HT impact was offered by the BigChar 2200 system, where biochar is produced in a large-scale plant in which pyrolysis gases are used to generate heat rather than released into the atmosphere. - PublicationBiochar addition in rice farming systems: Economic and energy benefits(Elsevier Ltd, 2017)
; ; ; - PublicationBiochar use for climate-change mitigation in rice cropping systems(Elsevier BV, 2016)
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