Opportunities and constraints for biochar technology in Australian agriculture: looking beyond carbon sequestration

Singh, Balwant; Macdonald, Lynne M.; Kookana, Rai S.; Zwieten, Lukas Van; Butler, Greg; Joseph, Stephen; Weatherley, Anthony; Kaudal, Bhawana Bhatta; Regan, Andrew Thomas; Cattle, Julie; Dijkstra, Feike A.; Boersma, M.; Kimber, Stephen; Keith, Alexander; Esfandbod, Mohsen

doi:10.1071/sr14112

Cited by 55 publications

(26 citation statements)

References 76 publications

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“…Recently, biochar soil application has been discussed at the United Nations Framework Convention on Climate Change for possible consideration as a potential climate mitigation technology in accounting carbon credit (International Biochar Initiative), and a methodology for including biochar soil application as a carbon trading option has been reviewed by the American Carbon Registry (Koper et al 2013). However, significantly more studies are needed before this approach can be considered for wide-spread commercial implementation (Novak et al 2014;Baronti et al 2014;Dai et al 2013;Singh et al 2015Singh et al , 2014Zhang et al 2010;Blackwell et al 2010;Spokas et al 2010;Beesley et al 2010;Topoliantz et al 2005). In this paper, we report the results of a biochar characterization study performed at ORNL using biochar materials produced from peanut hulls and pine wood under various different pyrolysis conditions as part of the efforts to develop better biochar materials for potential application as a soil amendment and carbon sequestration agent.…”

Section: Introductionmentioning

confidence: 99%

Characterization of biochars produced from peanut hulls and pine wood with different pyrolysis conditions

Lee

Hawkins²,

Kidder

et al. 2016

Bioresour. Bioprocess.

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Background: Application of modern biomass pyrolysis methods for production of biofuels and biochar is potentially a significant approach to enable global carbon capture and sequestration. To realize this potential, it is essential to develop methods that produce biochar with the characteristics needed for effective soil amendment.Methods: Biochar materials were produced from peanut hulls and pine wood with different pyrolysis conditions, then characterized by cation exchange (CEC) capacity assays, nitrogen adsorption-desorption isotherm measurements, micro/nanostructural imaging, infrared spectra and elemental analyses.Results: Under a standard assay condition of pH 8.5, the CEC values of the peanut hull-derived biochar materials, ranging from 6.22 to 66.56 cmol kg −1 , are significantly higher than those of the southern yellow pine-derived biochar, which are near zero or negative. The biochar produced from peanut hulls with a steam activation process yielded the highest CEC value of 66.56 cmol kg −1 , which is about 5 times higher than the cation exchange capacity (12.51 cmol kg −1 ) of a reference soil sample. Notably, biochar produced from peanut hulls with batch barrel retort pyrolysis also has a much higher CEC value (60.12 cmol kg ) from Eprida's H 2 -producing continuous steam injection process. The CEC values were shown to correlate well with the ratios of oxygen atoms to carbon atoms (O:C ratios) in the biochar materials. The higher O:C ratio in a biochar material may indicate the presence of more hydroxyl, carboxylate, and carbonyl groups that contribute to a higher CEC value for the biochar product. In addition, the increase in surface area can also play a role in increasing the CEC value of biochar, as in the case of the steam activation char. Conclusion:Comparison of characterization results indicated that CEC value is determined not only by the type of the source biomass materials but also by the pyrolysis conditions. Biochar with the desirable characteristics of extremely high surface area (700 m 2 /g) and cation exchange capacity (> 60 cmol kg) was created through steam activation.

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Section: Introductionmentioning

confidence: 99%

Characterization of biochars produced from peanut hulls and pine wood with different pyrolysis conditions

Lee

Hawkins²,

Kidder

et al. 2016

Bioresour. Bioprocess.

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“…Numerous management technologies have been proposed to mitigate N losses from agricultural systems, including the proper management of soil C because of its effects on soil properties and processes, including N cycling (Dil, Oelbermann, & Xue, 2014; Ding et al., 2010). Carbon management practices that include amendments with high C content, such as biochar, can boost soil fertility and quality by raising pH and by improving water holding capacity, cation exchange capacity (CEC), and nutrient retention (Bridgwater, 2003; Filiberto & Gaunt, 2013; Singh et al., 2014).…”

Section: Introductionmentioning

confidence: 99%

Optimum rates of surface‐applied coal char decreased soil ammonia volatilization loss

et al. 2020

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Fertilizer N losses from agricultural systems have economic and environmental implications. Soil amendment with high C materials, such as coal char, may mitigate N losses. Char, a coal combustion residue, obtained from a sugar factory in Scottsbluff, NE, contained 29% C by weight. A 30‐d laboratory study was conducted to evaluate the effects of char addition on N losses via nitrous oxide (N2O) emission, ammonia (NH3) volatilization, and nitrate (NO3–N) leaching from fertilized loam and sandy loam soils. Char was applied at five different rates (0, 6.7, 10.1, 13.4, and 26.8 Mg C ha−1; char measured in C equivalent) to soils fertilized with urea ammonium nitrate (UAN) at 200 kg N ha−1. In addition, there were two negative‐UAN control treatments: no char (no UAN) and char at 26.8 Mg C ha−1 (no UAN). Treatment applied at 6.7 and 10.1 Mg C ha−1 in fertilized sandy loam reduced NH3 volatilization by 26–37% and at 6.7, 10.1, and 13.4 Mg C ha−1 in fertilized loam soils by 24% compared with no char application. Nitrous oxide emissions and NO3–N leaching losses were greater in fertilized compared with unfertilized soil, but there was no effect of char amendment on these losses. Because NO3–N leaching loss was greater in sandy loam than in loam, soil residual N was twofold higher in loam than in sandy loam. This study suggests that adding coal char at optimal rates may reduce agricultural reactive N to the atmosphere by decreasing NH3 volatilization from fertilized soils.

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“…In addition to providing high nutrient and water retention, replacing peat with BC could offset or reverse the C footprint of soil-free substrates into a net C sink (Woolf et al, 2010). Evidence to-date suggests neutral or positive effects of BC use in substrates on nutrient availability and plant growth (as reviewed by Singh et al, 2014), though many studies examine additions of BC to peat-based substrates, rather than replacing a substrate component such as peat (i.e., substitution).…”

Section: Introductionmentioning

confidence: 99%

Substitution of peat moss with softwood biochar for soil-free marigold growth

Margenot

Griffin

Alves

et al. 2018

Industrial Crops and Products

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A B S T R A C TPeat moss has historically been a key component of soil-free substrates in the greenhouse and nursery industries. However, the increasing expense of peat, negative impacts of peat mining on wetland ecosystems, and growing perception of peat as unsustainable have led to investigation for alternatives. Biochar (BC) is a promising substitute for peat, yet the majority of studies examine additions of BC to peat-based substrates rather than replacing the peat component or employ relatively low substitution rates. Furthermore, at high substitution rates the alkalinity common to many BCs may increase substrate pH and adversely impact plant production. We evaluated BC substitution for peat and pH adjustment of resulting substrates on marigold (Tagetes erecta L.) performance under standard greenhouse conditions. A high pH (10.9) softwood BC (800°C) was substituted for peat in a standard 70:30 (v/v) peat:perlite mixture at 10% total volume increments. Substrate pH was either not adjusted or adjusted to pH 5.8 using a BC by-product, pyroligneous acid (PLA). Germination was inhibited in pH adjusted substrates with high BC substitution (50-70% total substrate volume) likely due to higher dosages of PLA needed to neutralize pH. At harvest (flowering stage, 9 weeks) the initial pH gradient (4.4-10.4) in substrates that were not pH adjusted had converged to pH 5.6-7.5, and BC substitution for peat did not negatively impact marigold biomass or flowering. At low substitution rates (10-30% total substrate volume), marigold biomass and leaf SPAD values were greater than the control peat-perlite mixture (0% BC). This study demonstrates that softwood BC can be considered as a full replacement for peat in soil-free substrates, and even at high rates (70% total substrate volume) does not require pH adjustment for marigold production. Crop-and BC-specific considerations and economic potential should be investigated for wider application.

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Opportunities and constraints for biochar technology in Australian agriculture: looking beyond carbon sequestration

Cited by 55 publications

References 76 publications

Characterization of biochars produced from peanut hulls and pine wood with different pyrolysis conditions

Characterization of biochars produced from peanut hulls and pine wood with different pyrolysis conditions

Optimum rates of surface‐applied coal char decreased soil ammonia volatilization loss

Substitution of peat moss with softwood biochar for soil-free marigold growth

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