Special Issue "Biochar as Option for Sustainable Resource Management"

Guest Editor
Prof. Dr. Bruno Glaser
Soil Biogeochemistry, Martin-Luther-University, Halle-Wittenberg, Von-Seckendorff-Platz 3, 06120 Halle/Saale, Germany
Website: http://www.landw.uni-halle.de/prof/bodenbiogeochemie/mitarbeiterinnen/bruno_glaser/
E-Mail: bruno.glaser@landw.uni-halle.de
Phone: +49 345 5522531

Dear Colleagues,

Recently, biochar has been proposed as means of sequestering C as a stable form in soil. Suitability of biochar for C sequestration depends on the overall C balance of biochar after carbonization and its long-term stability in soils. Other observed yet poorly understood benefits of biochar application include decreases in greenhouse gas (GHG) emissions, increase of nutrient and water retention, stabilization and destabilization of native soil organic matter, and decrease of bioavailability of organic/inorganic contaminants in soils. Biochar-induced immobilization of toxic metals in contaminated soils has recently received considerable attention. Despite these diverse benefits of biochar on a variety of soil properties, fundamental knowledge in soil-plant-water-biochar interactions is still lacking. Long-term ecological sustainability should be taken into account when applying biochar to soil for agriculture or remediation.

Prof. Dr. Bruno Glaser
Guest Editor

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Agronomy is an international peer-reviewed Open Access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. For the first couple of issues the Article Processing Charge (APC) will be waived for well-prepared manuscripts. English correction and/or formatting fees of 250 CHF (Swiss Francs) will be charged in certain cases for those articles accepted for publication that require extensive additional formatting and/or English corrections.

• biochar standardization/certification
• land use impact
• life cycle assessment
• integration of scientific results
• results of experimental studies

Type of Paper: Article
Title: Influence of Biochar Feedstock on the Transport of Pathogenic Bacteria in Unsaturated Biochar-Amended Soil
Author: Carl Bolster
Affiliation: USDA-ARS, 230 Bennett Ln., Bowling Green, KY 42104, USA
Abstract: Recent studies have shown that biochar amendment influences bacterial transport in soils. In this study, we investigated the effect of biochar feedstock on the transport of pathogenic bacteria through fine sand under partially-saturated conditions. Biochars produced from four feed stocks including pine chips, sun hemp, dairy manure and swine manure that were pyrolyzed at 700 °C were separately added to fine sand (2% w/w) and packed in cylindrical columns. Known concentrations of Escherichia coli O157:H7, Salmonella typhimurium, Enterococcus faecalis and Listeria monocytogenes were applied to separate partially-saturated columns and leached with bacteria-free solution. Bacteria that were transported through the columns were quantified.  All four biochars significantly increased the retention of all bacteria with up to 100% of applied bacteria retained in the porous media. The increase in total organic matter and specific surface brought about by the addition of the biochars seems to be responsible for the increased retention. The effectiveness of the added biochars varied between bacteria with relatively more pronounced effect on the retention of E. faecalis and L. monocytogenes which could be attributed to differences in surface properties among bacteria. These results show the potential of utilizing biochars as soil amendment to limit the transport of pathogenic bacteria.

Type of Paper: Review
Title: Impact of Biochar on Contaminants in Soil: A Tool for Mitigating Risk?
Authors: Ogbonnaya U. Ogbonnaya and Kirk T. Semple *
Affiliation: Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK
Abstract: The presence of biochar in soils through natural processes and soil application has received significant amount of scientific and regulatory attention. Biochar alters soil properties, encourages microbial activity and enhances sorption of inorganic and organic compounds, but strongly depends on the feedstock and production process of biochar. This paper considers biochar potential sources, production processes, interactions with soil and associated biota. Furthermore, interactions between biochar and polycyclic aromatic hydrocarbons (PAHs) are considered with focus on factors governing sorption and bioaccessibility in biochar-amended soils. In conclusion this paper considers the feasibility of applying biochar in remediation technologies.
Type of manuscript: Article

Type of Paper: Article
Title: Impact of Biochar on Arsenic Uptake in Tomato Plants (Solanum lycopersicum L.)
Authors: Luke Beesley ¹, Marta Marmiroli ², Luca Pagano ², Veronica Pigoni ², Nelson Marmiroli ²
Affiliations: ¹ The James Hutton Institute, Craigiebuckler, Aberdeen, AB158QH, UK; ² Department of Life Sciences, University of Parma, 43100 Parma, Italy.
Abstract: Orchard prune residue biochar (500 °C) was mixed with a heavily As contaminated mine soil (~6000 mg kg−1) and germinated tomato plants (Solanum lycopersicum L.) were transplanted to the mixtures as well as controls without biochar amendment. In the following 4 weeks, under greenhouse conditions, soil pore water was sampled to evaluate As mobility in response to the biochar and the maturing plant growth; thereafter, upon flowering and fruiting, plants were destructively sampled to determine element uptake. Biochar increased As concentrations in pore water between 2 and 3 times (> 500 µg L−1 to < 2000 µg L−1) whilst both root and shoot concentrations were reduced (3 and 5 fold respectively). Biomass changes between amended and control soil were insignificant so as to suggest that biochar did not act as a fertiliser. The results indicate that high concentrations of soluble As may be rapidly leached away, rather than taken up by plants after biochar addition.

Type of Paper: Article
Title: Quantifying the Climate Change Mitigation Benefits of Utilising a Mobile Biochar Reactor as an Alternative to In Field Burning
Authors: Stephen Joseph ^1,2, Annette Cowie ³ and Genxing Pan ²
Affiliations: ¹ School of Materials Science and Engineering, University of New South Wales, NSW 2052, Australia; ² Center for Biochar and Green Agriculture, Nanjing Agricultural University, Nanjing 210095, China; ³ National Centre for Rural Greenhouse Gas Research, University of New England, Armidale 2351, Australia
Abstract: To determine if a specific biochar technology is a “carbon negative”  it is necessary to document the whole life cycle GHG balance of biochar production and utilization, and compare this with conventional practice. The assessment should include:

• fossil fuel emissions from transport , processing and plant construction,
• net emissions of nitrous oxide and methane,
• direct and indirect carbon stock change associated with feedstock supply
• impact on crop yield and requirements for fertilizer and herbicide
• fossil fuel emissions displaced through use of syngas as an energy source, where relevant.

The appropriate methodology for assessment of mitigation benefits of biochar is illustrated through a study of GHG balance (biochar case) in comparison with current practices (reference case). The emissions reduction benefit of biochar systems is calculated as the difference in net emissions between the biochar and reference cases. In-field burning of residues either from crops or from land clearing is a major source of greenhouse gas emissions.  This paper explores the impact on net greenhouse gas emissions from utilization of a mobile biochar reactor developed by Anthroterra Pty.  It shows that processing plant residues that are otherwise burned into biochar can   increase recalcitrant soil carbon  and significantly decrease greenhouse gas emissions.

Type of Paper: Article
Title: Lifecycle Assessment of Three Real and Functioning Commercial Pyrolysis Biochar Systems in Europe
Authors: Jim Hammond ^1,*, Jan-Markus Roedger ², Simon Shackley ¹ and Achim Loewen ²
Affiliations: ¹ UK Biochar Research Centre, School of Geosciences, University of Edinburgh, Kings Buildings, Edinburgh, EH9 3JN, UK; ² Faculty of Resource Management, University of Applied Sciences and Arts, Hildesheim/Holzminden/Göttingen, Gottingen, Germany
Abstract: Biochar has been raised as a versatile tool to simultaneously address global warming, improve agricultural soils, create bio-energy and dispose of organic wastes. Assessments of greenhouse gas benefits, energy balance and the economics of such systems have largely been extrapolated from multiple partial datasets with gaps filled by assumptions based on laboratory research or agricultural evidence from other climatic regions. This paper presents greenhouse gas, energy and economic assessment of three complete datasets based on three operational commercial biochar production facilities and the use of their biochar in agricultural soils according to the ISO 14040/44. The systems studied are at a relatively early stage according to the technology readiness level, and as such generally perform less well than the earlier, more speculative assessments of biochar systems predicted. This is not an indictment of the technology but a necessary phase in the process of developing functioning technology from ambitious concepts. The generation of useful energy either in the form of heat or power differ between systems studied, but all cases assessed prove to be carbon negative, and, most importantly for commercial systems, economically viable.

Type of Paper: Article
Title: Process Water of HTC: Phytotoxic or a Fertilizer?
Authors: A. Kruse, W. Buss, T. Ullrich, F. Reebs and D. Wüst
Affiliations: Institute of Catalysis Research and Technology, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
Abstract: Process water of HTC includes organic compounds, which may influence seeding, or growth of plants. On the other hand, it includes Potassium salts and Phosphates, which may be fertilizers. Several substances found in the process water showed phototoxic effects on cress development in concentrations as in HTC process water: glycolic acid, levulinic acid and guaiacol inhibited germination; acetic acid, glycolaldehyde dimer and catechol reduced seedling growth. Different concentrations of process water in soil were tested in leaching tests regarding their groundwater contamination potential. All these compounds are degraded in soil, which was also shown with cress tests. In addition, the value of the process water as fertilizer was tested with plants and discussed in view of German regulations. The formation of the organic compounds and fertilizer compounds was also investigated.

Type of Paper: Article
Title: Nutrient Availability, Metal Solubility and Leachability, and Liming Potential of Biochar Produced From Different Feedstock and Processes
Authors: Amir Hass, Javier M. Gonzalez, Isabel M. Lima, Akwasi A. Boateng, Dharmesh Patel, Joan F. Lamb, William F. Anderson, and Nathan O. Nelson
Affiliations: Agricultural and Environmental Research Station, Gus R. Douglass Land-Grant Institute, West Virginia State University, Institute, WV 25112, USA
Abstract: Biochar, the byproduct of the pyrolysis of biomass to energy and oil alternative products is considered a beneficial soil amendment. We evaluate several environmental and agronomic-related properties of biochar produced from different feedstocks, different pyrolysis conditions and with/out steam activation. Chicken litter feedstock was processed at 350 ºC or 700 ºC in a slow pyrolysis; additionally, chicken litter, alfalfa stem, bamboo, miscanthus giganteus, and sorghum stover feedstocks were processed in fast pyrolysis at 450-500 ºC. Subsamples of all biochars were further steam-activated at 800 ºC. Biochar liming potential, total, water, AB-DTPA (ammonium bicarbonate diethylene triamine pentaacetic acid), Mehlich-3, and SPLP (synthetic precipitation leaching procedure; EPA Method 1312) extractable metals were determined. Biochar liming potential (CCE) was feedstock dependent, decreasing in the order: chicken litter >> alfalfa > bamboo > sorghum > miscanthus. Higher process temperature was associated with high CCE. Metal enrichment factor by pyrolysis (i.e. metal concentration in biochar/metal concentration in feedstock) was 2.5±0.7. Metal enrichment by steam-activation of biochars was temperature dependent, increasing metals in biochar produced at 350 ºC (from 1.3 to 1.7) whereas smaller changes were observed in biochar produced at 700 ºC (from 0.9 to 1.0). Though metals concentration in water was feedstock dependent, their solubility decreased in the order alkali metals > alkaline earth metals > transition metals. While alkaline earth and transition metals solubility in SPLP and Mehlich-3 decreased upon pyrolysis and biochar activation, potassium solubility increased. Depending on feedstock pyrolysis processing and activation, biochar may contribute soluble, and bio-available metals. Understanding the impact of feedstock, pyrolysis conditions, and activation on biochar properties could improve our understanding of its beneficial use in agriculture.

Title: Biochar-Slurry Applications to a Temperate Grassland Soil: Lessons Learned from Field and Lab
Author: Sonja Schimmelpfennig
Affiliation: Soil Physics Section, Univ. of Bayreuth, Universitätsstr. 30, 95440 Bayreuth, Germany
Abstract: We present first results from a biochar-grassland field study, combined with results from an appending incubation experiment. The focus of the field study is to assess the stability of charred material under grassland conditions with the focus on possible risks due to unknown interactions with the ecosystem, e.g. increased greenhouse gas- or ammonia emissions. Biochar top dressing was combined with repeated slurry amendments to simulate real grassland conditions. Since top dressing of the substrates did not interact with the soil in the first year, we complemented the field study by an incubation experiment with similar preconditions, but where the biochar substrates were intermixed with the soil. Next to pyrolytic biochar, we applied untreated feedstock (Miscanthus x giganteus) and vapothermally treated miscanthus under the same conditions to obtain a range of comparable labile or recalcitrant organic materials in soil. Our results show differing behavior of our organic amendments if either top dressed or mixed with soil. If mixed with soil, there is no risk of biochar in increasing CO₂ and N₂O emissions, and methane oxidation into the soil could be increased in all treatments compared to the pure soil. Biomass growth of Lolium perenne in a greenhouse experiment could be increased significantly only with biochar amendment. If substrates were top dressed in the field, there were significant reductions of CO₂ emissions from the biochar treatment but no significant influences on N₂O and CH₄ fluxes. A significant reduction in biomass growth was found in the vapochar amended plots half a year after initiation of the experiment. Concerning ammonia emissions of the substrate-slurry mixes, we observed significantly higher emissions from the feedstock and biochar treatments, compared to the control.

Title: The Role of Minerals in Enhanced Biochar Performance at Low Application Rates
Authors: Chee H. Chia ¹, Zakaria M Solaiman ², Stephen Joseph ¹, Ellen R. Graber ³, Yun Lin ¹, James Hook ⁴, Paul Blackwell ⁵, Bhupinderpal Singh ⁶, Scott Donne ⁷, Paul Munroe ^1,*
Affiliations: ¹ School of Materials Science and Engineering, University of New South Wales, Sydney, NSW2052 Australia
² Soil Biology Group, School of Earth and Environment (M087), UWA Institute of Agriculture, Faculty of Natural and Agricultural Sciences, The University of Western Australia, CRAWLEY, WA6009 Australia
³Institute of Soil, Water and Environmental Sciences, The Volcani Center, Agricultural Research Organization, POB 6, Bet Dagan 50250, Israel
⁴ NMR Facility, Analytical Centre, University of New South Wales, SYDNEY, NSW2052 Australia
⁵ Department of Agriculture and Food Western Australia, Geraldton Regional Office, WA 6530, Australia
⁶ NSW Department of Primary Industries, P.O. Box 100, Beecroft, NSW 2119, Australia
⁷ Discipline of Chemistry, University of Newcastle, Callaghan, NSW 2308, Australia
Abstract: Biochar is a carbon-rich solid material that can, potentially, increase crop yields, but the often heavy application rates (>5 t ha⁻¹) suggest that biochar is still not an economically viable option to be commercially applied to agricultural activities. It is hypothesised that an enhanced biochar, which is able to increase crop yields at low application rates,  can be synthesised by mixing biochars with manures, minerals, and clays and heating the mixture at low temperatures (up to 220 °C). This treatment will promote bonding between the mineral and the organic carbon phases. This paper describes both the characterization of, and pot trial results for, an enhanced biochar. Examination of the enhanced biochar shows that it has high concentrations of exchangeable cations, available phosphorus, and high acid neutralizing capacity. Structural analysis of the enhanced biochar reveal a microstructure that suggests that bonding has indeed occurred between the biochar and mineral phases. Pot trials show an increase in shoot, root and total plant dry weight after low applications rates (100–200 kg ha⁻¹) of enhanced biochar. It was concluded that enhanced biochar can replace, in part, fertilizers in agricultural applications.

Type of Paper: Article
Title: No Effect Level of Biochar and Compost on Plant Growth of Oats [Avena sativa L.] and Soil Properties under Greenhouse Conditions
Authors: Hardy Schulz¹, Gerald Dunst² and Bruno Glaser¹
Affiliations: ¹ Soil Biogeochemistry, Martin-Luther-University Halle-Wittenberg, von-Seckendorff-Platz 3, 06120 Halle, Germany
² Sonnenerde, Oberwarterstraße 100, A-7422 Riedlingsdorf, Austria
Abstract: It is claimed that biochar addition to soil improves C sequestration, soil fertility and plant growth, especially when combined with organic fertilizers such as compost. However, yet little is known about minimum addition amounts of biochar compost mixes for agricultural purposes. This greenhouse study was carried out to examineeffects of co-composted biochar on oat (Avena sativa L.) yield in both sandy and loamy soil. The aim of this study was to test whether biochar effects can be observed at very low biochar concentrations. To test a variety of application amounts below 3 Mg biochar ha−1, we co-composted five different biochar concentrations (0, 3, 5, 10 kg Mg−1 compost) which were applied at five application amounts (10, 50, 100, 150, 250 Mg ha−1 20 cm−1). Effects of compost addition on plant growth, TOC, Ntot, pH and soluble nutrients outweighed the effects of the minimal biochar amounts in the composted substrates so that a no effect level of biochar of at least 3 Mg ha−1 could be estimated. Along with our detailed setup we also tested a commercial product (Palaterra) which showed significantly weaker performance regarding plant yield, soil reaction and all nutrient contents.