Recent biochar research articles

Liang, Yuan; Cao, Xinde; Zhao, Ling; Xu, Xiaoyun; Harris, Willie (2014). “Phosphorus Release from Dairy Manure, the Manure-Derived Biochar, and Their Amended Soil: Effects of Phosphorus Nature and Soil Property.” Journal of Environmental Quality 43:1504–1509. DOI: 10.2134/jeq2014.01.0021

Abstract: Land application of animal manure often risks excessive phosphorus (P) release into the surrounding water. The aim of this study was to convert the dairy manure into biochar, followed by their application into soil, and then to investigate P release from the manure and its derived biochar as well as from the manure- and biochar-amended soil. The results showed that P release was reduced when the manure was converted into biochar due to formation of less-soluble whitlockite [(Ca, Mg)3(PO4)2]. The cumulative P released from biochar over 240 h was 0.26 g kg−1, a 76% reduction of that from the manure (1.07 g kg−1). The kinetic release of P from the manure was determined by the fast desorption process and was better fitted to Elovich equation, whereas P release from biochar was initially controlled by the diffusion process and then by slow but steady dissolution of (Ca,Mg)3(PO4)2, following the parabolic diffusion and linear models, respectively. When the manure or biochar was incorporated into the soil, P release in the CaCl2 and simulated acid rain water extraction from biochar-amended soil was consistently lower than that from the manure-amended soil during 210-d incubation. The lower P release in the biochar-amended soil was determined by stable P form (Ca, Mg)3(PO4)2 in the biochar itself, but less from the soil property effect. Results indicated that initial high P release from manure can be mitigated by converting the manure into biochar.

Eykelbosh AJ, Johnson MS, Santos de Queiroz E, Dalmagro HJ, Guimarães Couto E (2014). Biochar from Sugarcane Filtercake Reduces Soil CO2 Emissions Relative to Raw Residue and Improves Water Retention and Nutrient Availability in a Highly-Weathered Tropical Soil. PLoS ONE 9(6): e98523. DOI: 10.1371/journal.pone.0098523

Abstract: In Brazil, the degradation of nutrient-poor Ferralsols limits productivity and drives agricultural expansion into pristine areas. However, returning agricultural residues to the soil in a stabilized form may offer opportunities for maintaining or improving soil quality, even under conditions that typically promote carbon loss. We examined the use of biochar made from filtercake (a byproduct of sugarcane processing) on the physicochemical properties of a cultivated tropical soil. Filtercake was pyrolyzed at 575°C for 3 h yielding a biochar with increased surface area and porosity compared to the raw filtercake. Filtercake biochar was primarily composed of aromatic carbon, with some residual cellulose and hemicellulose. In a three-week laboratory incubation, CO2 effluxes from a highly weathered Ferralsol soil amended with 5% biochar (dry weight, d.w.) were roughly four-fold higher than the soil-only control, but 23-fold lower than CO2 effluxes from soil amended with 5% (d.w.) raw filtercake. We also applied vinasse, a carbon-rich liquid waste from bioethanol production typically utilized as a fertilizer on sugarcane soils, to filtercake- and biochar-amended soils. Total CO2 efflux from the biochar-amended soil in response to vinasse application was only 5% of the efflux when vinasse was applied to soil amended with raw filtercake. Furthermore, mixtures of 5 or 10% biochar (d.w.) in this highly weathered tropical soil significantly increased water retention within the plant-available range and also improved nutrient availability. Accordingly, application of sugarcane filtercake as biochar, with or without vinasse application, may better satisfy soil management objectives than filtercake applied to soils in its raw form, and may help to build soil carbon stocks in sugarcane-cultivating regions.
Hao Sun, Catherine Elizabeth Brewer, Caroline A. Masiello, and Kyriacos Zygourakis (2015). “Nutrient Transport in Soils Amended with Biochar: A transient model with two stationary phases and intraparticle diffusion. Industrial & Engineering Chemistry Research Just Accepted Manuscript. DOI: 10.1021/ie503893t

Abstract: We present the development of a rate model that simulates nutrient transport in soils amended with biochar. The model considers two stationary adsorbent phases (biochar and soil), axial dispersion, interphase mass transfer and intraparticle diffusion. Langmuir isotherms govern the local equilibria between the solute diffusing in the liquid-filled pores and adsorbed on the pore surfaces of biochar and soil particles. We demonstrate that addition of biochar can effectively slow nutrient transport through the soil if the biochar/soil ratio and crucial biochar properties (like its adsorption capacity and affinity to the sorbate) are carefully matched to the soil properties (water velocity, soil type) and the amount of rainfall or irrigation. Simulations can also track the spatial and temporal evolution of nutrient concentration profiles, information that is essential for analyzing and interpreting experimental data. The new model can be a valuable tool for fine-tuning the production and use of biochar.

Zhang Q-z, Dijkstra FA, Liu X-r, Wang Y-d, Huang J, et al. (2014) Effects of Biochar on Soil Microbial Biomass after Four Years of Consecutive Application in the North China Plain. PLoS ONE 9(7): e102062. DOI: 10.1371/journal.pone.0102062

Abstract: The long term effect of biochar application on soil microbial biomass is not well understood. We measured soil microbial biomass carbon (MBC) and nitrogen (MBN) in a field experiment during a winter wheat growing season after four consecutive years of no (CK), 4.5 (B4.5) and 9.0 t biochar ha−1 yr−1 (B9.0) applied. For comparison, a treatment with wheat straw residue incorporation (SR) was also included. Results showed that biochar application increased soil MBC significantly compared to the CK treatment, and that the effect size increased with biochar application rate. The B9.0 treatment showed the same effect on MBC as the SR treatment. Treatments effects on soil MBN were less strong than for MBC. The microbial biomass C:N ratio was significantly increased by biochar. Biochar might decrease the fraction of biomass N mineralized (KN), which would make the soil MBN for biochar treatments underestimated, and microbial biomass C:N ratios overestimated. Seasonal fluctuation in MBC was less for biochar amended soils than for CK and SR treatments, suggesting that biochar induced a less extreme environment for microorganisms throughout the season. There was a significant positive correlation between MBC and soil water content (SWC), but there was no significant correlation between MBC and soil temperature. Biochar amendments may therefore reduce temporal variability in environmental conditions for microbial growth in this system thereby reducing temporal fluctuations in C and N dynamics.

Keith Jones, Girish Ramakrishnan, Minori Uchimiya, and Alexander Orlov (2015). “New Applications of X-ray Tomography in Pyrolysis of Biomass: Biochar Imaging.” Energy & Fuels Just Accepted Manuscript. DOI: 10.1021/ef5027604.

Abstract: We report on the first ever use of non-destructive micrometer-scale synchrotron-computed microtomography (CMT) for biochar material characterization as a function of pyrolysis temperature. This innovative approach demonstrated an increase in micron-sized marcropore fraction of the Cotton Hull (CH) sample, resulting in up to 29% sample porosity. We have also found that initial porosity development occurred at low temperatures (below 350°C) of pyrolysis, consistent with chemical composition of CH. This innovative technique can be highly complementary to traditional BET measurements, considering that Barrett-Joyner-Halenda (BJH) analysis of pore size distribution cannot detect these macropores. Such information can be of substantial relevance to environmental applications, given that water retention by biochars added to soils is controlled by macropore characteristic among the other factors. Complementing our data with SEM, EDX and XRF characterization techniques allowed us to develop a better understanding of evolution of biochar properties during its production, such presence of metals and initial morphological features of biochar before pyrolysis. These results have significant implications for using biochar as a soil additive and for clarifying the mechanisms of biofuel production by pyrolysis.

New biochar publication from ISTC

Sorption of Polycyclic Aromatic Hydrocarbons (PAHs) to Biochar and Estimates of PAH Bioavailability

Biochars were produced by slow pyrolysis of corn stover under a nitrogen atmosphere at 450°, 550°, and 750°C. The chars were subjected to artificial aging, i.e., repeatedly freezing and thawing or incubating moist char at 60° and 110°C. A total of 12 materials was produced and characterized. The total polycyclic aromatic hydrocarbon (PAH) contents of 450° and 550° chars were 1.4 and 0.2 mg kg-1, respectively. Extraction and analysis of PAHs in the 750° char was performed, however the quality control associated with this assay indicated that PAHs could not be quantitatively extracted from this material by standard methods. Sorption and mild extraction experiments were performed. Mild extraction with 2- hydroxypropyl-β-cyclodextrin (HPCD), mimics bioaccessibility. Pyrene was used as a probe compound. The sorption data were well described by Freundlich isotherms. Pyrene sorption was strong for all chars, with the amount sorbed at 1μg L-1 dissolved pyrene ranging from 10 to the 6th to over 10 to the 7th μ g kg-1. The pyrene content of the chars was too low to be detected in the HPCD extracts, so the chars were spiked with pyrene and allowed to equilibrate before extraction. Only 10 to 15% of added pyrene was HPCD-extractable from the 450° char and 1 to 5% from the 550° and 750° chars. Aging had small but measureable effects on both sorption and HPCD extraction of pyrene.

Seeking Sustainability at Duke Campus Farm

Read the full story from Duke University.

What if you could supply everything your garden needs to produce a robust crop of veggies without buying a single bag of fertilizer? That’s a question Duke senior Anne Martin has tackled in a year-long independent study project.

“The Duke Campus Farm is a very sustainable organic farm, yet we currently have to bring in all of our soil amendments, such as fertilizers or mineral inputs, in bags from off the farm. It’s frustrating to have to rely on products when we don’t really know how they’re procured, produced or transported,” Martin said. “It’d be great to be able to produce our own organic soil amendments, on-site and cost-effectively.”

Martin is testing the potential of biochar – pulverized charcoal produced by burning downed trees, branches, chicken litter and other organic material – as an alternative to more conventional amendments. She is studying whether biochar can increase soil quality, water and nutrient retention and ultimately, crop production. Studies have suggested that biochar could be a low-cost, sustainable option for farmers, in particular those with limited resources, and may even be a good tool to sequester carbon, a strategy to help mitigate global warming.

Study highlights biochar’s potential in horticulture

Read the full story from the Soil Science Society of America.

Interest has never been higher in adding charcoal, or “biochar,” to agricultural systems, where it’s touted as a way to boost the soil’s water-holding capacity, reduce the need for fertilizer, and counter climate change. But so far, biochar has gotten relatively little attention in the horticultural and growth media industries.

That could change. Research led by Reza Nemati of the growth media company, Fafard & Frères, in Quebec, Canada, suggests that biochar could be a good replacement for perlite and to a lesser extent, peat moss. However, several questions still need answering before biochar enjoys widespread adoption in horticulture.

The study appears in the November 2014 issue of the Vadose Zone Journal.

Researcher Finds Inexpensive, Easy Way to Filter Arsenic From Water

Read the full story from the University of Florida.

A University of Florida professor has developed a quick, cheap and easy way to filter from water one of the world’s most common pollutants: arsenic.

Bin Gao’s team used iron-enhanced carbon cooked from hickory chips, called biochar, to remove the toxin. He is an associate professor with the Institute of Food and Agricultural Sciences’ in agricultural and biological engineering…

In a study to be printed in the January issue of the journal Water Research, Gao and his team describe the process: The wood chips were first ground, then heated in nitrogen gas, but not burned. The resulting biochar, which has the consistency of ground coffee, was then treated with a saltwater bath to impregnate it with iron. Tests showed that plain biochar had no effect on arsenic, but the iron-enhanced product effectively removed the poison from water.

Removal of Chlorophenols by Biochar

Read the project summary from the University of Edinburgh School of Engineering.

This project aims at identifying the mechanisms involved during the removal of different types of chlorophenols using several biochars during water treatment. Chlorophenols and biochars with different physico-chemical properties will be tested as well as different environmental characteristics.