Biochar & nutrient transport

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 This looks relevant to biochar nutrient management in NZ pastoral farming. No access so can’t be sure that the nutrient focus includes N.

Nutrient Transport in Soils Amended with Biochar: A transient model with two stationary phases and intraparticle diffusion

“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.”

Scientist wanted: Soil Carbon

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Applications for this post are now closed but I would guess it is a positive news story for biochar research in NZ. It would be hard to imagine that this work could be progress without the inclusion of more biochar research.

Post-Doctoral Scientist: Soil Carbon

Three year fixed term

Lincoln – Vacancy 9545

The Soil, Water & Environment Group works with land-based industries to develop the knowledge and tools needed to promote economically and environmentally sustainable management and use of soil and water resources in agricultural and horticultural production systems.

Developing long-term sustainable strategies for increasing soil carbon depend on understanding the key factors that affect soil organic carbon (SOC) stabilisation. We seek to understand the principal mechanisms that affect soil carbon stabilisation and to develop methods to determine the stabilisation capacity and vulnerability of soil carbon loss. These methods will be applied to identify those soils that have the greatest potential to stabilise additional SOC and land use practices that enhance SOC stabilisation.

In this three year post-doctoral appointment you will play a lead role in delivering research to:
• Identify the physical and chemical properties that affect soil carbon stabilisation in a wide range of New Zealand soils
• Develop improved methods to predict the carbon stabilisation capacity of New Zealand soils
• Synthesise findings from available studies to identify land use practices that affect soil carbon stabilisation and the potential for soil carbon sequestration.

The research will be funded by the New Zealand Agricultural Greenhouse Gas Research Centre (NZAGRC) and will involve close collaborations with scientists from AgResearch Ltd, Massey University and CSIRO Land and Water.

Biochar meta-analysis on Nitrous Oxide

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The molar H:Corg ratio of biochar is a key factor in mitigating N2O emissions from soil

Highlights

•An updated meta-analysis including 56 studies finds that biochar reduces soil N2O emissions by 49 ± 5%.
•Field studies show lower reductions in N2O emissions (28 ± 16%) compared to laboratory studies (54 ± 5%).
•The lower the biochar molar H:Corg ratio the higher the N2O mitigation.

“A previously published meta-analysis of biochar impacts on soil N2O emissions by Cayuela et al. (2014) found a “grand mean” reduction in N2O emissions of 54 ± 6% following biochar application to soil. Here we update this analysis to include 26 additional manuscripts bringing the total to 56 articles. The updated meta-analysis confirms that biochar reduces soil N2O emissions by 49 ± 5% (mean ± 95% confidence interval). Importantly, this meta-analysis has sufficient data to investigate the impact of biochar under field conditions, showing a statistically significant lower average reduction in the field (28 ± 16%) compared to controlled laboratory studies (54 ± 3%). A key finding is the importance of the molar H:Corg ratio of biochar in determining mitigation of N2O. Biochars with a molar H:Corg ratio <0.3, indicative of a high degree of aromatic condensation, lowered N2O emissions by 73 ± 7% while biochars with a molar H:Corg ratio >0.5 were less effective at 40 ± 16%. Together with previously published information, our new results suggest that a key mitigation mechanism is linked to the degree of polymerization and aromaticity of biochar.”

It would be great to see some comment from the NZ Agriculture Greenhouse Gas Research Centre on this meta-analysis in the context of their plans for future work with nitrous oxide and soil carbon.

Congratulations Marta: IBI chair

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Congratulations to Marta Camps Arbestain, Associate Professor Biochar & Soil Science Research at Massey University, who has been appointed as Chair for the IBI board. It is an impressive lineup of biochar experts on the board.

The only NZ connection on the Advisory Committee is Hailong Wang, Zhejiang A & F University, China, who was working with biochar as part of his previous position with Scion in NZ.

New Biochar Journal article

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Campfire Lessons: Breaking Down the Combustion Process to Understand Biochar Production

By Mark R. Fuchs, M. Garcia-Perez, P. Small and G. Flora

“Campfires were the first step in the evolution of slow pyrolysis reactors. Observing the play of the flames while sitting around a campfire is still one of the best possible lessons to understand the main principles of pyrolysis. Mark Fuchs and colleagues bring the different natural phenomenon of the fire into context of modern pyrolysis.” …

Reviewer comment

Catherine Brewer:

One of the frequent challenges experienced by members of the biochar community is figuring out how to explain biochar and biomass thermochemical processes to friends and family members. The authors’ use of the campfire illustration is so helpful because it is familiar to a wide audience and scientifically accurate at the same time. After hearing this illustration the first time myself, I remember thinking, “I will never again see just a campfire.”

The future of wood

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Biochar gets a mention in this NZ Herald article Co/ Tim Langley at Carbonscape…

The power of biochar

“Executive director of CarbonScape, Tim Langley, says the real potential technological impact on forestry long-term lies in a product known as biochar. “It’s basically the same product as green coke, but used as a soil amendment, and it has all of those activated carbon aspects of being able to retain moisture really, really well. It also acts as a sort of microbial reef in the ground.”

He says there’s work being done on biochar all over the world, and its impact on forestry globally as a sector is likely to be very large.

“The commercialisation plan is to make those products here in New Zealand, and then export them. Our dream is that they’ll be using our technology in China, and using their own forestry over there.””

NZBRC biochar production thesis

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Design and Characterisation of an ‘Open Source’ Pyrolyser for Biochar Production

This masters thesis from Rhonda Bridges is available for download from here. This batch system was presented to delegates at the last NZBRC workshop by Prof. Jim Jones.

“An ‘open source’ field-scale batch pyrolyser was designed and constructed to produce biochar, which is the solid residue formed when biomass thermally decomposes in the absence of oxygen. The design approach was focused on simplicity for the intended target user, a hobby farmer. This is achieved in a batch process, where temperature ramp rates, gas flows and the end-point are controlled. Solids handling is only required at either end of the process. LPG is used as the initial heating source and later as the ignition source when pyrolysis gases are recycled. A mathematical model formulation of the process was developed to predict the proportions of products produced as well as the time taken to achieve complete pyrolysis. Reaction kinetics are complex and not fully understood. In this model, simplifications were taken to provide guidelines for the reactor design as well as the effects of moisture on the process efficiencies. The quality performance of the ‘open source’ pyrolyser was determined by comparing its biochar to that produced in a lab scale gas fired drum pyrolyser. Parameters varied on the lab drum pyrolyser were highest treatment temperature in the range 300 to 700 °C, sample size, moisture content and grain direction for Pinus radiata. The properties that were investigated are elemental composition (C, H, N, S), proximate analysis (moisture, volatile matter and fixed carbon) and char yield (% wt/wt). The ash content was determined by residue on ignition. For the lab scale experiments, it was found with increasing peak temperature that yield, volatile matter and hydrogen to carbon ratio decrease. Yield was unaffected by moisture, size and grain direction. The design of the pilot reactor followed the principle observed with particle size that, in order to get maximum residence time of the vapour and tar in the reactor, the reactor was designed with a perforated core so that the vapours have a tortuous path of travel. This design also meant that heat and mass transfer occurred in the same direction, from the outer wall to the perforated core. In comparison to the lab scale pyrolyser, the same trends were observed in regards to temperature. High yields of 29.7 wt % and 28.8 wt % were obtained from wood with an initial moisture content of 21.9 wt % and 60.4 wt % respectively, confirming yield is unaffected by moisture. Mass and energy balances were conducted on both the lab scale and pilot scale pyrolysers. For every kilogram of carbon in LPG used on the lab scale pyrolyser, an average of 0.25 kilograms of carbon is produced at 700 °C. Based on the optimum run for the pilot scale, for every kilogram of carbon in LPG used, 2.6 kilograms of carbon is produced at 700 °C.”

Symphony of the Soil

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2015 will celebrate International year of Soils. And did you know that World Soil Day was 5 December…

World soil day

 

 

 

“The 68th UN General Assembly declared 2015 the International Year of Soils. The Food and Agriculture Organization of the United Nations has been nominated to implement the International Year of the Soils (IYS) 2015, within the framework of the Global Soil Partnership and in collaboration with Governments and the secretariat of the United Nations Convention to Combat Desertification.

To help celebrate the International Year of the Soils, we will be streaming the full feature film, Symphony of the Soil, for FREE for the week of December 5 – 12, 2014. You can help us spread the word by linking to or embedding the film on your site with a link to the Symphony of the Soil website and to the International Year of the Soils.”

http://www.symphonyofthesoil.com/

New paper on biochar nutrient & pollution management

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Biochar suppresses N2O emissions while maintaining N availability in a sandy loam soil

  • a Centre for Ecology & Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, LA1 4AP, UK
  • b School of Geosciences, University of Edinburgh, High School Yards, Edinburgh, EH8 9XP, UK
Received 19 May 2014, Revised 13 November 2014, Accepted 16 November 2014, Available online 28 November 2014

Abstract

Nitrous oxide (N2O) from agricultural soil is a significant source of greenhouse gas emissions. Biochar amendment can contribute to climate change mitigation by suppressing emissions of N2O from soil, although the mechanisms underlying this effect are poorly understood. We investigated the effect of biochar on soil N2O emissions and N cycling processes by quantifying soil N immobilisation, denitrification, nitrification and mineralisation rates using 15N pool dilution techniques and the FLUAZ numerical calculation model. We then examined whether biochar amendment affected N2O emissions and the availability and transformations of N in soils.

Our results show that biochar suppressed cumulative soil N2O production by 91% in near-saturated, fertilised soils. Cumulative denitrification was reduced by 37%, which accounted for 85–95 % of soil N2O emissions. We also found that physical/chemical and biological ammonium (NH4+) immobilisation increased with biochar amendment but that nitrate (NO3−) immobilisation decreased. We concluded that this immobilisation was insignificant compared to total soil inorganic N content. In contrast, soil N mineralisation significantly increased by 269% and nitrification by 34% in biochar-amended soil.

These findings demonstrate that biochar amendment did not limit inorganic N availability to nitrifiers and denitrifiers, therefore limitations in soil NH4+ and NO3− supply cannot explain the suppression of N2O emissions. These results support the concept that biochar application to soil could significantly mitigate agricultural N2O emissions through altering N transformations, and underpin efforts to develop climate-friendly agricultural management techniques.