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BNNZ Miscanthus Biochar Project

TL: FAR miscanthus (still too green)
TR: baled miscanthus, Co/ MiscanthusNZ
BL: flame-cap trench production
BR: miscanthus biochar

Report Co/ Dennis Enright, BNNZ chair

“A plot of mature miscanthus growing at the FAR research centre at Tamahere was offered to BNNZ members to use for a biochar production demonstration and biochar yield assessment.
Miles Pope, Simon Day and Dennis Enright for BNNZ and Peter Brown of MiscanthusNZ met on site on May 21st . We intended harvesting some miscanthus and taking it back to Miles’ yard at Pukekohe to pyrolyse in an open trench as we see this could be an approach that farmers might use.
However we found that the miscanthus still had a high moisture content with tops that were still green, which made it unsuitable for trench flame-cap pyrolysis. It is likely to be August before it is sufficiently dry to pyrolyse, so we will not be using it for demonstration purposes.
Peter had already offered us some bales of dry miscanthus (harvested more than a year ago) so we collected two big circular bales weighing 220 kg and 240 kg with a total estimated volume of 3 cubic metres.
Miles dug a trench with his digger, having dimensions about 0.9 m wide, 0.6 m deep and 4 m long. We then began a fire in the bottom of the trench, and over about 1.5 hours we fed all the miscanthus into the trench. The miscanthus readily pyrolysed and was quenched with water at the conclusion. We produced approximately 1.5 m3 of biochar.”

BNNZ are now hoping that the deferred production of biochar from the FAR block will be progressed after August and that this may lead to crop field trials.

BNNZ press release on budget

Biochar Network New Zealand (BNNZ) is delighted to hear the government announce in their budget further funding to assist farmers to respond to the impacts of global warming. Continuing with their commitment to moving towards a low carbon economy, providing additional funding to more sustainable land management will be of great benefit to farmers while also enhancing our international trading relationships and local environment.

BNNZ see biochar as one of the tools that can contribute to more sustainable land management. It provides multiple benefits to soil, while increasing fertiliser efficiency and nutrient retention, so reducing the quantity of fertiliser needed as well as reducing losses into waterways and other sensitive ecosystems.

The October 2018 IPCC special report highlighted Biochar (pyrolysis carbon capture and sequestration) as a key negative emissions technology to remove carbon dioxide from the atmosphere. The IPCC notes that even massive reductions in carbon emissions will be inadequate to achieve carbon neutrality by 2050. It notes that there is additional need for large-scale atmospheric carbon dioxide removal to prevent overshooting the 1.5°C temperature threshold. While increased forestry plantings will help, forestry carbon sequestration has land availability limits. Biochar technology is New Zealand’s biggest single technological opportunity to sequester carbon in soils for the long term while also achieving other productivity and environmental benefits.

Now is the time for NZ government policy to include biochar in Zero Carbon legislation, as well as to provide support for programs that assist large scale production and use of biochar in mainstream farming practice.

For further information email info@bnnz.org.nz


Burn… NZ Pre-order

The new book by Albert Bates and Kathleen Draper has been getting rave reviews from inside and outside the international biochar community. I tried to buy online but the shipping costs more than double the price. I’ve been in touch with Kathleen and the book editor. It seems they are planning a print run in Australia in paper-back. I’ve told them that I will try to gather a bulk order for NZ to reduce the price. This could also end up being under the wing of BNNZ but this is still to be agreed.

Send me an email if you are interested in getting a copy via this route: trevor(at)soilcarbon.org.nz

A bit on biochar

This video is available from the Royal Society of NZ website. I provided notice of this on the ABE FB page back on 9 March 2018, as I was aware that Annette Cowie was a speaker and she has been very active in biochar research in Australia. Annette manages to squeeze in comments on biochar about 3 times (19min, 34min, 57min) but the the talk is well worth a watch, despite the many missed opportunities to discuss biochar in more depth.

Note that NZGRC were co-sponsor for the event. I’ve been critical about their (apparent lack of) interest in biochar. We need to keep waving a black flag but it seems no one is seeing it. We need to be standing on higher ground… which could be better (any!) coverage by NZ media and journalism. My hope lies in BNNZ attracting more resources and folk with time and energy.

Small farm biochar

We are on 7 hectares in Pukekohe, just south of Auckland, New Zealand. The property is a former kiwifruit orchard with a small woodlot in a gully at the rear of the property. Soils are highly productive and much of the area is devoted to vegetable production, especially potato, onion and brassicas.

We have planted a trial orchard of 50 avocado trees, variety Hass with Bacon pollinators. Because the soil bulk density is 1.0 and Avocados prefer lighter soil, we have used biochar to try and ‘lighten’ the soil and to improve drainage and biological activity. First the orchard was ploughed and then graded into berms, just off contour for drainage. A cover crop was grown until compost, gypsum and biochar were added to the soil and rotary hoed in. Satellite photos taken the day we rotary hoed the soil prior to planting show how dark the soil is now compared to our neighbours.

Just after planting showing partially rotted wood mulch used
Soil after incorporation of biochar, gypsum and compost

Trees were planted March 2018 and the soil mulched using rotted wood mulch from an arborist. They suffered in cold wet conditions for winter 2018 and some were grazed by escaped cattle, but the trees are now growing strongly as of Feb 2019. A few have their first fruit, but these have been taken off. We have begun to inter-plant with Tamarillo to fill the gaps until the avos get bigger and about half of the trial planting have done well, quarter have died and quarter are struggling. I put this down to weeds as they weren’t weeded when we were away for 6 weeks.

Ducks with biochar in pond and on the ground

We continue to make biochar using an old bath. Timber that is too small or rotten for fire wood or otherwise useless gets used. Mostly it comes from thinning the woodlot and sawmill waste. The main criteria for me is it has to give a decent volume of char and not require much work to do it.

Almost done. Will be quenched by filling the bath with water.

I get a bathtub full of char each time which goes into the chicken house. After a few months of adding char every few weeks, we shovel it out and either compost it or rotary hoe it into garden beds. We don’t plant directly into those beds for a while.

It is burning the enamel off the bath now after a few burns but is a handy size, easy to quench and more tolerant of wet wood etc. I have soaked the char in duck pond water as well which gets it going biologically. I have pretty much given up on the TLUD. Too much time cutting up timber to fit and I always forget it and return to a pile of ash.

Press Release – BNNZ IGM

The following press release will be circulated this week to various media publications in NZ. Your help with its circulation and dissemination would be appreciated.


In a world having too much carbon in the atmosphere and obsessed about expensive and dangerous technologies for it’s removal, it is comforting to know that a form of charcoal has now been accepted by the IPCC as a useful tool in the fight against climate change.

Biochar is charcoal which can be used to lift productivity in agriculture and as a long-lived carbon store in soils. It can be used to enhance water quality and as a bioremediation tool for contaminated soils. The production of biochar can also deliver secondary bioenergy benefits and deal with many types of ‘liability’ biomass. Biochar has attracted worldwide attention as a Negative Emissions Technology (NET) in the latest IPCC report, presented at COP24. Biochar has been identified as having positive impacts on 12 of the 17 UN Sustainable Development Goals.

A growing number of New Zealand farmers are becoming interested in making and using Biochar, leading to a new organisation is being formed, Biochar Network New Zealand (BNNZ), which will have its Inaugural General Meeting in Pukekohe on 14 February.

BNNZ is planning to promote and support activities that provide widespread awareness, understanding and acceptance of Biochar in New Zealand, leading to a diverse range of production and application scenarios for the benefit of New Zealand’s agriculture, industry and environment.

The BNNZ IGM will take place at 10am on 14 February 2019 at the Reid Anderson Lounge, 18 Wesley Road, Pukekohe.

If you wish to attend, or participate via remote access, please email your request to: BNNZ@soilcarbon.org.nz

For more information about biochar please see:

BNNZ mission statement

Plans for the Inaugural General Meeting of Biochar Network New Zealand are progressing. The IGM will take place on 14 February 2019 in Pukekohe. Live streaming technology will be used to allow folk from around the country to attend the meeting remotely. All attendees (physical or remote) will be required to preregister so that we can adequately cater for numbers.

A press release is being prepared and, as part of this, a ‘BNNZ Mission Statement’ may be helpful. Your comments or alternative text on the draft below would be appreciated…

BNNZ: promote and support activities leading to widespread awareness, understanding and acceptance of biochar in New Zealand, leading to a diverse range of production and application scenarios for the benefit of New Zealand’s agriculture, industry and environment.

NZ links in China research

Insight into the effects of biochar on manure composting: Evidence supporting the relationship between N2O emission and denitrifying community(Article)

  • aInstitute of Environmental Science and Technology, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China
  • bCallaghan Innovation Research Ltd, University of Canterbury, Private Bag 4800, Christchurch, 8140, New Zealand
  • cSchool of Environmental and Resource Sciences, Zhejiang A and F University, Lin’an, Hangzhou 311300, China


Although nitrous oxide (N2O) emissions from composting contribute to the accelerated greenhouse effect, it is difficult to implement practical methods to mitigate these emissions. In this study, the effects of biochar amendment during pig manure composting were investigated to evaluate the inter-relationships between N2O emission and the abundance of denitrifying bacteria. Analytical results from two pilot composting treatments with (PWSB, pig manure + wood chips + sawdust + biochar) or without (PWS, pig manure + wood chips + sawdust) biochar (3% w/w) demonstrated that biochar amendment not only lowered NO2 -N concentrations but also lowered the total N2O emissions from pig manure composting, especially during the later stages. Quantification of functional genes involved in denitrification and Spearman rank correlations matrix revealed that the N2O emission rates correlated with the abundance of nosZ, nirK, and nirS genes. Biochar-amended pig manure had a higher pH and a lower moisture content. Biochar amendment altered the abundance of denitrifying bacteria significantly; less N2O-producing and more N2O-consuming bacteria were present in the PWSB, and this significantly lowered N2O emissions in the maturation phase. Together, the results demonstrate that biochar amendment could be a novel greenhouse gas mitigation strategy during pig manure composting.

Peter Winsley on climate change

A thoughtful new essay on climate change… and a mention on biochar.

Peter has a long history with biochar in NZ, dating back (at least) to the his 2007 paper ‘Biochar and bio-energy production for climate change mitigation‘ when he was with MAF. This paper is still quoted extensively in other research papers and is listed in the wikipedia references on biochar.

I’m no expert on the history of biochar interest in NZ, but I believe Peter was involved with early govt work that led to initial investment in NZBRC.