New NZ paper on soil carbon mentions biochar

It would be great to get access to this report and assess their conclusion that “Biochar addition could possibly increase soil carbon stocks but it is not yet an economical option for large-scale application in New Zealand.

Management practices to reduce losses or increase soil carbon stocks in temperate grazed grasslands: New Zealand as a case study


•We review farm management options to increase grassland soil carbon stocks.
•Carbon saturation deficit defines the potential to increase soil carbon stocks.
•Increasing carbon stock is dependent on carbon inputs and stabilisation processes.
•Models highlight trade-offs between increasing soil carbon and milk production.
•We recommend assessment criteria and priorities for further research.


Even small increases in the large pool of soil organic carbon could result in large reductions in atmospheric CO2 concentrations sufficient to limit global warming below the threshold of 2 °C required for climate stability. Globally, grasslands occupy 70% of the world’s agricultural area, so interventions to farm management practices to reduce losses or increase soil carbon stocks in grassland are highly relevant. Here, we review the literature with particular emphasis on New Zealand and report on the effects of management practices on changes in soil carbon stocks for temperate grazed grasslands. We include findings from models that explore the trade-offs between multiple desirable outcomes, such as increasing soil carbon stocks and milk production.

Farm management practices can affect soil carbon stocks through changes in net primary production, the proportions of biomass removed, the degree of stabilisation of carbon in the soil and changes to the rate of soil carbon decomposition. The carbon saturation deficit defines the potential for a soil to stabilise additional carbon. Earlier reviews have concluded that, while labile carbon is the dominant substrate for soil carbon decomposition, a fraction of soil carbon stocks is stabilised and protected from decomposition by the formation of organo-mineral complexes. Recent evidence shows that the rate of organic carbon decomposition is determined primarily by the extent of soil organic carbon protection and, therefore, the availability of substrates to microbial activity.

New Zealand grassland systems have moderate to high soil carbon stocks in the surface layers (i.e., upper 0.15 m) where most roots are located, so the carbon saturation deficit is relatively low and the scope to increase soil carbon stocks by carbon inputs from primary production may be limited. International studies have shown that the addition of fertilisers, feed imports, and applications of manure and effluent can increase soil carbon stocks, especially for degraded soils, but the responses in New Zealand soils are uncertain because of the limited number of studies. However, recent evidence shows that irrigation can reduce soil carbon stocks in New Zealand, but neither the processes nor the long-term trends are known. Studies of sward renewal have shown that short-term losses of carbon losses resulting from the disturbance can be mitigated using rapid replacement of the new sward, minimum tillage and avoidance of times when the soil water content is high. Swards comprising multiple species have also shown that soil carbon stocks may be increased after periods of several years. Model simulations have shown that the goal of increasing both soil carbon and milk production could be achieved best by increasing carbon inputs from supplementary animal feed. However, losses of carbon at feed export sites need to be minimised to achieve overall net gains in soil carbon. Grazing intensity can have a big influence on soil carbon stocks but the magnitude and direction of the effects are not consistent between studies.

Biochar addition could possibly increase soil carbon stocks but it is not yet an economical option for large-scale application in New Zealand. There is some evidence that the introduction of earthworms and dung beetles could potentially increase soil carbon stabilisation, but the greenhouse gas benefits are confounded by possible increases in nitrous oxide emissions. The new practice of full inversion tillage during grassland renewal has the potential to increase soil carbon stocks under suitable conditions but full life-cycle analysis including the effects of the disruptive operations has yet to be completed.

We conclude with a list of criteria that determine the success and suitability of management options to increase soil carbon stocks and identify priority research questions that need to be addressed using experimental and modelling approaches to optimise management options to increase soil carbon stocks.

Report from the (bio)coal-face in Otago

We met Ben Elms recently in Cromwell when he attended our first workshop on 24 May. He had already begun his journey into biochar production and applications. Here is his report from the front line in Otago…

“I got in touch directly with the Ithaka institute after doing some research and deciding I wanted something with a little scale for a kiln. They were kind enough to send me the plans. A Local engineer friend made the Kiln and is about to make a second for a friend. We designed it so it can be easily moved around the property or onto a trailer to take off site. May need to make some modifications for getting it off the trailer the other end.

I proceeded to do 2 burns over 2 days. Using wooden pallets with HT stamp for heat treated. The MB stamped put aside not to be burnt. (methyl bromide treated). Pine brash, broom, prunings, old rotten timber… what ever was easy to access. Going forward I will create a dedicated spot for all this.
Burns went really well. If I ever smothered the fire cap with to much material the broom tops was fantastic to fire it up and keep the fire cap burning well. Generally I would alternate the layers with bigger timber with a layer of smaller diameter timber/brash. Each burn took 5 hrs start to finish.
With the tap at the bottom of the kiln, extinguishing the burn was very easy. The water tote had an old smelly seaweed brew added to it as well as as some liquid humates I had lying around.  The top of the brew was extinguished with a chicken manure slurry and horse manure slurry.
Anything that didn’t char in the first burn went into the second burn. 
Its amazing how much moisture is held in the char. You think its dry but when the biochar is put through the wood chipper the biochar is very damp to wet. If you like your woodchipper to look sparkly then don’t put biochar through it. Looking forward to having lots more burns and experimenting with different quenching brews and different post burn treatment of the biochar. Feel free to contact me for more info/questions.”
Ben sent me more pics … here is a link to the folder where I’ve stored them. We are hoping a local biochar community group will coalesce around the work of Ben and others that attended the Otago workshop. More reports on the workshops are… coming soon
We would welcome more news and stories like this from around NZ…

Cadmium soil contamination in NZ

I think the following should be of interest in NZ based on the levels of Cd contamination in some of our soils. There are other similar research finding coming from China. I posted a link to a NZ PhD thesis on the contamination issue in April at the ABE FB page that fails to mention biochar as a potential solution.

The effect of several activated biochars on Cd immobilization and microbial community composition during in-situ remediation of heavy metal contaminated sediment


Chemical activation and microwave assisted activation were adopted to modify biochar. Activated biochars were characterized by SEM, BET, FTIR, XRD and XPS. Raw biochar, activated biochars and commercial activated carbon were compared as remediation strategies for sediment from the Xiangjiang River containing 14.70 mg/kg Cd. After the treatment by activated biochar, the overlying water and pore water concentration of Cd decreased by 71% and 49%, respectively. And the threat of heavy metal along with bioavailability of Cd was depressed. Moreover, the immobilsation of Cd in sediment was related to BET surface area and the content of oxygen containing functional groups of activated biochars. Furthermore, a PCR-DGGE-based experiment was performed for the detection of microbial community. The indigenous microbial community was affected and new microbial community appeared after treat by activated biochar. Activated biochar can be used as an inexpensive and efficient in situ remediation material of sediment containing metal.

Biochar workshop near Nelson

The biochar workshop tour finished in Gisborne on Friday. The tour was an intense 3 weeks of travel and action leaving behind a long trail of followup actions and emails. And no time for the monthly newsletter. It will take some time to catch up… and now the Feildays starts Wednesday and we hope to be waving a black flag there as well…

This report has been forwarded by the biochar community group based on Motueka, Carbon Action Aotearoa…

Dennis and I are very grateful for their support during our stay for the Nelson workshop and the preceding public forum in Motueka that CAA organised.

More on this and the other workshops soon.

Click on image to link to the cutting or you can search for it here (page 20)


Carbon Action Aotearoa event in Motueka, 28May

A click on the image opposite should lead to a legible version of this article, published in the Nelson leader on 17 May.

We’ve been getting great support from CAA in Motueka for the Nelson workshop on 29 May. Katerina and her team are organising a free public forum on the evening before the workshop.

Details: Free one-hour biochar introductory evening: Monday 28th May 7.30 pm at MOTEC, Parklands School, opposite the library in Pah St. Motueka. (Koha for refreshments and venue hire welcome).

Biochar and kiwifruit industry

Zespri have been kindly supporting our efforts to educate and inform the kiwifruit industry on opportunities related to biochar production and application.

They have published a short article in their latest industry magazine (linked from their banner, above).

Zespri have recently provided some support to research related to biochar through a Waikato University internship but they are not endorsing the use of biochar products.

The nascent biochar industry needs to work with agriculture industries in NZ to validate claims and ensure safe application of new products. Hopefully, the research community will also become more active and interested but this may only come from more funding.

HortNZ… followup article

Biochar: the renaissance of an ancient practice for a sustainable future

HortNZ have kindly supported our workshop marketing activity with the inclusion of a followup story  to the Robin Boom article published in their January edition of their magazine, NZGrower. I covered that in an earlier post:

You can access a copy of the article from the page links below.

click to link to PDF page

NZGrower Vol.73-03, pg30

click to link to PDF page

NZGrower Vol.73-03, pg31

OWNZ publishes biochar article

Reviving an ancient soil technology: Biochar

Organic Winegrowers NZ magazine

Biochar article

Organic Winegrowers NZ have published an article in their latest “organic matters” magazine focused on biochar and supporting the biochar workshop tour coming up next month. All of the workshops are in wine or vine country…

You can access the article pages from the magazine by clicking on the adjacent cover image or the article title, above.

Pukekohe biochar on Earth Day

Source: Pukekohe charcoal fire event to make biochar on Earth Day |

“The Pukekohe Anglican Parish is hosting a charcoal fire event for Earth Day on April 22, as part of the Anglican’s Action Network. The event, held at Pukekohe’s St Paul’s Anglican Church on Buckland Rd, will see a one kilogram block of wood burned for each person in attendance, to make biochar, which will be buried, with fruit trees planted on top. This technique reduces greenhouse emissions by avoiding the release of carbon as the wood decays. To place a block of wood on the fire and to learn more about biochar, the event will take place from 9-11am, followed by a sausage sizzle at 11.30am and the planting of the trees at 12.30pm. A gold coin donation is asked for, to help the parish continue its sustainability work. For more information call John, 2381357.”

BiogroNZ support for biochar workshops

And while I’m on the workshop article theme (last two posts), Biogro have also come out in support with a banner in their latest (March) newsletter. I can’t find a newsletter archive on their website so the best I can do is a C&P from my email newsletter copy:As the text is illegible!:

“Rebuilding and retaining carbon in the soil is fundamental when farming organically. Returning organic matter of various types to the soil is a mandatory and standard process. In line with this is using biochar, which is charcoal produced for application to soil. Workshops are being held across May/June 2018 with a collaboration between AllBlackEarth and NZ Biochar to present information and demonstrations on making and using Biochar. For all inquiries and to make a booking, head to the AllBlackEarth events website.”

Note that the link provided in their newsletter was faulty (corrected, above).