Biochar workshop WS-1 – Cromwell

Dennis Enright produced a report on the May-June biochar workshops soon after the tour was completed. This report was circulated to all participants of the workshops. We are now sharing this post-workshop report as a series of ABE posts.


A 2 year study on the effects of biochar and compost on soil water and nutrient content was conducted in a Mt Difficulty vineyard at Cromwell, Central Otago. Treatments consisted of; pine branch biochar, compost, and mixes of the two, which were buried in a trench midway between grapevine rows. This approach was taken to cause least disruption to the roots of 5 year old vines, and would simulate placement of biochar prior to planting new vines on top of biochar. As there were no or few vine roots in the treatment zone, assessment of the treatment effects was restricted to measuring soil water and nutrient content.

That study showed that a woody biochar (with negligible nutrients) incorporated into  gravelly free draining soil can retain moisture to the same degree as an equivalent amount of grape marc compost. Biochar also had a positive synergistic effect on nutrients supplied by the compost. That is, in the presence of biochar soil nutrient levels remained higher even though the amount of compost applied was reduced.

It is proposed that further simple on farm experiments could provide long term study sites.

So during a series of biochar workshops held at Cromwell, Brightwater, Waihi, Waiuku and Gisborne (May/June 2018) small experimental sites were established using biochar produced during the workshop. At each of these locations the fresh biochar was applied to soil and will be compared with no addition of biochar in a randomised block design replicated 3 times. Samples of the biochars were retained for analyses and in the future other measurements such as soil moisture and nutrient content will be undertaken to evaluate whether there are any benefits, particularly in moisture and nutrient retention.

Cromwell -NZ Nuts Ltd workshop 24th May 2018

Biochar was made from dried willow and eucalypt branches by flame cap pyrolysis in a bath, replicating a trough kiln. The biochar was then crushed manually and broadcast on to plots (1 by 2 metres) having a covering of short grass, midway between the rows of walnut trees, with treatments on each plot being: plot1-biochar, plot 2-nothing, plot 3-biochar, plot 4-nothing, plot 5-biochar, plot 6-nothing.


Application rate was 4.0 l/m2 which using an estimated bulk density of 0.25 equates to 10 t/ha.


WRC Healthy Rivers/Wai Ora – update

Banner image - Have your say

I’ve been following the Waikato Regional Council process on improving water quality & nutrient management which will lead to changes in how farming is carried out in the region. You can find earlier posts on this under the “Waikato” tag. You can link to the new round for ‘submissions on submissions’ from the image above.

I did make a submission (Mar17) focused on how Overseer could potentially impact the uptake of innovative solutions such as biochar but I completely failed to make any impact. A search on the 4-volume summary of submissions pulls ‘biochar’ once! Well done John Allen who was the only success.

It seems that the nascent biochar industry will need to gather much more momentum before anyone will take any notice. Pastoral agriculture is probably the hardest nut to crack due to broad-acre supply and cost issues so maybe we should focus on some sweet spots: animal bedding; AD; feed supplements; nutrient carriers; seed coatings; CHAB, …

So where to from here? If we had a functioning organisation, we could put together stronger submissions to these opportunities for marketing biochar potential and educating RC’s and industry.

Biochar Network NZ(?) – update on progress

The email below has been shared with 13 folk who have expressed interest in participating in an interim committee, to help establish a NZ biochar organisation.

This process was previously notified on 22 July by email to all NZ members of ABE (160 No.) and some other folk with a potential interest in biochar in NZ. This document was attached to the email.

​​———- Forwarded message ———
From: Dennis Enright <>
Date: Thu, 23 Aug 2018 at 17:20
Subject: National Biochar Organisation


Thanks to you all for taking part in developing a national organisation and strategy to support and promote biochar production and use in NZ.

I propose that we can conduct a lot of the work via email and google shared documents initially and at some point we will get together on skype/zoom.
to make this process viable I think that it will be important for everyone to express agreement/disagreement to proposals and/or add your own suggestions.
To begin, Trevor and I have made some proposals for your consideration:
1) We propose that this group prepare a recommendation for the governance and strategy of a national biochar organisation. This recommendation will be circulated widely to stakeholders for their input, with the intention to subsequently ratify it at a general meeting.
2) We propose that we develop a statement defining the purpose of the organisation.
3) We propose that we call the organisation Biochar Network New Zealand
4) I propose that the organisation be an incorporated Society – based on the fact that organisations such as HortNZ and BANZ are both incorporated societies
see following links: 
5)  I propose that a subcommittee of this group draft a constitution or set of rules based on the template provided by nz companies website and other similar constitutions/rules such as the examples given and present to this group for discussion. These rules will be required irrespective of the type of organisation that we decide upon.
6) Trevor proposes that we draft a set of priorities for the organisation.
7) We propose that we establish some dates to complete key steps.
Trevor has shared a google docs file with our details, please check that your info is in there, thanks.

NZ case study on ‘4 per 1000’ report

Dr Carolyn Hedley from Landcare Research has contributed to the above report, dated April 2017. We did not hear much from the past government on their (any) commitment to 4per1000. I’m keen to find out more on where NZ is going with this commitment. Which branch of govt is dealing with this?

When you search the full report, biochar is only mentioned by NZ, China and USA, but still not a major focus. I think new information now being reported can change this.

Soil carbon 4 per mille

2.1. New Zealand

“The estimated mean SOC stocks in New Zealand are 98.7 t C ha−1 to a depth of 0.3 m (Fig. 3). To meet the 0.4% initiative, New Zealand will require a SOC sequestration rate of approximately 0.4 t C ha−1 year−1. The New Zealand Ministry for the Environment (MfE) established the Soil Carbon Monitoring System (Soil CMS) for annual reporting on the land use, land-use change, and forestry (LULUCF) sector in the national greenhouse gas inventory, submitted to the United Nations Framework Convention on Climate Change (UNFCCC). This system provides evidence for larger SOC stocks in long-term pastoral soils compared with established forest land (New Zealand Ministry for the Environment, 2015). Therefore, land use change from forest to pasture sequesters soil carbon over a period of decades. However, there are limited opportunities to convert more forest land to pasture, and this conversion would need to account for the loss of biomass C, making this option less favorable.

Current challenges are to maintain or enhance already high levels of SOC stocks in New Zealand’s productive grazed pastoral soils, as well as find other practical ways to sequester C into soil. The peaty soils associated with our vegetated wetland areas have the largest SOC stock at an estimated 136.06 t C ha−1. However, when drained for productive use they rapidly lose SOC through oxidation of the organic matter, estimated at a rate of 2.94 t C ha−1 year−1 (Campbell et al., 2015). Thus establishing or restoring wetlands can contribute to SOC accumulation. These wetlands could be established in areas otherwise unsuitable for productive agriculture, e.g. high country and floodable areas.

Work undertaken to assess erosion impacts on SOC for LULUCF reporting found that landslides cause a significant net decline in soil C stocks, with eroded sites only recovering to 70–80% of original levels. However, rates of soil carbon accumulation in recent erosion scars have been measured at 1–3 t C ha−1 year−1 for the first 10 years, and 0.4–1.1 t C ha−1 year−1 over a 70-year period (Lambert et al., 1984; De Rose, 2013; Basher et al., 2011). These studies provide useful data on potential rates of SOC sequestration when degraded land rehabilitates to pastoral land use.

SOC stock-change trajectories in long-term managed grasslands have been investigated by resampling some flat pastoral sites previously sampled about 30 years earlier, and the study reported small SOC stock losses at these selected sites (n = 125; Table 1). However, a study by Parfitt et al. (2014), using a different subset of flat pastoral sites as part of a regional soil quality monitoring program, reported increasing SOC, with change rates between 0.32 ± 0.19 t C ha−1 year−1 and 0.57±0.31 t C ha−1 year−1, for dairy and dry stock flat land respectively (n=139). Both researchers observed increasing SOC stock at a small number of stable positions in the hill country (n=19–23); with possible reasons given being: reduced overgrazing, and/or a gradual longterm recovery of soil organic matter following erosion when forests were originally cleared.

Parfitt et al. (2014) linked changes in SOC to soil pH and P fertility, finding the sites they resampled that had decreased in pH had significant gains in C,whereas sites that had increased in pH had no significant gains in C,with possible reasons being that high pH (due to liming) and increased P fertility indicate more intensive management, thereby reducing SOC. Alternatively, there could be enhanced relocation of dissolved organic carbon to greater depths in soils of lower pH.

  • Percival et al. (2000) showed a positive relationship of SOC content to pyrophosphate-extractable Al, Fe oxide, allophane and clay content in New Zealand soils. Current research topics ( on ways to sequester C include:
    • assessing the gap between current and potential levels of carbon storage in New Zealand soils
    • assessing the effect of the more frequent renovation of dairy pastures, and mixed sward compositions.
    assessing the effect of biochar additions to soils, including the economics of incentives for land managers to apply biochar to land.

In conclusion, SOC in New Zealand soils is naturally high. Opportunities to sequester SOC include the creation or re-establishment of wetlands, and land use change (taking into account any impacts on biomass C). Current knowledge suggests that ways to sequester SOC will include targeting specific soil classes (e.g. allophanic soils), and/or specific landscape positions (e.g.wetlands) and using appropriate management strategies.

Efforts by landowners to sequester carbon into soil will need to be supported by improved ways of monitoring change, and New Zealand will need to develop a purpose-built sampling and monitoring protocol to address this challenge.”

For more on the 4per1000 initiative:

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).