NZBRC: new publication

Investigating the Influence of Biochar Particle Size and Depth of Placement on Nitrous Oxide (N2O) Emissions from Simulated Urine Patches

Ainul Faizah Mahmud 1,2,*, Marta Camps-Arbestain 1 and Mike Hedley 1
1 New Zealand Biochar Research Centre, Massey University, Private Bag 11222, Palmerston North 4442,
New Zealand; (M.C.-A.); (M.H.)
2 Department of Land Management, Faculty of Agriculture, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
* Correspondence: or
Received: 30 September 2018; Accepted: 1 November 2018; Published: 7 November 2018 


The use of biochar reduces nitrous oxide (N2O) emissions from soils under specific conditions yet the mechanisms through which interactions occur are not fully understood. The objectives of this glasshouse study were to investigate the effect of (i) biochar particle size, and (ii) the impact of soil inversion—through simulated mouldboard ploughing—on N2O emissions from soils to which cattle urine was applied. Pine biochar (550 C) with two different particle sizes (<2 mm and >4 mm) was mixed either into the top soil layer at the original 0–10 cm depth in the soil column or at 10–20 cm depth by inverting the top soil to simulate ploughing. Nitrous oxide emissions were monitored for every two to three days, up to seven weeks during the summer trial and measurements were repeated during the autumn trial. We found that the use of large particle size biochar in the inverted soil had significant impact on increasing the cumulative N2O emissions in autumn trial, possibly through changes in the water hydraulic conductivity of the soil column and increased water retention at the boundary between soil layers. This study thus highlights the importance of the role of biochar particle size and the method of biochar placement on soil physical properties and the implications of these on N2O emissions.

Biochar expert from Norway visiting NZ

Dr Pia Piroschka Otte is visiting NZ (again) and will be based in Otago University for about one month from 22 November. She has kindly provided a copy of a new research publication which can be shared upon request…


“Biochar is charcoal produced from feedstock under pyrolysis. It has gained interests among researchers in recent years because of its agronomic and environmental benefits. It is considered to increase soil fertility and crop productivity, and biochar might play an important role as a climate mitigation tool that is able to capture carbon in the soil. However, although research has focused on the chemical, biological, and technical aspects of biochar, we seem to be far away from the implementation of a functioning biochar system. One key aspect needed for the actual use of biochar technologies is increased awareness and emphasis on the social and organizational aspects of its implementation. As there are no functional markets for the services and products needed to ‘produce’ a biochar system, political and market devices are needed. This paper contributes to this debate by introducing a socio-technical framework that investigates the implementation of different biochar technologies in Norway. Based on this socio-technical system framework, we discuss necessary components of a sustainable biochar socio-technical system, and we outline variations of this system based on different levels of biochar production scaling.”

ANZBC18 conference proceedings

A 132 page PDF of the conference proceedings can be downloaded from this link.

Executive Summary

“This report contains the presentations from speakers at the Australia and New Zealand Biochar Conference 2018. The ANZBC18 working group report this is the best conference program to date, with a mix of international and national keynote speakers, presenters and poster presenters. It aims to facilitate understanding of what makes a biochar business model viable economically, environmentally and socially. Conference delegates heard a variety of speakers from Genxing Pan who gave an overview of biochar in China to Professor Stephen Joseph, UNSW reporting on ‘Biochar A Report on World Wide Commercialisation, Product Development and recent Research Findings’. Other keynote speakers included:

  • Doug Pow, Powbrook – Productivity gains from biologically active soil initiated through biocharactivated compost in an avocado orchard
  • Professor Nanthi Bolan, Newcastle University – Biochar-nutrient interactions in soil in relation to agricultural production and environmental protection
  • Dr Lukas van Zwieten, NSW DPI – Overview of 2017/18 Biochar Research
  • Peter Burgess & Ian Stanley, Rainbow Bee Eater – An update from Rainbow Bee Eater on the application of their ECHO2 technology by Holla Fresh and Van Schaik’s BioGro in South Australia.
  • Lotta Ek, Stockholm Biochar Project – Waste Management for Climate Positive Energy Production and Indestructible Urban Soils
  • Mike McGuire and Scott Morgan, Governor’s Office of California – The opportunities for Biochar and how do we unlock the value?
  • Jennifer Lauber Patterson, Frontier Impact Group & Everett Hale, Reep Development LLC U.S. – The opportunity to develop renewable fuels, biochar and wood vinegar from waste streams
  • Professor Tim McAllister, Agriculture & Agrifood Canada – Potential applications of Biochar from mouth to manure in ruminant production
  • Dr Annette Cowie, NSW DPI – Opportunities for biochar as a solution to environmental challenges.

This event was designed for growers, farmers, foresters, policy makers, biochar producers, industry professionals and entrepreneurs. Students and interested citizens also benefited from this event and the availability of these proceedings.”

TV1 news report on biochar activity in Otago

Dennis Enright reported on some of the background to this project in the first biochar workshop report in August (here). Its great to see some main-stream media coverage in NZ. Click on the image for a link to short TV1 news report…

“A central Otago winery is pioneering a new waste reduction technology.

The project reuses old vines by breaking them down to a unique form of charcoal, which can be used instead of fertiliser.

These blocks are called biochar, an ancient technology once used by Amazonian Indians to enhance their soil.

Now its been adopted by the wine industry for sustainable wine-growing, acting as a fertiliser while also reducing carbon emissions.

“Some of the areas that we’re adding to have been mined from the gold miners in the late 1800’s, so those soils are pretty bare. If we can add a lot of nutrients into the soil and a lot of moisture into the soil, the vines are going to do better and it’s going to be better for the soil as well,” says James Dicey from Mt Difficulty Wines.

The old vines and other organic waste are burned in a specially made oven for 5 hours, while the temperature and air intake is carefully monitored. This is then cooled down and becomes biochar.

“Once the Biochar’s ready it’s mixed with this compost produced from the vineyards grape waste…then the mixture is spread onto the vines,” says Jess Cartwright from Bannockburn.

Mount Difficulty is leading this technology that’s helping our environment, and has just spent $50,000 on the project.

“We have to lead the way as farmers, we have to show that we are responsible for our environment, that we really do care for our environment,” says Mr Dicey.”

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.