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Current research programme
The current focus of the NZAGRC’s nitrous oxide (N2O) research programme is on measuring the effects pasture plants and pasture plant communities have on nitrous oxide emissions.
This work is closely aligned to the MBIE P21 and Forages for Nitrate Leaching programmes (FRNL). In addition, an investigative project on a technology to locate and treat urine patches was completed in 2015/16.
Learn more about:
Dr Cecile de Klein, AgResearch
Professor Hong Di, Lincoln University
Application of gibberellins to increase productivity and reduce nitrous oxide emissions in grazed grassland: a review of the evidence
David Whitehead, Grant R. Edwards, Assessment of the application of gibberellins to increase productivity and reduce nitrous oxide emissions in grazed grassland, Agriculture, Ecosystems & Environment, Volume 207, 1 September 2015, Pages 40-50, ISSN 0167-8809, https://doi.org/10.1016/j.agee.2015.03.019.
Emissions of nitrous oxide from grassland systems are attributable largely to the use of nitrogen fertilisers and the excreta deposited by grazing animals. There is increasing interest in using gibberellins as a naturally-occurring growth promotant of herbage that could be used to reduce the use of nitrogen fertilisers while leading to similar or greater increases in dry matter. This may provide practical opportunities to reduce nitrogen intake by ruminants and extend the seasonality of herbage growth in spring and autumn while reducing nitrogen losses, resulting in lower rates of nitrogen excretion by grazing animals and reduced nitrous oxide emissions. Our findings from a review of previous studies confirm that gibberellins promote dry matter production, especially when applied in early spring or late summer/early autumn. When gibberellins are applied alone without nitrogen fertiliser, the nitrogen concentration of herbage is reduced and the impacts on forage quality are small and often not significantly different from those for untreated controls. We calculated the consequences of enhanced herbage production on nitrogen excreta returned to the soil as urine by a grazing dairy cow and estimated that one application of gibberellins will result in a relative reduction in nitrous oxide emission per urination event of 18% when compared with emissions from using nitrogen fertiliser. We used the OVERSEER® model and nitrous oxide emissions factors to estimate the impacts of changing herbage dry matter production, foliage nitrogen concentration and timing of one application of gibberellins on annual nitrous oxide emissions for a dairy farm. For one application of gibberellins in late summer and early spring, we estimate reductions in nitrous oxide emissions of 1.6% and 1.3%, respectively, relative to the response for an untreated control. Incorporating the effects of reduced use of nitrogen fertiliser by substituting one split application of fertiliser in late summer or autumn with gibberellins, we estimate reductions on nitrous oxide emissions of between 5 and 6% relative to the response for the untreated control. We conclude that the use of gibberellins with reduced addition of nitrogen fertiliser has the potential to reduce nitrous emissions from grazed grassland. However, acceptance of widespread use of gibberellins will be dependent on cost benefit analysis for farmers.
Keywords: Forage quality; Gibberellins; Grassland production; Grazed grassland; Greenhouse gas mitigation; Nitrous oxide
Potential for forage diet manipulation in New Zealand pasture ecosystems to mitigate ruminant urine derived N2O emissions: a review
Gardiner, C. A., T. J. Clough, et al. (2016). "Potential for forage diet manipulation in New Zealand pasture ecosystems to mitigate ruminant urine derived N2O emissions: a review." New Zealand Journal of Agricultural Research 59(3): 301-317.
ABSTRACTNitrous oxide (N2O) emissions from agricultural soils account for more than 10% of New Zealand?s greenhouse gas emissions. Livestock urine deposition drives N2O losses from these soils. It has been speculated that non-urea nitrogen compounds (UNCs) in ruminant urine could reduce or inhibit urine patch N2O emissions. However, we hypothesise that UNCs will have no effect on N2O emissions due to their potentially rapid degradation by plants and soil microbes. Our review suggests that plant secondary metabolites (PSMs) are more likely to perform a role in reducing N2O emissions since many PSMs have known antimicrobial properties. Aucubin, found in Plantago, and isothiocyanates, found in Brassica, have been shown to inhibit a key step in N2O production. Future studies should explore this promising research gap by evaluating forages for potential inhibitory PSMs, assessing whether PSMs are excreted in urine after consumption, and determine whether excretal PSM concentrations are sufficient to reduce N2O emissions.
Dr Cecile de Klein: Principal Investigator
Cecile is an internationally recognised expert on nitrous oxide emissions from soils. Born and educated in The Netherlands, she came to New Zealand in 1995 following a postdoc in Cambridge, UK. As Principal Investigator of the NZAGRC she co-leads, with Prof HJ Di, the nitrous oxide mitigation research programme.
She also led an international Global Research Alliance project on developing guidelines for measuring N2O emissions using chamber methodologies. Cecile was New Zealand’s representative on the international panel to review the IPCC inventory methodology for estimating N2O emissions. In her role as Chair of the national nitrous oxide research network, NzOnet, she works closely with MPI Policy in coordinating and conducting national programmes on N2O emissions to improve the N2O inventory methodology.
Agricultural nitous oxide is no laughing matter
Release Newsletter - August 2012
Manipulating nitrous oxide
Release Newsletter - February 2012
New centre at Lincoln University gets the measure of greenhouse gas emissions
Release Newsletter - August 2011
New Centre at Lincoln University (1.24MB)
Nitrification inhibitors - a win/win technology
Release Newsletter - December 2010
Nitrification Inhibitors (0.83MB)
Progress with nitrous oxide technologies in New Zealand
At the recent NZ agricultural greenhous gas mitigation conference, Dr Cecile de Klein presented an overview of the latest progress with nitrous oxide technology developments. Read more about her presentation
Report: Desk-top review of GHG components of OVERSEER
Report prepared for the New Zealand Agricultural Greenhouse Gas Research Centre
PhD opportunity: University of Waikato
NOT LONGER AVAILABLE PhD in Greenhouse Gas Emissions from Grazed Pastures
University of Waikato, New Zealand
We have an opening for a PhD candidate to make measurements of nitrous oxide and carbon dioxide fluxes from grazed pastures using eddy covariance and chamber techniques. Our team is currently measuring fluxes of carbon dioxide at four eddy covariance tower sites over grazed pastures. We have recently installed a quantum cascade laser system to measure nitrous oxide fluxes. The successful candidate will initially test whether chamber measurements of nitrous oxide match those of the eddy covariance tower. Our ultimate aim is to identify farm management strategies that decrease nitrous oxide emissions while increasing soil carbon and maintaining pasture production.
Ideally, you will have experience or strong understanding of measurement of greenhouse gases, such as nitrous oxide, and the ability and motivation to learn eddy covariance techniques. A background in Matlab or similar scripting computer language is desired.
This PhD is co-funded for three years by the University of Waikato and the NZ Agricultural Greenhouse Gas Research Centre (NZAGRC). Expressions of Interest must be submitted via the online form by 1 December 2016 at www.waikato.ac.nz/scholarships/application-forms/University-of-Waikato-NZAGRC-Doctoral-Scholarship. If no applicant is appointed the scholarship will remain open until a suitable applicant is found.
You will be part of a motivated team of researchers and students at the University of Waikato with considerable experience in flux measurements. The PhD candidate will be supervised by Drs Louis Schipper, Dave Campbell and Liyin Liang. Our research team can be viewed: www.waiber.com.
NZAGRC welcomes PCE report on agricultural GHG mitigationWednesday, 19 October 2016The Parliamentary Commissioner for the Environment’s report into greenhouse gas emissions from agriculture highlights the need for a suite of mitigation solutions rather than a single silver bullet.
Camilla Gardiner moved to Canterbury from the USA at the end of July 2015. Originally from Seattle, Camilla has had a passion for agriculture since high school. "I spent a term at a farm school in rural Vermont in my third year of high school", Camilla says. "Four months with forty-five other sixteen year olds, spending three hours a day on the farm plus learning about the land-based environmental sciences. I was hooked". This interest in farming led Camilla to UC Berkeley to study Environmental Sciences with honours in Soil Biogeochemistry. It was a mentor at Berkeley that encouraged her to investigate PhD options in New Zealand and provided some key contacts. Fortuitously Dr Tim Clough was looking for a student at the time and the rest is now history.
Camilla's previous research work at Berkeley primarily focused on the use of compost to sequester soil carbon, so the move to focus on nitrous oxide and urine patches has involved a steep learning curve. Her PhD project involves studying nitrogen compounds and plant metabolites in urine and identifying those which might minimise N2O emissions. The project started with a literature review and this has produced a number of interesting leads, particularly from plantain. This review is currently being revised for publication, with an aim to publish by mid-2016.
Preferring to be out in the field, rather than at the lab bench, Camilla is looking forward to her first field trial. She is currently running a lab-scale study, whilst gearing up to a larger on-farm trial. "Planning a big trial is a huge learning experience", she says. "I've previously only worked with established trials". Camilla is surrounded by a wealth of knowledge though. "I'm the youngest member in the team by quite a long way", says Camilla. "There is a lot of expertise around here to tap into!"
Moving to New Zealand has turned out to be everything that Camilla thought it would be, and more. As a keen skier and tramper, Camilla has been out exploring the scenic South Island as much as she can. The relaxed kiwi lifestyle is also growing on her. "Up until now I've lived in busy big cities. I love the laid back approach to life here in New Zealand".
Providing funding to students and early career scientists to increase capability in the agricultural greenhouse gas emissions mitigation research area and boost international collaboration is a key activity for the NZAGRC.
The NZAGRC nitrous oxide team was joined by two new PhD students in 2015 and they are both now well underway with their studies.
Sheree Balvert has been fascinated by farming from a very young age. She was raised on a dairy farm in the Lake Rotorua catchment area and this led her into the study of fresh water ecology for her Honours and Master's degrees. A realisation that research earlier in the farming process may have more of an impact overall led her to a change of direction after completing her study. "Looking at water sometimes felt like being the ambulance at the bottom of the cliff", says Sheree. "The damage had already been done. By moving to research which focussed on on-farm processes, I felt I could be more effective".
About 10 years ago, Sheree took up a technician role at AgResearch's Ruakura campus. Her focus was soil science and nitrogen loss mitigation. Interested in developing her career further, when an NZAGRC PhD project became available in 2015, she decided to resign from her job and move back to study. Sheree feels that she's initially had it easier than some PhD students. "I'm continuing to study in the area that I worked in", she says. "However, I've still had to learn a whole lot more in a very short space of time".
Sheree's PhD project involves studying a diverse range of forages, their influence on the nitrogen cycle and the loss of N from farm systems. She has a particular interest in brassicas. "My goal is that by understanding the effects of different forages, I can provide farmers with another tool to help them to reduce their environmental impact", says Sheree. She has just completed a laboratory study assessing the impacts of selected compounds from brassicas on the soil nitrogen cycle and their potential for reducing nitrogen leaching. The next step is to take the promising compounds forward into a field trial.
Outside of her study, Sheree has a love of getting active in the great NZ outdoors. Whilst she's reluctant to call them "adventure" sports, she is a keen scuba-diver, white water kayaker and snow-boarder. One impact of the move back to student life is that, for the foreseeable future, skiing trips will be confined to the North Island. "New Zealand is a fantastic place to work and play", says Sheree. "I guess that's what keeps me here".
Pasture technology company receives greenhouse gas funding
Pastoral Robotics Ltd, founded by Aucklanders Geoff Bates and Bert Quin, has received a grant from the New Zealand Agricultural Greenhouse Gas Research Council (NZAGRC) to help optimisation and on-farm testing of its full-size ‘Spikey’ prototype. Spikey® is a tow-behind device for dairy farmers to detect and treat fresh cow urine patches, long before they become visible via increased grass growth. “By the time they are visible, it is too late to do anything much about reducing either losses of greenhouse gases such as nitrous oxide, or nitrate leaching”, says Dr Quin.
Geoff Bates said that Spikey® essentially measures soil electrical conductivity to allow detection of fresh urine patches on a daily or every-second-day basis, and simultaneously treat them with the most appropriate spray treatment for the farm’s location and soil type. The first product developed, named ORUN®, is a mix of the urease inhibitor nbot and the growth promotant gibberellic acid. Field tests to date show an average 70% increase in nitrogen (N) recovery from the urine patch. The ORUN® keeps the urea in the urine in that form for a few days, allowing the urea to spread out so that more plants access the N. This results in more grass growth from every urine patch, and lower N losses.
“Calculations indicate that up to 14% more grass can be grown annually” said Quin. “The main environmental benefit to date has been less nitrate in the soil profile. We are now investigating sprays that will minimise nitrous oxide greenhouse gas emissions in as wide a range of conditions as possible
The pair say that unlike most other ways of reducing losses to the environment under investigation, Spikey® is a win-win solution for farmers in that the extra grass growth obtained makes it very cost-effective for farmers to use in its own right. Towing Spikey® over the 3-4 hectares grazed each day would take only 20-30 minutes, they say. “On top of this, it will also be possible to apply fertiliser nitrogen at the same time, so for farmers ‘following the cows’ with fertiliser urea anyway, the increase in time required would be minimal.”
Pastoral Robotics expects to have an 8-meter width ‘Spikey2’ ready for farm trials in late March.
-- View a short video of Spikey® in action https://youtu.be/77DfSfaovhc
KuDos to Jiafa Luo of AgResearch
"Humbled and surprised” is how AgResearch Senior Scientist and NZAGRC Project Leader Dr Jiafa Luo describes his reaction to hearing his name read out as the winner of the Gallagher Agricultural Science Award at this year’s KuDos Hamilton Science Excellence Awards.
He says he didn’t think he would be the winner, as he was up against strong competition from the other finalist, LIC (Livestock Improvement Corporation), in the awards, which are held annually, celebrating Waikato scientists and their world-leading research and innovation. As well as agricultural science, the categories include environmental science, medical science, science educator and lab technician.
Jiafa is a key player in the New Zealand nitrous oxide research space and his work is having impacts both nationally and internationally. For the past 10 years Jiafa has been planning and leading many large-scale research programmes investigating country-specific nitrous oxide emission factors for deposited excreta in grazed pasture systems. His work has included investigations into nitrous oxide emissions from sheep, beef and dairy cow excreta on a range of soil types, land topographies and farming systems throughout New Zealand. Results from his work have directly impacted the NZ GHG inventory calculations, making them significantly more accurate.
Jiafa has also led several research projects investigating N2O emissions from applied nitrogen fertilisers and farm dairy effluents. The data from these projects is the first of this kind in New Zealand and has also been used as scientific evidence to support the country-specific N2O emission factors for nitrogen fertilisers and farm dairy effluent in grazed pasture systems.
Jiafa has led several research programme objectives examining mitigation technologies and practices for reducing N2O emissions from grazed pasture systems. The NZAGRC, GPLER and MPI funded programmes have tested and quantified the economic and environmental benefits from adopting N2O mitigation strategies (such as restricting grazing, nitrification inhibitors, novel plant species, and timing of dairy farm effluent and nitrogen fertiliser application) into New Zealand dairy farming systems. Results have been widely used by the pastoral sector and published in a number of refereed journal and conference papers.
Well done Jiafa!
See Jiafa in action here: https://youtu.be/FUuNppW0bL4
Reducing New Zealand's Agricultural Emissions: Gibberellins
This publication provides an overview of the impact of gibberellins on grazed grasslands and the potential for gibberellins to mitigate farm nitrous oxide emissions.
1430 Cecile de Klein, Principal Scientist (AgResearch)
Cecile provided an overview of the nitrous oxide research being conducted in New Zealand, with a focus on plant and animal interventions.
Cecile reminded the audience that animal urine is by far the largest source of nitrogen in the New Zealand farming system and that there are a number of key intervention points in the nitrogen cycle to target when trying to reduce nitrous oxide.
Nitrate leaching is also a big issue, so any technology or intervention to reduce nitrous oxide emissions needs to be win:win with respect to leaching.
Cecile outlined three options for reducing nitrous oxide:
1) reduce nitrogen excretion;
2) increase nitrogen uptake by plants; and
3) influence the plant effects on soil nitrogen processes.
Starting with number three, New Zealand researchers are investigating the effects of pasture species and cultivars on nitrous oxide emissions. They have shown variability in pot trials and larger field trials are now underway. Researchers are also studying the effects of brassicas on nitrous oxide emissions and effects of diet on animal urine composition.
For number 2, it appears that planting Italian Ryegrass, which continues to grow in the colder months of the year may have some benefits.
When looking at reducing nitrogen excretion per urination, it appears that the quantity of nitrogen applied seems to be more important that the species that it is being applied to.
The knowledge that we already have about "high risk" times for nitrous oxide emissions, urine being deposited under wet weather conditions with high pasture damage, is being incorporated into on-farm decision management tools. These may be helpful to farmers, but they will need to be able to assess the state of their paddocks easily.
With respect to irrigation, it appears that if grazing is delayed until 6 days after irrigation, nitrous oxide emissions can be reduced by ~40%.
Researchers continue to investigate win:win solutions and are working closely across organisations and programmes to achieve this.
1550 Keith Goulding (Rothamsted Research, UK)
Keith provided an international perspective on nitrous oxide and soil carbon research. With respect to N2O, he highlighted work on investigating the genes related to nitrous oxide emissions and noted that there is one clear message for reducing nitrous oxide, avoid excess nitrogen.
The IPCC has recently indicated that biochar may have a part to play in reducing agricultural GHGs and a number of research groups are searching for natural nitrification inhibitors.
Keith indicated that soil carbon needs to be considered carefully. Data were published that could be interpreted to imply that grasslands could continue to sequester carbon indefinitely. However, this has been refuted and there is agreement that for a specific system there is an upper limit for carbon, and he noted the interesting work in New Zealand in this area. t been proven yet, but it appears that the deeper roots also reduce run off significantly and thus could offer multiple benefits.
Keith concluded with a warning that too much emphasis on soil carbon sequestration could risk taking our eyes off more important climate change threats, such as land clearance and wetland drainage. He also stressed that our priorities should be promotion of good land stewardship and integrated solutions that consider the whole system and do not merely “pollution swap”.
Introducing Dr Jha
The NZAGRC would like to take this opportunity to congratulate Dr Neha Jha on recently completing her PhD and thank her for her contribution to date to the NZAGRC's nitrous oxide research programme.
Neha's PhD study involved steep learning curves on a number of different levels. Originally from Bihar in India, before her arrival in NZ she had never seen such big pastures, let alone cows and sheep grazing outside all day and night. Neha has a Master's degree in soil science and microbiology and these studies focused on Indian agriculture, which is much more diverse than the NZ pastoral system. "Dairying is also big in India", states Neha," but it is very different and the key issues that farmers face are not the same".
After completing her Master's degree, Neha was interested in developing her soil and microbiology skills further and sent through a proposal relating to nitrous oxide emissions from soil to Professor Surinder Saggar (LCR/Massey) and Dr Donna Giltrap (LCR). This proposal resulted in the offer of a PhD position at Massey University and involvement in the NZAGRC-funded denitrification research programme.
Neha's PhD focussed on understanding denitrification processes in different types of soils. During her PhD study, Neha spent a significant amount of time out in those rolling NZ pastures collecting soil samples of differing types from different geographical locations, then investigating their chemical and physical properties and the microbial communities present back in the lab. Key findings were that different soils have differing denitrification potentials, primarily due to the microbes present and soil management history. The end goal of this research is to recognise the soil and environmental factors that have potential to enhance the activity of denitrifiers in reducing nitrous oxide to nitrogen gas. This is vital for the development of novel and effective nitrous oxide mitigation technologies.
Dr Jha is currently completing a one-year postdoctoral position at Landcare Research, still working alongside Surinder Saggar. Her interests in soil, microbiology and greenhouse gases remain high and she is keen to continue publishing and working towards becoming a renowned and respected scientist. Her PhD has led to a number of presentations and she currently has two journal articles submitted for publication. Neha has enjoyed her time in NZ so far and, now that she feels she has conquered the kiwi accent and understands the culture, she is keen to remain here for the foreseeable future.
NZAGRC nitrous oxide programme focussing on the bigger picture
It's been said that in order to see the whole picture, you need to step out of the frame. That's the approach that the Principal Investigators of the NZAGRC nitrous oxide (N2O) programme and their team took whilst planning the work out to mid-2017. PIs Dr Cecile de Klein (AgResearch) and Professor Hong Di (Lincoln University) have ensured that the updated NZAGRC N2O research complements and is well coordinated with the broader nitrogen cycle and water quality related work being conducted in NZ.
"When investigating options for reducing N2O emissions, we must remember that any potential mitigation strategy is likely to have other environmental impacts", says Cecile. "Additionally, researchers that are trying to reduce nitrogen leaching, for example, need to ensure that their changes to the system aren't unintentionally increasing GHGs. Ideally, by aligning our research programmes, we can come up with win:win strategies that reduce on-farm GHGs whilst also minimising leaching and improving water quality".
In order to investigate the effect of forage species on N2O emissions, the NZAGRC-funded team is working closely with the "Forages for Reduced Nitrate Leaching" (FRNL) programme. This will allow the effects of a range of forage species on both leaching and emissions to be measured in the same trials.
FRNL is a six year Dairy-NZ led programme being conducted in partnership with AgResearch, Foundation for Arable Research, Landcare Research, Lincoln University and Plant & Food Research. The principal funder is the Ministry of Business, Innovation and Employment with all partners providing co-funding to the programme. The key aim is to reduce nitrate leaching losses by 20 percent by delivering proven, adoptable and profitable pasture and forage crop options. Dairy, arable (crop) and sheep and beef farms are involved in the cross-sector project which is focusing on three areas - alternative pasture species, crops and farm systems.
Experimental work involves investigating agronomically viable feeds that have a lower N content and feeds that have the ability to change the partitioning between urine and dung, and urine composition, such that both leaching and nitrous oxide emissions are reduced. Also, research is being conducted into the presence and role of natural nitrification inhibitors produced by the plants themselves. By sharing results with FRNL and the NZAGRC-PGgRc funded methane feeds programmes, the NZAGRC N2O team can gain a comprehensive insight into the effect of NZ based feeds and forages on N partitioning, and urinary output and composition. The overall goal is to develop feed management options for mitigating N2O emissions from NZ systems, where all major intended and unintended consequences of alternative species are well quantified.
"Working together does occasionally raise challenges, as the different groups all need to be on the same page regarding common approaches and methodologies before trials get underway", says Cecile. "On-farm trials generally need to be conducted at a specific time of year. Miss the right time, and the trial is delayed until the following year. So we don't always have as much time as we'd like to plan. However, overall there are great benefits from a scientific perspective to working collaboratively and we are much more likely to reach our goal of reducing on-farm GHGs".
The search for plant species to reduce nitrous oxide emissions
Could plants be used to reduce nitrification rates in soils and hence reduce nitrate leaching and emissions of nitrous oxide? Results of screening experiments conducted by Dr Saman Bowatte and his team at AgResearch Grasslands campus in Palmerston North suggest that they could. Plus, the variability of nitrification activity detected presents an opportunity to explore alternatives to synthetic inhibitors such as DCD.
The screening experiment measured the potential nitrification rate in soil associated with 126 cultivars of 26 species representing three functional groups used in temperate managed grassland. The team found little difference between the average nitrification values for grasses, legumes and fodder crops, but there was a 71% difference between the lowest and highest nitrification values. Fortuitously, several cases were found where a low nitrification rate was coupled with an above average biomass, suggesting that some currently available cultivars may have lower N emissions - a possibility that is now being tested out in the field.
Over the past New Zealand winter, 18 plant species/cultivars carefully selected from the screening experiment have been quietly growing away in a paddock at Grasslands. The team sowed the experimental plot trial back in mid-April and have been busy weeding, fertilising and watering as required to ensure good growth ready for the next stage of the work. This will involve adding urine to each species/cultivar and then measuring the nitrous oxide emitted.
The hypothesis is that the results seen in the glasshouse experiments will be repeated in the field and that some species will have lower emissions than others. Ideally, the reduction will be of a sufficient magnitude to warrant further investigation and lead on to potential options for low N emitting plant species for use in NZ pastoral settings and beyond.