Meeting the challenge of how NZ can reduce its agricultural emissions

The Royal Society of New Zealand, which is featuring its Annual Collection of Reviews on its website, this week is highlighting an article by Professor Hong Di FRSNZ and reviewing the potential of inhibiting ammonia oxidisers to significantly reduce nitrogen leaching and emissions in grazing pastures.

In the review article, ‘Ammonia oxidisers and their inhibition to reduce nitrogen losses in grazed grassland: a review‘, Professors Hong Di and Keith Cameron, from Lincoln University’s Centre for Soil and Environmental Research, discuss evidence from the laboratory, and in the field that demonstrates the efficacy of using nitrification inhibitors on pastures to reduce nitrogen leaching and emissions, as well as the roles played by different ammonia oxidisers.

The post says:

Nitrous oxide is a potent greenhouse gas with a long-term global warming potential 265–298 times that of carbon dioxide. The dominant source of nitrogen leaching and emissions is through animal excrement, with urine making up about 80% of the nitrogen released back into the pasture. About 70-80% of the nitrogen ingested by the animals is returned to the soil.

In New Zealand our dominant land use is pastoral agriculture. Animals graze the land throughout the year and a large chunk of our economy is built upon the agricultural industry. Accordingly, as New Zealand works towards becoming a low-emissions economy by 2050, finding effective ways to mitigate our agricultural emissions is a significant goal for society to work towards.

A single urination from a cow produces a nitrate deposit well beyond what can be utilised by plants. This surplus is prone to leaching after it is converted to nitrates, or lost as nitrous oxide gas. Most of the nitrate in animal urine is urea, which is swiftly converted to ammonia when deposited in the soil.

When the urea in the urine hits the surface of the ground, it becomes ammonium (NH4+) and is adsorbed into negatively charged soil cation surfaces, meaning there is minimal leaching in soils with good cation exchange capacity. However, in the soil the ammonium is oxidised quickly and a process known as nitrification occurs. As nitrate is an anion, it is not retained by the negatively charged soil particles, this means when drainage occurs it is leached out of the soil into groundwater or surface waters and will contribute to water contamination. Nitrous oxide is also produced as a byproduct through the denitrification process that occurs alongside the leaching.

If a nitrification inhibitor (NI) is applied to the soil to inhibit ammonia oxidation (the first step of the nitrification process), this can lower the concentrations of NO3 and nitrous oxide emissions caused by nitrification and denitrification.

Significant advances have been made in understanding the role of different ammonia oxidisers, including ammonia oxidising bacteria (AOB) and ammonia oxidising archaea (AOA). Archaea organisms are a relatively recent addition to our understanding of life on earth, and were discovered in the 1970s.

For well over a century it was believed that the nitrification process was mostly carried out by a bacteria called chemolithoautotrophic ammonia oxidising bacteria (meaning a type of microbe that utilises chemicals from the soil—in this case from ammonia, to make food for themselves).

But the discovery that archaea have the gene (amoA) to produce an important enzyme for oxidising ammonia (ammonia monooxygenase) has suggesed archaea may have more of an important role in nitrification than previously thought.

Populations of archaea carrying the ammonia oxidising gene were found to be much more abundant than the AOB in a range of soils, which suggested the archaea play a greater role in the oxidisation of ammonia than AOB. However, recent research targeting the amoA gene have shown that the abundance and activity of AOA and AOB fluctuate depending on the soil and environmental conditions.

Professor Di and his team conducted a study of intensively grazed New Zealand dairy pastures. They collected evidence that AOB grew significantly in number and activity in response to cattle urine, whereas the AOA did not appear to increase upon coming into contact with the urine.

Di’s research team also found that the AOB was significantly inhibited by applying a nitrate inhibitor called dicyandimide (DCD). In his review article Professor Di suggests that AOB and AOA prefer different soil and nitrogen conditions to grow and thrive in, with AOB playing a dominant role in grazed grassland and AOA in soils which are highly acidic or low in nitrate.

The nitrate inhibitor DCD is not currently in commercial use in New Zealand but has proven to effective in reducing nitrate leaching by 44–77% in a variety of rainfall conditions. DCD is awaiting the establishment of a standard for food by the UN Food and Agriculture association before it can be put into commercial use for New Zealand farmers.

The low toxicity of DCD make it an appealing environmental technology, which also has economic benefits of increasing nitrogen use efficiency and pasture dry matter yield. The review article suggests that future research should be investigated to deepen our understanding of the amoA gene, search for potential new nitrate inhibitors, and further understanding of how pasture responds.

Professor Hong Di is Professor of Soil and Environmental Science at Lincoln University and was made a Fellow of Royal Society Te Apārangi in 2016. His major research areas include nitrous oxide emissions, nitrate leaching and relationships with soil microbial communities in agroecosystems.

The review article ‘Ammonia oxidisers and their inhibition to reduce nitrogen losses in grazed grassland: a review’ has been published in Ngā Kete and is available free-to-access for a limited time at Taylor and Francis Online.

Source: Royal Society of New Zealand




Ministers’ Letter of Expectations to the EPA for 2018/19

Environment Minister David Parker and Associate Environment Minister Eugenie Sage have sent the Environmental Protection Authority a formal ‘Letter of Expectations for the 2018/19 Financial Year’

This letter outlines their high-level priorities and operational expectations of the EPA over the year. These expectations will aid the EPA’s Board in its strategic planning.

For more detailed information please read the Letter of Expectations (pdf 1.83MB)

Source: Environmental Protection Authority


Good farming practice plan a step forward for water quality

A plan to help farmers and growers reduce their impact on fresh water, through good farming practices, was launched today.

The Good Farming Practice: Action Plan for Water Quality commits to supporting all farmers and growers to implement good practice principles that will reduce their impact on our freshwater.

The Action Plan, jointly developed by primary sector groups, Regional Councils and the Ministries of Environment and Primary Industries, is a positive step by the primary sector towards improving the health of New Zealand’s waterways, Environment Minister David Parker said.

“This initiative sets out practical measures farmers and growers can take, and also commits them to monitoring and reporting on progress,” Mr Parker said.

“It is intended to ensure that all farmers adopt the good practices needed to protect our rivers.”

Agriculture Minister Damien O’Connor said the Good Farming Practice principles in the Action Plan “are not a stretch for many farmers and growers”.

“The difference is that this plan intends to reach those who are not yet using these good farming practices, for whatever reason.

“The aim is that all farmers and growers develop and implement a farm environment plan that identifies the risk areas for water quality on their property and sets out the actions needed to address those risks,” Damien O’Connor said.

Mr Parker said some Regional Councils already required some farmers to have farm environment plans.

“This Action Plan is expected to accelerate the uptake of good farming practices across all catchments, ahead of any regulation. I look forward to regular reports on progress.”

The Action Plan Governance Group responsible for the plan includes representatives of Beef+Lamb NZ, Dairy NZ, Federated Farmers, Horticulture New Zealand, Irrigation New Zealand, Regional Councils and the Ministries for the Environment and Primary Industries.

Source: Ministers of Environment and Agriculture

Budget provides $15m extra for the Sustainable Farming Fund

Budget 2018 includes $15 million of new operating funding over the next four years for the Sustainable Farming Fund to support more inspiring ideas in applied research and extension projects that deliver economic, environmental and social benefits for New Zealand.

In a joint press statement to announce this, Agriculture Minister Damien O’Connor and Climate Change Minister James Shaw say the Government is investing in projects to build sustainability, productivity and resilience across the primary sector as the Government works alongside farmers and rural communities to provide leadership on some of New Zealand’s most pressing issues.

The Sustainable Farming Fund (SFF) encourages unique collaborations among farmers and growers, scientists and researchers, iwi, local government and others who are making a real difference for our rural communities and the wider primary industries, Mr O’Connor says.

“There has been a massive oversubscription to the fund in recent years, meaning good projects aren’t getting a look-in because the previous Government did not provide enough investment for the fund,” he says.

“In the last SFF round, 86 eligible applications were received but only 28 of these could be accepted.”

Mr Shaw says these projects are led by those on the front line and help find ways to optimise the use of the country’s natural resources and protect the environment for future generations.

“We have set an ambitious target for New Zealand to become a net-zero-emissions economy by 2050,” Mr Shaw says.

“A range of forward-looking measures are required to achieve this. Cleaner, smarter farming is central to our plan for sustainable growth.”

Mr O’Connor says the SFF funding boost builds on work the Government has already prioritised.

Last year, he announced the pilot for SFF Tere, which translates to “be quick, swift or fast”.

“Smaller producers are often key innovators, and four SFF Tere projects are already progressing,” Mr O/Connor says.

“I’m looking forward to doing more to help our primary sector increase value and resilience, with a head start on ever-changing consumer tastes.”

The move announced today was included in the Confidence and Supply Agreement between Labour and the Green Party.

Mr Shaw says the Government is committed to partnering with the agricultural sector to achieve shared goals for sustainability, modernisation and profitability.

“This boost to the Sustainable Farming Fund injects fresh energy into projects that explore how to farm less intensively and more in tune with the environment, while retaining profitability.”

Find out more about the Sustainable Farming Fund at


Beef + Lamb NZ aims for carbon neutrality while DairyNZ names climate change ambassadors

A new blueprint to lift the environmental performance of New Zealand’s sheep and beef sector was unveiled yesterday by Beef + Lamb New Zealand (B+LNZ).

The strategy has been developed in partnership with sheep and beef farmers.

It aims to support sheep and beef farmers to manage their properties to improve freshwater, helping them to continue to reduce emissions and provide habitats that support biodiversity and protect native species.

Another aim is to ensure land use is closely matched to soil potential and capability. That will mean soil health, carbon content and productivity will improve while minimising soil erosion and loss to water ways.

At the same time DairyNZ was announcing the names of 15 dairy farmers chosen to serve as Climate Change Ambassadors.

The ambassadors  have immediately taken up the task of working with the rural community to help other farmers understand the challenge of climate change and what options they have to reduce biological emissions on their farms and make environmental improvements that increase economic sustainability while helping to future-proof their farming business.

Identified through DairyNZ’s Dairy Environment Leaders programme, the Climate Change Ambassadors are already involved in a range of initiatives, including improving water quality, reviewing their farm system to reduce its environmental footprint, and working at a grass-roots level with their community to achieve better outcomes for the environment and farming.
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New technology aims to slash dairy effluent and farmers’ use of fresh water

Lincoln University has teamed up with the fertiliser co-operative, Ravensdown, to develop a breakthrough technology that could dramatically improve the dairy sector’s water efficiency and reduce the risks associated with dairy effluent.

The new system, known as ClearTech, was developed from research by Lincoln University Soil Science Professors Keith Cameron and Hong Di. It represents a $1.5 million investment by Ravensdown.

The technology aims to save billions of litres of freshwater a year by making existing effluent storage go further, with farmers able to separate effluent from dairy shed runoff and reuse the water. The leftover waste can then be turned into nutrient fertiliser for paddocks.

Professor Keith Cameron says the ClearTech pilot project was producing 10,000 litres of recyclable water per milking.

“That’s 20,000 litres a day of water saved, which means we don’t have to use freshwater, and it’s 20 thousand less litres of effluent that get produced,” he said.

The pilot project is installed at the Lincoln University Demonstration Farm (LUDF) and undergoing rigorous testing in a real-world environment to give farmers a preview of the technology.

It was unveiled at a LUDF Farm Focus Day on 3 May by Agriculture Minister Damian O’Connor and representatives from Lincoln University and Ravensdown. A group of 350 dairy farmers attended the event.

The system is installed between the dairy shed and effluent pond and works by binding effluent particles together to settle them out from the water.

The effluent circulating in the ClearTech system is automatically monitored and treated and the separation process kills up to 99% of micro-organisms, such as E. coli, while reducing odour.

Professor Hong Di said similar technology was being used for treating drinking water.

“We’ve taken the same principle and applied it to dairy farm effluent.”

The technology will be commercially available later this year, once testing has been completed.

Ravensdown Effluent Technology Manager Jaime Thompson said the project showed exciting potential to transform “green water” so it could be confidently reused as yard wash.

“About a quarter of a dairy shed’s fresh water use is on yard washing, so the potential benefits to New Zealand are enormous.

“ClearTech will look to save 42 billion litres of freshwater a year – the equivalent of 17,000 Olympic-sized swimming pools.”

She said 70 per cent of dairy farmers’ environmental spending was dedicated to effluent management, so ClearTech would help them to save money and meet their compliance obligations.

Professor Cameron also highlighted a positive initial response to the technology from dairy industry stakeholders.

“We’re really encouraged to see their willingness and desire to collaborate as we engage with them in the development of ClearTech,” he said.

Source: Lincoln University

Curtailing nutrient run-off from farms – expert reaction to Minister’s warning

Environment Minister David Parker told TVNZ’s Q&A on Sunday that tough measures to curb nutrient run-off from farms could stall further dairy intensification.

He signalled the imposition of rules which limit how much pollution farmers can put into waterways (as AgScience reported HERE).

Limits on dairy cow numbers in some areas could be among the consequences.

He said there would not be a direct cap on the number of cattle.

He also said “cow numbers have already peaked and are going down, but yet, in some areas, the number of cows per hectare is higher than the environment can sustain”.

The Science Media Centre ( HERE) asked experts to comment on what a future dairying system might look like.
* Robyn Dynes, science impact leader, AgResearch, comments:

“Requirements or targets for reducing nutrient losses on farms are nothing new in many areas of the country, and in our experience, most farmers are already moving in that direction.

“While reducing stock numbers is one approach to reducing nutrient loss, there is no one size fits all. Whatever restrictions are put in place, it is important to recognise that every farm is different and has a different capacity to adapt and change. This is where research plays a crucial role in helping the transition by farmers – including providing better guidance on land use suitability and future technologies, such as in the digital agriculture space.

“Many farmers have already changed their systems to meet current and future targets, but the challenge is to meet those targets and make a profit. There are different approaches that can be taken around more efficient use of farm inputs like fertiliser and water, better targeting source areas of contamination, and use of alternative animal feed like fodder beet and plantain that have been shown to reduce nutrient losses.

“A big driver for farming has always been what is economic, and the environment is now another important driver. But there are others issues to consider around culture and communities and shared responsibility, that we cannot lose sight of. The risk is that if changes are made without all of these issues being considered, we could end up with unforeseen problems down the line.”

* Professor Troy Baisden, Professor and Chair in Lake and Freshwater Sciences, University of Waikato, comments:

“Globally, humans have pushed the Earth’s limits, and nutrients – both nitrogen and phosphorous – are examples where development has shot well beyond the boundaries describing the ‘safe space’ to keep the Earth’s ecosystems functioning to support us. This is particularly true in highly populated areas of the Northern Hemisphere, but the data for New Zealand show that we’re not far behind. In many areas, we’re already reaching a level of impacts that are difficult to reverse. What I find most remarkable about the Minister’s recent comments is the firmness that we’re not going to keep crossing these limits. That’s what’s really important to note here, and I’ll come back to that.

“How we reverse course is another issue, particularly because few nations have. We already have examples, in areas like Taupō and Rotorua, where there’s been real commitment and investment to protect iconic lakes. That’s resulted in action by regional council legislation that has at least held the line and prevented irreversible eutrophication.

“Yet, it’s important to understand that the progress in Taupō, Rotorua and elsewhere is a bit short of what’s required to maintain profitability while reducing stock numbers. And as a result, getting plan changes working in those areas takes years of understanding thinking and compromise. It tends to lead to a feeling of completion only when everyone is equally unhappy.

“To maintain or improve productivity while reducing stocking, we almost certainly need a more forensic set of tools that can convincingly provide the insights farmers need. Those insights can come in the form of ‘gee whiz’ moments, for instance quantifying that there’s a huge loss of nitrate during short periods, on particular soils. And equally importantly, we need to help find ways to manage a farm that prevent that. In the case of phosphorous runoff, which is also really important, we may be closer with ways to trap the sediment. I think we have some promising techniques, but they still need work.

“Coming back to Minister Parker’s comments, they send the signals that may well lead to more rapid development of tools that will really help farmers become more profitable, but with less stock. That signal is needed to accelerate the science, innovation, and discussions that will help us find a path there. That will take time, but management changes under existing farming system could help us move faster than the land-use change to forestry that has dominated progress so far.

“And, it’s important to realise that sending this signal can have much faster effects than the development of new science. For example, Minister Parker’s commentary may go straight to the agricultural property market, and lenders, firmly suggesting a shift in relating land values to profitability, rather than milk solids production. It has largely been the case that land value is correlated with the milk solids production for a number of years, and a shift in the main driver of land value could have immediate effects. Greater milk solids production means more cows, but greater profit allows different thinking, and the kind that will take us on a journey toward both short and long-term solutions.”

Conflict of interest statement: Professor Baisden’s Chair is funded by Bay of Plenty Regional Council and he is a Principal Investigator in Te Pūnaha Matatiti, the Centre of Research Excellence.