Feeding the world’s growing population

New Zealand’s reputation as a quality food producer is growing.

Optimising food production

Over the next 50 years farmers around the world will need to produce more food than has been grown over the past 10,000 years.

Best use from a limited resource

Fertiliser helps farmers produce food efficiently by replenishing the soil. But fertiliser needs to be used responsibly.

Responsible and sustainable nutrient management

The Fertiliser Association invests in research and tools to ensure farm profitability while minimising nutrient losses to the environment.

The Fertiliser Association of New Zealand promotes and encourages responsible and scientifically-based nutrient management.

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Retirement tribute: Professor Mike Hedley

From having an internationally acclaimed research method named after him to running a highly successful research centre, Professor Mike Hedley can look back on his 40-year academic career with a huge sense of achievement.

The Massey University lecturer and researcher, and Director of the Fertiliser and Lime Centre, retired at the end of July 2018.


Early career

Originally from England, Mike travelled to New Zealand in 1975 to do his PhD at Massey. His research focused on the impact of phosphorus runoff from agriculture on water quality. Not only did he acquire letters after his name, he also found a fiancée – Carolyn – who had arrived in New Zealand two years after him to study at Massey.

He whisked her away to Saskatchewan, Canada in 1978 to complete post-doctoral research. This is where he developed the technique he’s most famous for – the Hedley sequential-phosphorus fractionation method. “One of the researchers in the lab after I left decided to name the technique after me,” says Mike. “Now there are something like 6500 articles that refer to it!”

The technique is a way of assessing the availability of phosphate in soils – a method Mike applied to runoff sediments during his New Zealand PhD research and to wheat soils in Canada.

Further post-doctoral research at Oxford University focused on how plants take up phosphorus from soils. This led to his team winning the Institut Mondial du Phosphate (IMPHOS) Agronomy Award in 1983 for research on the mechanisms of phosphate uptake by plants (shared with P.H. Nye and R.E. White).

Joining the Fertilizer and Lime Research Centre

New Zealand lured him back at the end of the day, however. After marrying in England in 1980, Mike and Carolyn returned to Godzone three years later.

Mike joined the newly formed the Fertilizer and Lime Research Centre (FLRC) at Massey, led by his former professor, Keith Syers.

“There was a lot of debate at the time, as there is now, about what the shape of phosphatic fertiliser manufacturing in New Zealand was going to look like,” says Mike. “We joined with East Coast Fertiliser Company and the New Zealand Fertiliser Manufacturer’s Association, and did a lot of work on the partial acidulation of reactive phosphate rock (RPR).”

The process of making superphosphate involves acidulating it with sulphuric acid.

“Fertiliser companies started to experiment with adding reactive phosphate rocks to superphosphate to give fast and slow release phosphate components and increase its phosphorus content to reduce the cost of transport. ‘Longlife’ or ‘Longerlife’ were the names different companies gave to these RPR-superphosphate mixtures. The new FLRC was contracted to find out just exactly what plant-available phosphorus content these fertilisers held.”

Mike says this work built a close association between Massey University and the fertiliser industry.

“Once we’d developed that association, we developed training courses in the 80s for fertiliser companies – including refresher courses on pasture soil fertility and the use of fertiliser. Over time these courses morphed into sustainable nutrient management courses.”

Evolving workshops at FLRC

The FLRC went on to develop workshops on controversial topics such as the use of phosphate rock and sulphur.

“In the early days Massey was seen as an independent place for the different companies to come and debate various issues. Our workshops were so popular that they soon became an annual event, and with the short courses, became a significant part of my and Lance Currie, the FLRC’s Technical Manager’s, work.”

FLRC staff at Massey have developed other courses as demand arises, with an increasing focus on environmental topics such as greenhouse gases, farm and dairy effluent management, soil conservation, and a new course on soil mapping, which is currently in development.

“It’s the way of the future – professionals employed in the industry come back and learn the new skills and capability that they need in this short course environment rather than covering it in their tertiary education to start off with.

“There’s a lot of demand for our nutrient management courses, which are linked to the Nutrient Management Adviser Certification Programme. Certified Nutrient Advisers are in demand to develop farm environment plans.”

Changes in research focus

Mike took over as Director of the FLRC in 1998.

“I can honestly say that the subjects students are researching now haven’t changed that much from when I started. Back in 1973 Professor Keith Syers wrote a paper about the impact of phosphate fertilisers on water quality. We were doing catchment and stream research in the 1970s. We did collaborative work with the DSIR Freshwater Ecology Division based in Taupo.

“The fertiliser industry was holding workshops to address water quality as well. Then the funding disappeared, and there was little emphasis on water quality research for more than 25 years. But with public perception that water quality was changing, pressure has been on government to put more funding into that area. We’ve come full circle.”

Mike observes that the main changes in research have been the development of new sensors and measurement tools, allowing large areas of farms to be monitored, and farm systems simulation modelling. Publicly available software such as Overseer allows farm consultants to gain an understanding of how farm practices can be modified to address nutrient losses from farms.

Several regional councils have adopted Overseer to get an estimate of the amounts of nutrients that are moving from farms to surface and ground waters. “But given that the movement of nitrate in drainage from farms to waterways is still very much a black box in terms of understanding the science. This is an area that needs new investment in science. In particular, we need to improve our understanding of nitrate leaching mitigation processes such as full denitrification of drainage water nitrate to benign nitrogen gas.”

Reflecting on a long-term academic career

Mike is grateful that he has been able to maintain and develop a long career in science.

“Everybody is very aware in the field of science that to keep successful science moving forward you do need a good career structure for fresh young scientists to follow,” he says.

So what will he miss the most? Mike says it will be the ability to put an experiment into place to test an idea. “Seeing a problem and coming up with an idea – that’s what I’ll miss I think.”

People in the fertiliser industry will miss him too. Mike Manning, General Manager Innovation & Strategy from Ravensdown, who has known Mike since the 1980s, commended his ability to gain trust and cooperation from a wide range of people and organisations.

“We have absolutely appreciated and respected Mike for his calm, considered demeanour when dealing with technical and research challenges that arise,” he says. “The research he undertakes is of the highest quality and is thus relied upon as being robust. And his engagements with industry have always had a solutions orientation.”

Retirement plans

Mike isn’t hanging his research hat up just yet though. “There are a couple of research projects I’ve just committed some farmers to in the area of soil carbon, which I’ll work on one day a week. The rest of my focus will be on family.”

All three of Mike’s children have become scientists, including two who work as hydrogeologists in Perth. A trip to visit a new grandson in Perth will be one of Mike’s first ports of call. Back home, Mike also has plans for his small farm.

“I’m the sort of person who can usually develop challenges, whether they are academic or practical. I’ve got plenty of projects on the farm that need doing. My wife Carolyn is an irrigation and soil carbon researcher so she’ll also help satisfy my interest in science through the discussions she brings home.”

Speculating on future of the fertiliser industry

Mike will maintain an interest in fertiliser issues, albeit more from the sidelines.

“I think what we’re going to see over the next few months, once the Government sorts out its policy on greenhouse gas emissions from agriculture – through the Emissions Trading Scheme, carbon tax or whatever – is a change in the focus for farmers in terms of what management practices they have on farms to deal with mitigating nutrient losses and reducing greenhouse gas emissions.

“From what I can see, the main options rely on what I’d call ‘edge of field’ technology, which is wetlands, riparian strips, afforestation, and land use change. But we’ll also see changes in the way that we feed cows and how forages change to reduce the urinary load from dairy cows, which is the main source of nitrous oxide emissions. So we’ll see a lot of work being done over the next few months and years focused on those issues.

“As for land use change – we will see Beef and Lamb processors contracting farmers to grow legumes as amino acid/protein sources for their plant-based ‘synthetic meat patties’.”

A huge thank you

The Fertiliser Association thanks Mike for his enormous contribution and wishes him all the best in his retirement.

The Fertiliser Association of New Zealand and Dairy NZ funded development of the Nutrient Management Adviser Certification Programme (NMACP). This industry-wide certification aims to ensure that advisers have the learning, experience and capability to give sound nutrient advice.

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