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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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Research: Changing irrigation practice can reduce nitrogen leaching

Significant reductions to nitrogen (N) leaching can be achieved by changing irrigation management practices, and new research has demonstrated just how big those benefits can be.

IrrigationA desktop study led by Dr John Bright, Director Research and Development at Aqualinc Research Ltd, and funded by the Fertiliser Association of New Zealand, has shown that it is possible to achieve an average of 27% reduction in N loss.

The research examined data from 12 case study dairy farms in Canterbury. Using computer models, including Overseer, the researchers were able to investigate the effects of different irrigation management rules on pasture production and nitrogen leaching. The researchers experimented with a different approach than the current practice of irrigating if the soil moisture content drops below 50% of its plant available water.

“We looked at lower irrigation trigger points to see if they provided any benefits,” explains John. “This meant the soil was allowed to dry out more than usual. We also looked at different irrigation targets – varying the soil moisture content we aim to achieve through irrigation.

“We looked specifically at targets that left quite a bit of capacity in the soil to store rainfall should it occur shortly after the irrigation finished. We found that filling it up to 80% of the plant available water capacity and leaving 20% for rainfall was probably the best target level from the point of view of reducing the nitrate leaching substantially while avoiding pasture production losses.”

John was “pleasantly surprised” by the results. “Before we started the project we didn’t know what the impact would be on pasture production, but this was not compromised. We were even more surprised by the consequences of changing the trigger level. We found we could use a much lower soil moisture trigger value in spring and in autumn without having any significant effects on pasture production. This was critical as it allowed the soil to dry out more by delaying irrigation and increased its capacity to store rainfall.”

The research team also deliberately tested target levels that did cause a reduction in pasture production to gauge the limits for irrigation triggers and targets. Applying the principles of adjusting trigger levels during the season and using an 80% irrigation target requires the appropriate irrigation system. It is essential to have a system that can be adjusted to relatively small application levels, with a short return period. Centre pivots and solid set sprinkler systems were found to be the most suitable irrigation methods. These could most easily be operated using the irrigation rules developed through the research.

“About 72% of the irrigated area in Canterbury uses methods that could easily implement these irrigation rules. The balance of the area would require a range of capital investments to modify them or to replace them to be able to implement these irrigation rules.”

Other benefits besides reducing nitrogen loss to water include reducing irrigation water use through improved efficiency and making more effective use of rainfall when it occurs.

“You do have to put more effort into monitoring soil moisture and using that information on a daily basis to figure out whether to irrigate or not, and exactly how much to put on. But at the end of the day, many Canterbury farmers are required to make significant reductions in N losses to water in the next few years. For some farmers, it may be possible to achieve some or all of these reductions simply by changing the way they manage their irrigation system.”

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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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6 July 2022

The British Society of Soil Science has published a research article in the Soil Use and Management Journal detailing the latest analysed data from the long-running Winchmore Fertiliser Trial in Canterbury.

The paper was written by Driss Touhami of the Faculty of Agriculture and Life Sciences, Lincoln University. Touhami is also a member of the AgrioBioSciences Program, Mohammed VI Polytechnic University in Ben Guerir, Morocco.

The paper, titled "Effects of long-term phosphorus fertilizer inputs and seasonal conditions on organic soil phosphorus cycling under grazed pasture", was co-authored by Leo Condron Richard McDowell and Ray Moss.  The report can be viewed here.

Read more about the long-running Winchmore trial on the FANZ website here.


25 January 2022

Final-year Lincoln University PhD candidate Kirstin Deuss is the 2021 recipient of the NZ Society of Soil Science/Fertiliser Association of NZ Postgraduate Bursary Award.

The award recognises the efforts and present (or likely) contribution to New Zealand soil science arising from a doctorate study. It carries a $5,000 one-year stipend.

Kirstin holds a BSC in Biomedical Science from Victoria University of Wellington and an MSC in Horticultural Science from the Technical University of Munich, Free University of Bozen (Italy) and the University of Bologna.

Her postgraduate research has seen her lead a long-term field study on soil and catchment hydrology in Southland. The findings will help understand the role mole and tile drains play in Southland’s unique landscape.

“I’m thrilled to have been selected as the recipient of the NZSSS Fertiliser Association Postgraduate Bursary, it is an honour that I will cherish for the rest of my career,” says Kirstin. “I love working with soils and my career objective is to apply my field, research and management skills towards supporting the sustainable management of New Zealand’s soil resources.”

“My PhD has been challenging but also so rewarding, and this award is a real confidence boost as I prepare to start my new career at Manaaki Whenua Landcare Research in February. I wouldn't be where I am without the support of my many great mentors, friends and colleagues, who have given me so much of their time and energy to help turn ideas into reality and put it all into the written word!

 “It's truly been the best experience of my life and I am really looking forward to where it is going to take me.”

 Kirstin was nominated by Peter Almond, Associate Professor, Department of Soil and Physical Sciences at Lincoln University. He described her to the judging panel as a “highly adept scientist capable of complex quantitative analysis of soil-hydrological systems”.

“I think she is a deserving recipient.  The prestige of the award would further her goal of securing a position working professionally in soil science in New Zealand so that she can contribute to environmental sustainability of our primary industries.”

Fertiliser Association chief executive Vera Power described Kirstin’s research as “hugely important”.

“The more we can understand what’s happening in our soils and catchments, the better placed our primary sector will be to improve farm management, all while protecting the environment.”  

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