Rather than focusing on conventional small plot trial work, the three-year collaborative project between the Foundation for Arable Research (FAR) and Canterbury oilseed producer Pure Oil NZ trialled different management factors on about eight to 10 South Canterbury farms each year.
The Monitor Farm Study looked at all aspects of oilseed rape crop production with the aim of identifying key drivers of yield and profitability, establishing best agronomic practice and identifying areas for further research.
Known for its distinctive bright yellow flowers in spring, oilseed rape is processed by Pure Oil NZ in Canterbury into high quality culinary oil.
Pure Oil NZ agronomy manager Keith Gundry says the collaborative study helped to build greater grower engagement, with growers undertaking on-farm trialling, with input from Pure Oil and FAR.
Key findings, particularly around nitrogen use, are being made as a result of the multi-farm agronomy project.
Over the course of the study, average nitrogen (N) use has dropped from 200 kg in the first year and 195 kg last year to 165 kg for the 2023 harvest. At the same time, average yields have increased from 4.56 tonnes/ha in 2021 to 5.1 t/ ha in 2023 (see graphs).
This lines up with overseas data which shows that for applications above 180 to 200 kg of N/ ha, growers are not getting any further yield response from extra N applied.
The use of nitrogen, in the form of either sulphate of ammonia or urea in early spring, plus applications of plant growth regulators, is critical in setting up a high yielding crop. The aim is to keep the plants healthy and vegetative as long as possible to establish a good canopy, as well as delaying the risk of frost damage in early flowering. “If we can get N into the plant in a timely manner, it stops it going reproductive until the timing is better.”
Canopy management is also key, with a target of 3.5 to 4 Green Area Index at the start of flowering to maximise canopy for yield.
“Canopies that are overly large at the start of flowering result in too many flowers reflecting light which results in low seed set and poor seed fill. It also increases lodging risk,” Keith says.
The project showed that as well as N applications and spring canopy management, other key factors are soil compaction and fungicide programme and timing.
“It’s also given us the ability to dismiss other management factors such as plant population and time in ground as major contributions to yield.”
As part of setting up the study, Pure Oil organised and FAR funded the upgrade of a research weigh wagon to more accurately take harvest yield results from the different monitor farms.
Fairlie mixed cropping farmer Ashley Biggs, who participated in the monitor farm project, says the farm-scale trials have been fantastic. “It has got growers sharing ideas. Everybody has been quite open about what they are doing on farm agronomy-wise. I think it is creating a lot of solutions.”
Farmers have trialled different input timings and amounts. “We are getting a better understanding when it is a whole paddock being trialled, harvested, and yield mapped.”
Last year, reduced rates of N were trialled on farm. “Normally we apply sulphate of ammonia and two following applications of urea. Last year, we applied sulphate of ammonia at the normal timing, but only one of the urea applications, timing this between the previous two.”
This reduced rates by 33 units of N.
Despite this, average yields increased, although this was possibly weather related. “We grew less bulk in the crop and it has got us wondering if we have been putting on too much N too early and growing too much biomass.”
Applying more fungicide has also been of benefit. “As we have been growing oilseed rape for more than 10 years we could be getting a build up of soil borne diseases.”
Biggs Agriculture farm 1800ha, growing 300ha of oilseed rape each year. The bulk of the arable area is in wheat – milling, biscuit, and feed wheat – as well as autumn barley. About 900 head of beef cattle are also finished. The property is largely dryland, apart from 180ha irrigated from Opuha Water.
While oilseed rape is their biggest break crop, they also grow linseed and Asian brassicas and are trialling soybeans. They previously grew big areas of peas but the results were too variable.
“Especially for our broadacre area, all the other break crops such as Asian brassicas and higher value crops don’t have big areas available for contract. For simplicity, having one big area in one crop does streamline things for us.”
Oilseed rape is also harvested early, in January, before wheat, and sets paddocks up for first year wheat, Ashley says.
FAR research leader productivity and value Richard Chynoweth says the monitor farm method offers a fantastic way to identify key production benchmarks across different areas and seasons within the South Canterbury region.
The reinstatement of a weigh wagon located in South Canterbury has allowed the collection of measured yield data from grower managed paddock strips. This data, combined with in-season observations, is helping to define the direction where more detailed research is required, for example, current N and fertiliser applications rates appear adequate and are not limiting seed yield.
A 2022-23 season disease survey has shown Alternaria is the most widespread disease and with the help of location and management diaries, additional management options can now be investigated. These surveys and observations can help direct where FAR should invest in research and development for specific crops, Richard says.
Pure Oil managing director Nick Murney says the success of the programme can be measured by the results with yields and crop inputs. “We are looking for more collaboration with FAR on sunflower and soybeans for the future. It’s also a great way to increase the technical skill of our young Pure Oil NZ agronomists who are working closely with the FAR technical team.”
Pure Oil have employed a new agronomist in Southland, Paige Morton, to support a growing area of oilseed rape and sunflower crops in Southland and Otago. With Paige’s appointment, the aim is to extend the programme to growers in Southland and Otago.
Pure Oil has more than 80 grower suppliers that grow high oleic oilseeds for cold pressing at its factory in Rolleston, near Christchurch. As well as supplying oil in bulk to food manufacturers, Pure Oil has created its own brands in the domestic market for both oil and stock-feed. The Good Oil is the company’s brand for cold-pressed rapeseed and sunflower extra virgin high oleic oils, sold in supermarkets across the country.
Since starting in 2012, production has more than tripled from 5000 to 6000 tonnes of seed, up to 18,000 tonnes now, with oil production reaching eight million litres.
Those figures are expected to continue to climb, with the former biofuel plant not needing any further investment in crushing and drying equipment until it reaches its capacity of around 25,000t.
A shortfall in global sunflower oil, as a result of the Ukraine war, has led to a lift in demand for its high oleic sunflower oil, and planting areas. Globally, 60 per cent of sunflowers grown for oil have traditionally come from Ukraine and Russia.
Pure Oil has also started growing and processing soybeans, a legume with a good fit in the arable rotation.
WORDS SUPPLIED BY HEATHER CHALMERS, FOUNDATION FOR ARABLE RESEARCH. IMAGES SUPPLIED BY PURE OIL NZ.