Improving nitrogen use is at the top of growers’ to-do list for raising oilseed rape yields to 5t/ha and beyond, according to a new survey. Louise Impey reports.
Oilseed rape growers are already responding to an increasingly unpredictable climate by refining variety choice and crop management, according to a new survey.
Nearly 60% saw climate as the key obstacle to raising yields to 5t/ha and beyond, particularly the less reliable autumn conditions when establishing crops.
These are the key findings of an exclusive Farmers Weekly survey of 230 farmers, carried out in association with Dekalb.
For more on this: See all of the articles on High 5 OSR yields
However, it’s not just about yield, almost half of the growers that took part said they would be happy to sacrifice 3-5% of potential crop yield when selecting varieties in favour of those that offered greater on-farm consistency.
Furthermore, the highest-rated characteristics in a variety, other than output, were vigorous establishment, performance consistency and standing power – which may aid in the quest for consistency. Each of these were named by more than 60% of respondents.
The average on-farm yield achieved by respondents in the past five years was 3.84t/ha, with 35% opting to grow oilseed rape once every four years in rotations. Just 11% were growing the crop once every two years.
However, in the 2012-13 growing season, average yield was down at 3.48t/ha. That corresponds with the national yield figure of that year, says Simon Kightley, director of crops and agronomy at NIAB TAG, who believes that sub-optimal variety choice had a role to play.
“Weather effects were also evident,” he adds. “Higher yields are associated with certain weather patterns – the crop always does better when there’s a warm October, a cold and dry December and a sunny, warm April.”
Among the respondents, not only were yields down, some 20% of their oilseed rape area was lost last year.
These initial findings are not surprising and show how growers are using variety selection to cope with unpredictable conditions, says Geoff Hall of Dekalb, who points out that the survey was done just after the very difficult year leading up to harvest 2013.
“You have to remember that it had been very wet, with many growers struggling to get crops into the ground in time and others having to abandon their cropping plans. Those crops that did get drilled then faced considerable difficulties with pests and worsening weather, followed by a very late, cold spring.”
Understandably, growers are keen to have varieties that are more likely to withstand whatever the elements may throw at them, he continues.
“Varieties that come out of the ground quickly, remain standing and deliver a consistent level of yield, every year, are the ones which give them peace of mind.”
Of the total area grown last year, 53% was down to hybrid varieties, with conventionals taking the remaining 47%. The hybrids yielded 3.55t/ha on average, with the conventionals coming just behind at 3.39t/ha.
The most popular variety choices were DK Cabernet, which accounted for 20% of the survey area, followed by PR46W21 at 9%, Compass and DK Expower with 8% each and Excalibur at 6%. Others achieving 5% or more included DK Camelot, DK Extrovert and Quartz.
The varieties in the ground this year are very similar – with DK Cabernet again proving to be the most popular at 17% of the area, followed by DK Extrovert, PR46W21, DK Expower and Quartz. The hybrid and conventional split has shifted in favour of hybrids, taking 58% of the area, compared with 42% for conventionals.
There are many establishment systems for oilseed rape, and the survey confirmed the trend away from the plough to lower cost approaches, with only one-fifth of growers preferring to plough land followed by drilling. The dominant approach used was non-plough-based cultivation followed by drilling, with 33% describing it as their main system.
Single-pass subsoiler-mounted seeding was the main method for 22% and single-pass cultivator-mounted seeding for 14%.
“The reality with establishment systems is that many growers need to save time and money, so single-pass approaches are gaining ground,” says Mr Kightley.
While the popularity of wide-row, sub-casting systems is due to their speed and simplicity, growers should not forget about the need for consolidation for good seed-to-soil contact, he adds.
Back in 2010, Farmers Weekly carried out a similar survey in association with Dekalb and results show that the most important characteristics in oilseed rape variety choice have changed in the three years since then. In 2010, growers gave ease of harvesting and disease resistance much higher ratings than they received in 2013.
“This time, vigorous establishment was top, named by 82% of participants,” says Mr Hall. “This reflects their recognition of the importance of getting the crop away quickly, so that it is less vulnerable to pests and adverse weather.”
Following this came performance consistency (66%), standing power (62%), ease of harvesting (57%), disease resistance (55%) and pod shatter resistance (54%).
Likewise, when asked about the importance of oilseed rape traits, those receiving the most agreement were vigorous establishment, rapid autumn development and pod shatter resistance.
Various sources of information are used when it comes to variety choice. When asked, almost one- third (29%) relied on independent agronomists or advisers, with personal growing experience being the next highest at 20%.
The HGCA Recommended List was also mentioned, with 19% of the respondents naming it as a good source of variety information.
Looking ahead at the challenges to increasing yields to 5t/ha, the top one was again climate related with less reliable autumn conditions being named by 59% of respondents. This was followed by the perpetual slug threat and pigeon grazing, both at 51%.
After these came the loss of neonicotinoid seed treatments (36%) and worsening weed problems in the rotation (26%).
“This is another change to the results seen in 2010,” says Mr Hall. “Back then, growers were more concerned about the increasing agrichemical costs and growing disease threats, although autumn conditions were mentioned by over a third.”
Picking out one of the challenges, the survey asked growers about the likely impact of the loss of neonicotinoid seed treatments for their farm businesses in 2014-15. Increased use of pyrethroids was the most frequent response, scoring 83%, while a reduction in yields was named by 54%. Some 36% of respondents expected to increase seed rates.
According to independent researcher Alan Dewar, pyrethroid sprays have to go on early, before damage has occurred. “Used in this way, they will control flea beetle.”
But resistance to pyrethroids has already been reported in Germany in flea beetle, he warns. “Pyrethroids will be a short-term solution, as we can expect resistance to develop and they won’t control aphids carrying turnip yellows virus.”
Finally, when asked about the factors that growers thought could help improve oilseed rape performance and take yields to 5t/ha and above, optimising nitrogen fertiliser inputs was also mentioned by two-thirds of the sample.
This was followed by improving soil structure and organic matter levels (42%) and better use of fungicides/plant growth regulators (39%).
(More on oilseed rape)