With disappointing markets putting particular pressure on winter oilseed rape margins, we take a hard look at key things
With disappointing markets putting particular pressure on winter oilseed rape margins, we take a hard look at key things growers can do to make the very most of their first choice combinable crop break with leading OSR specialists in this, the first article of a three-part series.
“Yield has always been the first key to arable profitability,” stressed Agrii seed technical manager, David Leaper. “And it’s more important than ever with prices putting winter rape profitability on such a knife edge.
“Commercial crop margin calculations for the coming harvest from our consultancy services show that every 0.5t/ha increase in winter OSR yield is likely to drive down production costs by 10/t – considerably more if the improvements can be achieved without additional inputs.”
Even though the crop is so variable in its performance, oilseed rape yield improvement must be the primary focus for everyone today, argues Mr Leaper. Not least because of the many opportunities available to most growers.
First and foremost, he suggests much can be done to raise farm yields at little, or no cost simply by being more selective about where rape is grown, pointing out that anyone broadening their combinable crop rotations has the perfect opportunity to do this.
“Most growers know only too well which fields don’t really suit winter OSR, whether it’s because of soil type, location, rotational position or any number of other factors,” he said. “So, where they are looking to reduce the intensity of the crop in the rotation they ought to be thinking seriously about how frequently they put the crop into these fields, in particular.
“Growing winter barley rather than wheat ahead of oilseed rape will also help. In addition to being a far less favourable bridge for slugs, barley provides valuable extra time for August establishment; something that’s become especially critical where flea beetles are problematic.”
With a difference of 0.65t/ha between the fungicide-treated yields of the 26 varieties on the current East & West Recommended List, Mr Leaper is convinced that better variety choice has a major part to play in improving OSR performance. However, he is adamant that the greatest gains in variety selection will come from looking well beyond yield – or even gross output – to several key yield-preserving and enhancing characteristics.
Most important in his view are establishment ability, speed of early crop development and foliar disease resistance; especially so in matching varieties carefully to individual farm and field circumstances.
“Establishment is everything in getting the most out of winter rape,” he insisted. “Not only does it determine whether you have a worthwhile crop to manage, it sets the plant population you have to work with for the rest of the season. And we know excessive populations can be just as damaging to performance as inadequate ones. So, more than anything else, we need to choose varieties to match establishment conditions.
“Hybrids certainly seem to have the edge in the vigour of their establishment in the large-scale variety trials we run across the country. But our measurements of leaf emergence and green area index show different hybrids, as well as pure lines, vary widely in their speed of development. This can make all the difference to their performance, depending primarily on soil type, seedbed conditions and sowing date.
“For the best results with demanding soils, in less-than-ideal conditions or from late sowing you need a fast or medium-fast developing variety which has sufficient get-up-and-go to grow away from these challenges,” he explained. “Particularly so in the north. This will allow you to sow at relatively low seed rates with confidence to achieve the 20-30 plants/m2 in the spring we know gives the most productive canopies.
“Where you have a combination of fertile ground, good quality seedbeds and early sowing, however, just like wheat, you need a slower developing variety so it doesn’t put on too much lush, thick growth ahead of the winter and leave you with a canopy that’s both difficult and costly to manage.”
Mr Leaper also advises prioritising high levels of resistance to both phoma and light leaf spot in their variety choice given the yield losses they can so easily cause without the most timely and costly spraying. As early drilling puts far more light leaf spot pressure, in particular, on crops, he sees the most robust varietal resistance as especially crucial for this drilling slot.
Regardless of variety, he identifies good seed-to-soil contact, an even depth of sowing and sufficient early moisture as the key essentials for the best establishment, adding that there’s now overwhelming evidence of the value of placing nitrogen or DAP in the seedbed.
“Our research also shows extra returns from employing a root-boosting seed dressing like Take-Off and/or including Nutri-Phite PGA in the autumn or spring spraying programme,” he reported.
“While we still see too much spring nitrogen going on to large canopies, most crops could almost certainly profit from more potash at this stage. Soil indices may be quite adequate, but the crop has a huge K demand for stem elongation and flowering which needs to be met at the time.
“Another possible area for improvement for those with the ability to apply it late, is nitrogen at flowering. We need to be careful here, though, as we see little consistent response to late N wherever sufficient has already been applied for both the canopy and target yield. Equally, any increase in yield could easily be at the expense of oil percentage.”
Finally, he advocates particular care in managing OSR desiccation, noting that each day of seed-filling lost is known to reduce yield by one to two per cent. This means that going in a week too early with glyphosate could leave typical crops half a tonne or more worse off, not to mention any loss of oil or penalties for red seed.
“This is even more important as, at the traditional spray timing for crops grown at relatively high plant populations and bearing most of their yield on the main raceme, more than a third of the pods in well-structured, modern hybrid OSR canopies may be immature,” he pointed out.
“To capture the greatest yield, desiccation needs to be delayed until the bulk of these pods are sufficiently ripe. This can be 7-10 days later than those on the main raceme. Patience, coupled with genetic resistance to pod shatter and/or the use of pod sealants to minimise seed losses from the more mature upper main raceme pods, will clearly be valuable virtues here.”
– Be selective as to where OSR is grown- Growing winter barley ahead of OSR will help- Establishment ability, speed of early crop development and foliar disease resistance are key to yield enhancement- Desiccation timing is vital to maximise final yield