August is the most important month of the oilseed rape year for Bo Jensen and his Agro Alliancen team near Ringe on Funen in central Denmark – both in planting and harvesting. And last year the care and attention they always put into their August OSR management, in particular, was rewarded by victory in the UK’s 2018 Oilseed YEN competition.
At 4.5 t/ha their winning crop of DK Expansion was far from the highest yielding of the 60 field entries. However, it achieved by far the highest percentage of the site’s estimated production potential at 66%; a much greater testament to its management than simple headline yield.
Impressively too, at fully 31ha, it was one of the biggest fields in the competition which allows entries from just 2ha. Nor was it the best performing crop across the 300ha grown annually in the joint venture run between three of the area’s most prominent estates.
“Winter rape is an important break crop for us,” he explained. “We grow it every fifth year as a rule, generally after ryegrass for seed and ahead of either hybrid rye for seed or seed wheat. It fits well in our rotation and with our workloads. Our priority is always on our top-earning seed crops – which also include white clover, tall fescue, spinach and spring malting barley. But the rape has to pay its way. So we do it as well as we can.”
Strong August establishment is Agro Alliancen’s foundation for OSR success to ensure the robust, well-rooted, eight-leaved plants essential before what can be very cold winters. At the same time, though, it is vital to keep the growing point as close to the soil surface as possible to avoid the winter kill that can be disastrous.
“Vigorous, fast-growing and late-maturing hybrids are essential here,” insisted Bo Jensen. “They often don’t stand out in official trials, which tend to be sown too densely and harvested too early. But they always do better for us than pure lines when sown in 30 cm rows at
30-35 seeds/m2 so their growing points don’t get pushed-up by too much plant competition.
“Fast-growing hybrids give us a good two weeks of extra growth before the winter – three with the seedbed nitrogen – which is invaluable. We also find the light leaf spot we’re seeing more of these days is less of an issue with taller varieties as it takes the disease longer to work its way up the plant.
“To make sure we grow the right varieties for our conditions, we rely on our own field-scale trials, picking those that perform best to concentrate on in the following year. Last year, DK Expansion really stood out, so it’s our main variety this season, alongside past favourites, DK Exlibris and DK Exclaim. This year we are looking at 18 different – mainly DEKALB – varieties in strips across a 10ha field; the sort of testing that really shows us their strengths and weaknesses.”
Early weed control is important to the Agro Alliancen team to ensure the least autumn crop competition. Beyond this, though, the standard crop protection programme is limited to a main light leaf spot and growth-regulating treatment at stem extension, with pollen beetle and seed weevil sprays if required. A PGR is only used where it’s essential to avoid excessively tall crops.
Good August management is equally important to secure the oilseed rape harvest. And here, patience is the key ingredient. All the OSR is direct combined without desiccation. Leaving it to ripen naturally means harvesting often doesn’t start until the second week of the month. But this seen as more of an opportunity than a problem.
“Desiccation gave us an earlier harvest in the past,” said Bo. “But natural ripening means we don’t cut short pod fill. We also build much higher oils, averaging 53% last year (48.5% at the UK’s 9% moisture). And combining is much easier.
“DEKALB pod shatter resistance means we have no worries over shedding, even when our crops are run through by some of the estate’s 1000+ fallow deer which can cause havoc in shatter-susceptible varieties. And we always carry hail damage insurance.
“Winter rape tends to be the last crop we harvest, after our priority seed crops and both milling wheat and malting barley. We know it will stand there and put on rather than lose output, so it makes perfect sense to leave it.
“Unlike cereals, the rape will happily combine a day after some fairly heavy rain, so there really is no downside here, either. And we have quite enough time to prepare and drill the following crop of hybrid rye or wheat; after, we’ve got our next crop of rape securely in the ground, of course.”