3 Danish golden rules for high oilseed rape yields

Nordic folk are famed for their straight talking, so when Farmers Weekly asked Danish growers Michael and Johann Levy what could be done to improve the UK’s lowly yield average of 3.5t/ha, they quickly offered three simple tips.

Spread rotations, use hybrid varieties at lower seed rates and above all, treat oilseed rape like you would your wheat and invest for the best yields.

Their final point might be hard to swallow for some growers, with the oilseed rape price a little over £250/t, but yield is king for the farming brothers.

The Levy family has been farming near Juelsminde, about halfway up the eastern coast of the Jutland peninsula, since 1895 and has built its area of owned and rented land up to 700ha of clay to heavy clay soils.

The farm grows a range of crops, with the rotation including winter wheat, winter barley, spring barley, ryegrass and red fescue for seed, oilseed rape and forage rye.

See also: Danish crops held back by fertiliser restrictions

The array of crops allows the brothers to grow their hybrid oilseed rape crops every six or seven years and Johann says that is crucial when aiming for top yields.

“I have worked in Germany, where they plant oilseed rape every third year. Yields kept falling and they were spraying [pesticides] more and more,” he says.

“As soon as they changed and widened the rotation, yields started to go up. It really is very important,” he adds.

Last year the farm’s oilseed rape crop averaged 5.8t/ha across 80ha and although 5t-plus isn’t uncommon in the UK, the Danes are doing it on a regular basis, despite restrictions on fertiliser and pesticide use.

This autumn the brothers will be planting a crop they hope will trump the world record of 6.31t/ha, held by Kiwi grower Chris Dennison, but Michael believes there is potential to go a long way beyond that.

“Our yield monitor on the combine has touched 8t/ha before, but that can’t be trusted, so we will get the scales out this season,” he adds.

Michael and Johann Levy

Michael and Johann Levy

Establishment matters

The Danish oilseed rape market is dominated by hybrid varieties – with about 98% of the area sown with these types – and the Levy brothers don’t buck the trend.

All of their 120ha is planted with Monsanto variety Explicit, which has been a consistent performer on the farm for a number of seasons and recently joined the northern Recommended List in the UK.

After harvesting and chopping the straw of the previous cereal crop, the ground is cultivated once or twice with a Lemken Thorit, before going in with a 3m Sumo Trio fitted with an air seeder to drill the crop.

“You need loose soil and making a seed-bed helps the crop start better and grow faster,” says Johann.

The golden oilseed rape rule in Denmark is achieving eight true leaves, 8mm root diameter and an 8cm taproot heading into the winter – considered crucial for crop survival and top yields. This requires a cumulative temperature of 500-600C to achieve.

With that in mind, Johann says sowing after 1 September is too late as light intensity drops, making conditions less ideal for rapid growth.

They sow 30 seeds/sq m to achieve a plant population of about 25 plants/sq m. He adds they have never been disappointed when using lower seed rates.

“Oilseed rape plants want to grow like Christmas trees, with big branches right down [to the ground] and I believe lower populations of 10-15 plants would still be good,” says Johann.

Nutritional needs

While both drilling date and seed rate are crucial decisions to make for the optimum establishment and plant population, the brothers also believe an early application of nitrogen, phosphate and potash are crucial for a fast start.

Patience a virtue at harvest

At Kalsboel farm, they have been direct combining oilseed rape since 1988 and Johann Levy believes delaying harvest by a few days is a cheap way of boosting yield.

Johann doesn’t like spraying the crops with a desiccant such as glyphosate ahead of harvest; while his brother Michael says finding the right timing is also tricky.

They instead opt to let the crop senesce naturally, delaying harvest for as long as possible. Growing varieties such as Explicit with pod shatter resistance helps minimise the risk of seed losses.

“It is the wrong view to force the crop, so we delay it for as long as possible and the second week of August is the optimum for us.

“It helps with seed filling and oil content and is a cheap way to higher yields. Go and harvest some wheat first and leave the oilseed rape until later,” says Johann.

Depending on the season, a nitrogen/phosphate/potash application just before or just after seeding gives the crop the kick-start it needs to get plants to the adequate size for winter.

Johann says it has a big effect on the crop and it is something the farm doesn’t try to save on. Soils are tested every five to six years to ensure P and K levels are maintained.

“We know colleagues that look to save on P and K and they lose yield. Potash is particularly import. We also rotationally lime to ensure soils are kept at the correct pH,” he explains.

Nitrogen rules in Denmark are strict, with each farm having a maximum amount of nitrogen it can use, with the ability to take nitrogen from one crop and apply to another that is more deficient or has more potential.

Use of any nitrogen in excess of the assigned total amount can result in heavy fines and it is estimated many crops are receiving about 15-20% below the economic optimum.

“We apply about 200kg/ha of nitrogen, but I’m sure we need to apply 250kg/ha to get the most out of the crop,” says Johann.

Growth regulation

In their second season in the +1t/ha initiative, a scheme run by Monsanto, fertiliser manufacturer Yara and agrochemical company BASF, the Levy brothers have learned one key lesson.

The +1t/ha project started in 2013-14, mirroring the similar 3×3 initiative in the UK and has devised an input programme that aims to push up oilseed rape yields

It is implemented on a number of field-scale plots around Denmark and allows growers to compare it to the standard programme on their own farm.

Last year the +1t/ha programme averaged 0.496t/ha more than the farm standard of the five Danish farms taking part.

The enhanced programme included an extra spring sclerotinia fungicide, added micronutrients and two Caryx (mepiquat + metconazole) specific plant growth regulator applications.

For the brothers, the jury is out on the extra spring fungicide, as they believe you should react to the season’s disease pressure and only spray twice if necessary, but they have used two 0.7 litre/ha applications of Caryx.

“We use it in the spring to produce more branching, but we also use it in the autumn, unless the crop is drilled late,” says Michael.

Johann points out that the autumn application is sometimes critical to ensure the crop remains short for the winter, which can be harsh on the crop.

“We need to keep the growing point as low as possible and in doing so the crop can often look bad, but we are are still confident it will yield well at harvest,” he adds.

Don’t scrimp

Maximising yield by investing in their oilseed rape crop is going to be a continued philosophy for the brothers, despite expensive growing costs and depressed commodity prices.

Johann says it is a profitable crop on their farm and with the pressures of grassweed control, the approval of grassweed killer Kerb (propyzamide) provides a useful chemical tool in the rotation.

“People see it as a break crop, but why not get the top yield out of it? You need to invest to do that,” adds Johann.