Moist seedbeds remain key for oilseed rape establishment as high prices encourage growers to return to the crop.
“With oilseed rape, it really depends on autumn sowing conditions,” says Natalie Wood country arable agronomist for nutrient specialists Yara.
“Last year, we saw an increase as the weather was almost ideal for establishment. If we have enough moisture in that August to mid-September drilling window, we’ll see good establishment conditions again.”
Nutrition is a large factor in the successful establishment of oilseed rape. Where possible, Ms Wood suggests the use of seed treatments to increase that initial speed of emergence. Coating the seed ensures that the nutrients in the treatment are concentrated at the source, she says.
“This means as soon as the seed germinates and roots start to develop, nutrients are being taken up.”
Ms Wood recommends a product containing equal amounts of phosphorous and manganese, both crucial for this early growth stage. Phosphorous assists energy transfer and shoot development, providing a crucial supply for the freshly germinated seed.
Manganese plays a role in chlorophyll production, enzyme activation, and carbohydrate metabolism – without it, deficiency will impact photosynthetic efficiency and limit the plant. But how much difference does the right product make?
“A trial in 2020 showed weight increases of roots and shoots by about 20%. That can make a difference between a vulnerable growth stage to one more able to cope if flea beetle migration has occurred.”
To improve establishment and get the crop away quickly, fertiliser should be applied as soon as possible after drilling. NPK is ideal as a starter fertiliser. Potassium also helps root growth and water regulation, which is beneficial if a dry spell hits after drilling.
“It can be tempting to wait until the crop is up and established before applying,” says Natalie. “But that can lead to a self-fulfilling prophecy. If you haven’t set the crop up with its best chance, you can’t expect it to establish very well.”
Yara trials have also shown positive associations between NPKS addition and winter survival: a 38% survival rate for NS grades is far below the 90-100% when applying an NPKS, in part due to potassium acting as an antifreeze to prevent frost damage.
“Looking at trial data, we also saw an increase of 0.21t/ha when placing fertiliser compared to broadcasting,” says Ms Wood. “At current prices, that’s roughly £90/ha.”
Having both P and K in your fertiliser will also increase nitrogen use efficiency (NUE). Over nine different sites, trials reported an average 20% increase in N uptake due to P and K – one site reached 40%, highlighting the importance of P and K for increasing nitrogen uptake.
“We need to try and make sure there are no limiting factors as the crop moves through its growth stages pre-winter,” says Ms Wood. Key micronutrients important for oilseed rape in particular include magnesium, calcium, boron, manganese, and molybdenum.
“If conditions are right, rape can put on a lot of biomass in the autumn, which risks deficiencies.”
Taking care of micronutrients will ensure there are fewer limiting factors and trials show an increase of about 310kg/ha from an application in the autumn and the spring – so micronutrient applications represent a good return on investment.
Looking ahead to 2022, Ms Wood says taking the right steps mean it is possible to give oilseed rape the best start and take advantage of higher prices. For this reason, more people are expected to grow the crop this season.
“If it’s possible and you still have capacity, give your seed the best possible start with a nutritional seed treatment. In addition, at drilling – or as soon as possible afterwards – apply an NPKS fertiliser to ensure key nutrients are not limited.”