In the early summer it’s hard to ignore oilseed rape. Do you love it or hate it? Indifference doesn’t seem to be an option. Is that sea of vivid yellow that stretches to the far horizon a cheerful harbinger of summer, or a garish assault on the eye that spoils the tranquil pastoral landscape? Is the plant’s distinctive aroma a heady perfume or a cloying stink that you’re glad to get away from?
Until the 1970s the sight of extensive yellow crop fields was relatively uncommon, and what you did see was likely to be mustard, related but different. Mustard was, and still is, grown for the table. It was also used, as is rape, as a cover crop to plough in as green manure.
What is rape then, and why do we now see it grown everywhere? Rape is a member of the cabbage family that produces hundreds of three to four inch long narrow pods on each plant. The seeds when ripe look like black mustard seeds and they’re high in oil and protein; an ideal combination if the extracted oil is valuable and the residual meal is suitable for animal feed.
Rape has been cultivated in Europe since the 13th century, and its oil used for cooking, but only sparingly – and for good reason. There was a serious and potentially lethal problem with it.
It contained two unpleasant chemicals that seriously limited its use for human and animal consumption. A compound called glucosinolate gave it a bitter taste that made it unpalatable, and more worryingly, it also contained a substance, erucic acid, which could cause damage to the heart. This presented a dilemma. Here was a crop that could produce vast quantities of oil, with a protein-rich byproduct, but that had major drawbacks. Historically, rapeseed oil was valued as a lubricant for machinery. It still is but the demand from that quarter would be satisfied by a small acreage under cultivation.
What happened to change things? Oilseed rape had the potential to satisfy an increasing demand for polyunsaturated cooking oil and a need for palatable animal feed. It was a resource not to be ignored – so what was the answer?
The toxic chemicals had to be bred out. Research over the last 150 years, primarily in Canada, finally resulted in a strain of rape that’s low in toxic chemicals. Glucosinolate and erucic acid weren’t obliterated completely, but the scientists were satisfied that the levels of both were low enough to be safe. Once this had been achieved, oilseed rape was a crop that was easy to grow, gave good yields of palatable culinary grade oil, and had a high protein byproduct that could be used as animal feed.
When the UK joined the EEC in 1973, lucrative subsidies were available to farmers for growing oilseed rape and the acreage of its cultivation grew at a colossal rate. Vast fields of yellow blanketed the countryside and became the norm.
Is oilseed rape the miracle plant it’s sometimes hailed as? It certainly has a variety of uses that start from the moment it comes into flower. It produces great quantities of nectar that honey bees love. Some say they get high on it; that it’s their equivalent of crack cocaine, even that it transforms normally placid insects into aggressive individuals, but it may just be that the prospect of such a gargantuan feast makes them hyper. Their fondness for rape nectar can work to the advantage of both farmers and beekeepers and sometimes growers contract with local honey producers for pollination of the crop. There is a drawback. The honey made from rape nectar crystallises very readily and will set in the comb if not extracted quickly.
The rape plant has also for many years been the source of an insecticide. Rapeseed oil is used to spray insect pests. The plant’s detractors point to this fact as a clear indication that the oil must be toxic. If it is, this isn’t why. The oil – and any vegetable oil will do the same – suffocates insects by clogging up their breathing apparatus. It doesn’t rely on any specific chemicals. The principle is similar to when you spray your roses with dilute washing up liquid to kill aphids.
There’s been much recent discussion about biofuels, and oilseed rape is the main suggested potential source. How practical is this idea? The amount of setaside land in the UK is roughly equivalent to 650,000 international rugby pitches. If all of this land were put down to rape cultivation how helpful would that be?
The recent fluctuations in fuel prices make it more difficult to assess, but if all setaside land were used to grow rape, and assuming optimal yields, which is a very big assumption, how much biofuel could we expect? Probably about 4% of the UK’s annual diesel requirement is the answer. You also need to take into account the potential problems associated with monoculture – growing one crop on the same land, year on year. So is rapeseed biofuel a worthwhile prospect either environmentally or economically? At present the jury’s out.
Then there’s culinary rapeseed oil. One of the wonder foods of the 21st century? Top chefs rave about it, nutritionists extol its health benefits, and there’s hardly a county in the UK that hasn’t got producers marketing their own version, and the Four Shires are no exception. We’ve all been consuming rapeseed oil for decades – perhaps unwittingly – in the guise of the ubiquitous “vegetable oil”, source unspecified. It’s long been, and still is, a constituent of margarines and spreads, even those labelled “olive”, and it’s usually what’s included in “spreadable” butter. For decades mayonnaise and baked goods have contained rapeseed oil so what’s suddenly so special about it now?
Previously the oil was all extracted on an industrial scale by chemical means or heat treatment. This resulted in an unappetising product that was best hidden in made up foods. Concerns began to be raised about potential toxicity, which resulted in a move towards cold pressing, and now all over the country artisan producers are supplying virgin rapeseed oil. Made this way it is of course much more expensive, but get a few big names on board and that ceases to matter.
Nutritionally rapeseed oil is lower in saturated fats than other vegetable oils, including olive, and higher in the beneficial omega 3 and omega 6 fatty acids, so is potentially heart healthy – assuming that the levels of erucic acid in oil extracted by this method are low enough not to be problematic.
Just as it’s difficult to be indifferent to the golden horizons and pungent aroma that great expanses of oilseed rape bestow on the countryside, there are for and against camps when it comes to the oil. It depends which research you consult or which newspaper you read as to whether it’s considered healthy, delicious, and you’ll never need to eat olive oil again or, it’s toxic, tastes of greasy cabbage and its only useful place is lubricating a chainsaw.
Most of the vast acreage of oilseed rape grown worldwide is genetically modified, which is a concern to some, but the farm producers of virgin oil are generally at pains to point out that their crops are not.
So is the future yellow? Maybe, but it appears that although the bubble may not have burst, it’s shrunk a little. As of March this year the area recently put down to oilseed rape is the lowest since 2009, according to Farmers’ Weekly. Now, after years of apparently unstoppable success, pests and diseases are beginning to kick in, as a cynic might think inevitable. Profitability is being squeezed. In the Eastern Counties a crop that was once thought of as “black gold” has now been downgraded to “problem child”.
The first alterations made to the rapeseed plant were to breed out the bitter-tasting glucosinolate and the toxic erucic acid to make the seed products palatable and edible. It has been tinkered with to make it mature faster, then genetically modified so it doesn’t succumb to herbicides applied to kill weeds, and now the race is on to develop disease resistant varieties, because there are several fungal organisms that live in the soil that can ruin the crop. Spraying with fungicide increases the cost of production.
Bees aren’t the only insects that like rape. The cabbage stem flea beetle is partial to it too, but unfortunately it’s not the nectar it’s after. The rather handsome iridescent black or bronze adults feed on the leaves, whilst the grubs burrow into the main stem of the plant. Pesticides that kill beetles are harmful to bees too.
It’ll be interesting to monitor what happens to rape cultivation over the next few years. Almost certainly it will remain a staple crop, but probably not the potential wonder source of fuel, culinary oil, animal feed, insecticide and lubricating oil that it once seemed set to be.
Love it or hate it, the likelihood is that oilseed rape will continue to be black gold and problem child both at the same time.