News And Reports
Oilseed rape
by John Cresswell, 2 August 2007
Have you noticed the fields of yellow flowers dotted around farms in the spring? The chances are that you have, since nearly 1.5 million acres are grown in the UK every year. This is an area equivalent to 600,000 football pitches.
Each acre produces one to two tonnes of tiny black seeds and in 2006, the UK produced 1.87 million tonnes of seeds. These are harvested in July and August.
Between 1996 and 2006, the oilseed crop area represented between 7% to 12% of total UK crop area (332,000 and 519 000 hectares), peaking in 2005 and slightly declining in 2006.
Contrary to modern belief, the crop is not grown for government subsidy payments. Farmers are neither paid to grow it by the acre, nor are market prices supported by EU intervention buying schemes. The only return that a UK farmer makes from the crop is by selling it in the market place.
To put the crop in a global context, oilseed rape is the source of around 12% of the world’s total production of fats and oils - at just over 15 million tonnes. Soya and palm oil are by the far the most significant products (2). World oilseed production peaked in 1999/2000, and has subsequently fallen back slightly. In 2002/03, the UK produced 4.5% of global rapeseed production (2).
A Global Perspective
World demand for vegetable oils has grown sharply in recent years – by an average of 3.9% for the 10 years to 2003 (3). Extra production to meet this demand has mainly come from increased soya planting in South America - encouraged by the widespread use of genetically modified (GM) varieties - and palm in South East Asia. Palm oil production has increased through the clearance of large areas of land, principally in Malaysia and Indonesia, at the expense of natural forests.
Historically, oilseed rape oil prices were very similar to soya and other types of oil. However, the growing awareness of oilseed as high quality oil, has led to a significant premium for oilseed over the last few years.
www.neoda.org.uk/pages/market_update
Why do farmers grow oilseed rape?
The majority of UK crop growers depend on wheat, barley and oats for their living. These are all part of the Poaceae or grass family, and share many of the same pests and diseases. Growing the same crop (or closely related crops) on the same land year-after-year is known as monoculture, and is generally regarded as bad practice. Therefore, farmers try to introduce plants from a different family at least once into the three-year crop rotation, in order to protect the land from the build-up of pests and diseases. This tends to improve yields and reduces the demand for artificial inputs – particularly pesticides. These crops are known as break crops.
For many years, British farmers depended on crops from the Fabaceae (pulse) family, such as peas and field beans, to provide this role. Unfortunately, the vast growth in the amount of soya bean planting in other parts of the world, and the consequent fall in prices, made pulses less-and-less viable for UK farmers, and they had to look elsewhere for a break crop.
Oilseed rape has made a very satisfactory break crop. It is one of the few edible oilseeds that can be grown in the cool, temperate climate of northern Europe. Being from the Brassica family, it is very different to the wheat, barley and oats cereal crops and shares few of the same pests and diseases. The plant has a deep tap root, which farmers like, as it can break up compacted soil and leave fields in an improved state. Farmers can use much of the same equipment to grow, harvest and store the crop that they already use for cereals, so they do not need to invest in new machinery. In addition, the yields of Poaceae cereal crops typically increase by 35% following oilseed rape than when they follow one another (4).
Is oilseed rape good or bad for the environment?
Oilseed rape supports a wider variety of invertebrates than comparable cereal crops. These invertebrates attract more insect-eaters and provide a valuable protein source for a wide variety of fledgling wild birds, such as linnets (5), buntings and finches (6). Other bird species feed on the oilseed plant itself (both seed and leaf), such as wood pigeons, meadow pipits, yellowhammers, goldfinches and greenfinches (6, 7). Further species, including the sedge warbler, yellow wagtail, skylark and reed bunting, regularly use oilseed rape crops for nesting (7, 8).
Recent work sponsored by DEFRA in collaboration with the British Trust for Ornithology (BTO), suggested that oilseed rape – of all crops commonly grown in the UK – left the most weed seeds on the surface. Not only did oilseed rape leave the highest number of seeds, but the seed types tended to be of the most useful types for feeding wild birds, such as polyganums (9). The same study revealed that oilseed stubble carried the greatest density of birds in the early winter period, no doubt because of the ample feeding opportunities compared to all stubble types.
Although the efficiency of fertiliser use has been improved by plant breeding, oilseed rape poses a higher risk of nitrate leaching due to relatively high levels of residual fertility left behind after harvest. Farmers frequently attempt to overcome this problem by planting a following crop (normally wheat) very soon after the oilseed has been harvested in order to utilise the fertility left behind in the soil.
As farmers aim to minimise costs and prevent damage to their land (i.e. natural environment), they use as few pesticides as they can get away with to protect their crops. As a result, researchers have developed economic spray thresholds for many pests (18) to help UK farmers identify situations in which they could get away without spraying. Ideally, farmers do not want to use any pesticides, but this is not possible if the pests get a hold and destroy the crop. Therefore, long-term surveillance work on the effects of pesticides was commissioned by the Pesticide Safety Directorate (the government agency which exists to ensure the safe use of pesticides both to people and the environment), and these concluded that ‘there were few adverse long-term effects of pesticides on non-target organisms including insects, spiders, earthworms and soil microbes’ (19).
A 2005 Central Science Laboratory study concluded that ‘oilseed rape makes a negligible contribution to UK CO2 emissions’ (8). It went on to state that oilseed, like all healthy and vigorous field crops, can contribute to carbon sequestration. Incorporating all cereal straw in the UK could potentially sequester 0.3 million tonnes of carbon each year.
Therefore, an important point to consider is – given that we want to eat vegetable oil – if we do not use rapeseed, are the alternatives any ‘greener’?
How green are alternatives to oilseed rape oil?
Palm oil is used as an ingredient in one-in-ten supermarket food products from chocolate to bread and crisps. It is an extremely cost-effective raw material for the food processing industry (i.e. cheap food ingredient). Unfortunately, besides having an unhealthy fatty acid profile for the human diet, the massive increase in production has been at the expense of some of the world’s most valuable and sensitive habitats (10).
Some 83% of palm oil production occurs in Indonesia and Malaysia, and has proved devastating for the rain forest, as well as the Asian elephant, Sumatran tiger and orang-utan (1). Burning of the Indonesian rain forest for palm oil releases a staggering 1,400 million tonnes of carbon dioxide into the atmosphere each year, making Indonesia the third largest generator of carbon dioxide globally (1). In addition, the use of palm oil in the UK food manufacturing industry hardly squares with efforts to reduce food miles as the closest significant producer to UK is Nigeria.
Traditional low-input olive oil plantations are relatively benign and have the best effect on the environment in terms of biodiversity and landscape value. However, as the major supermarkets increase their share of the market and demand higher volumes at lower prices, these plantations are becoming increasingly unviable and are giving way to intensive modern plantations.
An EU commission report recently stated that: ‘Inappropriate weed-control and soil-management practices, combined with the inherently high risk of erosion in many olive farming areas, is leading to desertification on a wide-scale in some of the main producing regions, as well as considerable run-off of soils and agro-chemicals into water bodies. The broad picture for the olive sector is of intensified production leading to certain negative effects on the environment’ (14).
Although recently banned, simazine – a chemical associated with ground water residue problems – was being widely used as the herbicide by these plantations. Traditional plantations do not use artificial fertilisers but under intensive olive systems, applications of up to 390 kg per hectare were common. Olive fly is the most prevalent invertebrate pest, and in the past these have been usually dealt with by use of organophosphates such as malathion and dimethoate (14). Intensive productions lead to increased use of these compounds.
Soil erosion is now a particular problem in some areas of olive production. The EU report stated that ‘aggregate losses of topsoil from olive plantations in Andalucía have been estimated at 80 tonnes per hectare per annum, with even higher rates in certain situations. These estimates indicate a totally unsustainable farming system which is resulting in widespread desertification, as defined by the draft National Action Plan Against Desertification (MMA, 1999). On the basis of these estimates, approximately one million hectares of olive plantations in Andalucía are losing as much as 80 million tonnes of soil per year’ (1).
Therefore, if UK oilseed rape production was replaced by an increase in olive oil production, this would have a very damaging effect on these environments.
A large proportion of the global soya crop is from GM varieties, and the recent increases in production have had enormous environmental costs. Reports from Argentina indicate that soya is grown on over 50% of the cropland in many areas. This monoculture production has led to the development of vigorous weeds and a very high usage of herbicides (25). The clearance of natural vegetation in order to grow the crop is equally concerning. Greenpeace estimated that 2.5million hectares of rainforest were cleared in Brazil in 2005 mainly to grow soya (27). There are also suggestions that soya can have adverse effects on human health – by possibly increasing the risk of some types of cancer and by reducing human fertility by affecting sperm motility (26).
So should we be increasing soya oil production or not?
Is oilseed rape oil healthy?
Over the last few years, the debate around dietary fat has changed from a concern for the quantity consumed to an emphasis on the type of fat. In terms of quality, oilseed rape oil has a considerable amount going for it compared to competitor sources. It has high levels of essential fatty acids such as linoleic acid (omega 6) and alpha linolenic acid (omega 3), expressed in a ratio ideal for human health of one to two parts. Source: British Nutrition Foundation.
In fact, soya bean oil is the only other vegetable oil source to provide significant amounts of both fatty acids (12,17). Oilseed rape oil also contains very low levels of saturated fats compared to other plants sources. http://www.neoda.org.uk/pages/origins.html and BNF(20)
The low levels of saturated fats, high level of oleic acid, relatively high level of alpha linolenic acid and favourable alpha linolenic acid to linoleic acid ratio found in oilseed rape oil are consistent with current dietary recommendations. In addition, the substitution of oilseed rape oil for saturated fats in the diet has been found to have a role in lowering plasma cholesterol. There is some evidence that dietary oilseed rape oil has a positive effect in clot formation, with, in turn, implications for cardiovascular disease. It is thought that oilseed rape oil might have an effect in helping to prevent cardiac arrhythmia – significant because this is a frequent cause of death during myocardial infarction (12).
What about Hayfever?
There is no doubt that a significant percentage of people (up to 40%) suffer unpleasant effects from oilseed rape crops during flowering. These symptoms include eye irritation, runny nose, and coughing. Although no great comfort for the sufferer, the vast majority of sufferers are not affected as a result of an allergy (in fact, under 3%). Such effects are usually caused by a straightforward irritation on the respiratory tract and eye.
There is also no doubt that many other plants produce pollen at the same time as oilseed rape, so it is hard to establish exactly how much of this harm is done by oilseed rape crops and how much by other plants. A large-scale, 11-year analysis of hay fever sufferers in 25 medical practices concluded that peak incidence of hay fever occurred at or after week 25 (i.e. well after the majority of the UK oilseed crop has completed flowering). It also revealed that there was no correlation between hay fever incidence and the location of the medical practices in rural or urban areas – suggesting that oilseed pollen is unlikely to be implicated in the majority of cases (23).
Would people suffer less if no oilseed was grown in the UK? Yes, probably, particularly among those living very close to crops. Would they stop suffering altogether? Very unlikely, unless all other pollen producing plants were removed as well.
The good news is that oilseed pollen is heavier and stickier than many types of pollen (16, 21), and does not travel a great distance - 97% of oilseed rape pollen falls to the ground within 1 metre of the parent plant (22).
Despite this, Borderfields farmers do not grow crops for use in Oleifera adjacent to villages to avoid the unpleasant effect that oilseed rape has on some people.
Are many chemicals used to grow oilseed rape and do they get into the oil?
Oilseed rape, being a vigorous and fleshy plant, attracts multiple pests and diseases (e.g. fungal growth). Careful use of sprays keeps them clean and healthy. On average, in 2001 and 2002, UK farmers used exactly two fungicidal sprays on their crops in order to control the diseases (24). Over the same period, 99% of crops were sprayed with a herbicide to control weeds. The presence of weeds is a serious problem because they reduce crop yields and their seeds can adversely affect the taste and keeping qualities of the oil.
The quality of pesticides and herbicides has been considerably improved by scientists over recent years in terms of their effect on the environment. Dimethoate is an insecticide that used be used on crops, and killed nearly all invertebrates including non-target pests. These broad spectrum insecticides have been replaced by new products, such as thiocloprid, which aim to only kill the intended insect target. The use of organo-chlorine and organo-phosphate insecticides has been phased out by UK farmers, and farmers generally seek to reduce chemical use to a munimum, both out of concern for the environment and in order to keep costs down.
Depsite the fact that oilseed rape is home to many insects and diseases, pesticide use is not heavy compared to other crops. The Central Science Laboratroy concluded in a recent report that 'pesticide use in oilseed rape crops is relatively low compared to that of other crops'(8).
The Pesticides Residue Committee is the body tasked with routine surveillance and evaluation of pesticide residues in food for sale in the UK. Cooking oils are currently looked at as part of their rolling program, and were last subject to a report in 2005. Out of 72 samples of oil tested for 59 types of pesticide, residues at any level were only found in eight oil samples. None of these involved oilseed rape. Six of the eight samples with pesticide residue were from olive oil and two from grape seed oil. All were below the Maximum Residue Limits and the committee concluded that 'none of the residues were of concern to human health' (13). While farmers are not scientists, and no experts in these matters, they do keep a close eye on the scientific reports because they, and their families, are most likely to suffer any side effects from the spraying of pesticides.
What about fertilisers?
Oilseed rape is quite a hungry crop. It has a fairly high demand for nutrients, particularly nitrates, as well as phosphate and potassium. A typical UK crop will be given around 200 kg per hectare of nitrogen in the spring, according to the British Survey of Fertisliser Practise (24). Artifical nitrogen is expensive to produce in terms of energy input, but it has a dramatic effect on the vigour of the crop, and hence its ability to sequester greenhouse gasses. So while the production of fertiliser damages the environment, the growing of crops can balance out the equation again. Having said this, the UK use of artifical nitrogen fertilisers has fallen by around 22% since 1983, and phosphate and potassium applications are at their lowest since records began (24). In recent years, the use of sulphur fertilisers has increased because where British crops used to receive their sulphur via industrial pollution, emission controls have dramatically reduced this source.
This article was written in reponse to a long article in the Guardian by Joanne Blythman and John Vidal. Joanne Blythman and John Vidal are superb journalists. They have done much to inform the consumer about the way our food is produced and encourage better environmental practises. However, there were a number of points in their article, that possibly not having spoken to farmers directly, were not quite aware of. Hopefully, this piece sheds new light on some of these areas.
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