What do 19th century steam engines and oilseed rape have in common?
Although we think of oilseed rape as a ‘new’ crop, brightening up fields with their yellow show in spring and early summer, it was first recorded in the 14th century and 500 years later was used as a lubricating oil for steam engines.
Oilseed rape production really took off in the UK in the 1970s. Now, nearly a million acres of these startlingly yellow flowers greet us from afar with their pungent smell. It should hardly be a surprise to learn that it is a member of the mustard family.
Its main product is a vegetable oil, widely used in prepared and processed foods, and the seeds are also used for animal feed and biofuel. The oilseed rape industry is valuable to UK agriculture, being worth about £700 million a year. But its environmental benefits are mixed.
One reason we see so much rapeseed oil growing in our fields is because it helps to fertilise the soil by naturally adding nitrogen to it. This helps to improve the yield of the crops that are grown afterwards, such as wheat.
It is known as a ‘break crop’, a crop specially planted to give the cereal crops a ‘break’ from the cycle of weeds, pests and disease that build up in the soil. Other important break crops include potatoes, sugar beet, grasses, peas and beans.
While providing habitats for wildlife, oilseed rape fields might be one reason for diminishing populations of honey bees. With a high pollen yield, rapeseed is particularly attractive to bees, who in turn are one of the crop’s main pollinators. However, experts have warned that the pesticides used on rapeseed crops could be dangerous to the bees. And the pungent smell of the pollen taints the taste of the honey produced.
Oilseed rape can be processed to create ethanol, diesel and other liquid ‘biofuels’. Such fuels are made from the waste of living things like plant stems, wood chippings, straw and animal dung.
Rapeseed now accounts for about 60% of the biodiesel production in Europe. But recent studies have discovered that it produces much more intense greenhouse gas emissions than fossil fuels. Rather than carbon dioxide, rapeseed oil emits nitrous oxide, which is nearly 300 times more powerful as an agent of global warming.