All About Rapeseed: Liquid Gold

All About Rapeseed: Liquid Gold

A piercing odour and delicate yellow flowers turn the landscape into a golden wonderland. Blooming rapeseed fields truly are a beautiful sight. 

The journey from its domestication to becoming one of the world most important oilseed crops started ca 2000 B.C.E in India. By ca 35 B.C.E, it had made its way to China and Japan. Not too late after that, in 13 C.E European farmers too started cultivating rapeseed and with great success. Compared to other oilseed crops, rapeseed can grow in rather cold temperatures making it a go-to crop for farmers living in the northern hemisphere. However, during the Middle Ages in Europe, the use of the crop was quite limited. Rapeseed, which was grown for its oil, was mainly used for cooking and improved upon light sources. Especially in the early middle ages, candles were generally made out of rendered animal fat. Though the candles served their purpose, they produced a dark smoke and foul smell since they were made out of fat. On the other hand, rapeseed oil produced a bright white light and could illuminate a larger area than tallow candles. However, the most significant benefit may have been that rapeseed oil does not produce dark smoke when burned and spares the consumer of rancid animal smells. Finally, In 17 C.E, the use of rapeseed and its oil expanded into the industrial sector, making it a highly sought after product to this day. 

Between 1698 and 1765, the Steam Engine was invented and improved upon independently by several engineers. As given by its name, a steam engine is dependent on steam to produce power through which a vehicle, e.g. an old locomotive, can move forward. This steam is created by boiling water which is stored in a so-called boiler compartment. Old locomotives, for example, burn coal underneath the boiler to vaporise the water. Once the steam has been created, it travels to the so-called piston engine. Piston engines convert chemical energy into mechanical energy. In the case of a locomotive, the engine moves the wheels by pressuring a driving rod that is connected to the wheels themselves. As the pressure in the motor enters and exits, the rod is moved backwards and forward, turning the wheels. But where does rapeseed some in? Water and oil are known not to mix well and but in the case of rapeseed oil, it had some valuable properties. A motor has many moving parts that need to remain lubricated to property function, precisely what rapeseed oil was used for. Compared to other alternatives at the time, rapeseed oil can coat and adhere to the metal surfaces of the engine parts much longer, even as they got washed by hot steam. A few years after the engine was invented, engineers began incorporating it into other machinery to improve everyday life, specifically within transportation. Locomotives, as exemplified above, were one such use case. Steam-driven boats also became popular both for the transport of goods and people. In 1903 the use of rapeseed oil was taken to a new level and quite literary so. 

The Wright brothers were the first to construct a functioning aeroplane successfully, and a steam engine powered it. As the use cases of rapeseed oil diversified and the general demand for the oil, e.g. for vehicles, increased, so did its cultivation. Today, the world’s biggest cultivator of rapeseed is Canada, with over 19 million metric tons produced between 2019 and 2020. The second-largest producer is China, metric tons who between the same years produced 13 million tonnes. What made Canada the largest cultivator of rapeseed? During World War 2, the production of aeroplanes but also naval ships increased heavily, and all of the motors required rapeseed oil. The leading producer and supplier of the oil were Canada, and they had to rapidly increase their cultivation which before the war was virtually non-existent. 

Cultivation and Harvest

Rapeseed is a member of the mustard family and has, through various breeding programmes, produced many different cultivars with the selected properties such as producing extra high levels of oil. 

The cultivation of rapeseed can begin in both autumn or springtime, with specialised seeds available for both. As mentioned earlier, one reason why rapeseed has gained wide popularity, especially in regions with a colder climate, is its ability to germinate and grow regardless. Rapeseed seeds can germinate in temperatures as low as 5 degrees celsius. Other reports documented crop growth continuing even at 0 degrees celsius. Soil conditions for rapeseed don’t need to be too specific, and the plants grow well even if they are very saline. For optimal growth, the soil should be well-drained and requires between 40-45 cm of water during the entire growing season. 

Once the seeds have been spread, it takes between 4-10 days for sprouting to occur. However, variation between fields and seasons can be expected. Factors such as the depth at which the seeds have been planted, temperature and moisture level all impact the growth speed. During the early stages of the seedlings and young plants, extra care has to be taken as they are more vulnerable to the attacks of diseases and other best such as the flea beetle that likes to snack on the young plants. Flea beetles can also become a problem and feast on the crops later on in the season and are especially destructive during dry and sunny weather. The Diamondback moth larvae is another self-invited dinner guest on rapeseed fields. This moth takes a particular liking to the flowers and pods during the early stages of their development. Another major threat to the harvest of rapeseed is white mould that affects the stem. Infestations generally occur right after flowering, and the weather has become cold and wet. As the petals of the flowers are no longer required, they fall to the ground but bring the spores of the white mould with them. On the way down, petals may brush against the steam and leave spores of the mould behind. An infected stem will have white lesions across it. The mould continues to grow both inside and outside the stem. Ultimately the plant starts withering. So how can farmers minimise crop damage? Canadian farmers, for example, prepare for potential fungus infections by preventatively applying fungicides in spring rapeseed. However, with many pests and diseases, a cautious eye has to be kept on the fields. Precision agriculture can be a big help. Whether farmers want to optimise the application of their outputs or just monitor the health of their plants, precision farming instantly sends all the information to farmers devices of choice. 

After several weeks of growing, a more extensive leaf area index and warmer weather, the buds and flowers of the crops begin to form. Earth rapeseed plant is adorned by many flowers, which each have four petals. After blooming, which lasts between 14-21 days, the flowers turn into a pod containing several tiny black seeds (much like a miniature version of peas). It takes between 35 to 45 days for the pods to fill. At this point, the plants have reached their maxim height with is bout 30 cm above the ground. When between 30-40% of the crops seeds have turned from green to black, and the stem is brown to red, the crop is ready for so-called swathing. Like many other crops, rapeseed needs to achieve a specific moisture level before being harvested. This is important to ensure that the crops can be handled and store without distorting, e.g. by rotting. Swathing is a way to speed up and even the drying crops to achieve the desired moisture level. Swathing is achieved by cutting the crop and dividing them into rows, and leaving them to dry. Once the harvest is completed, the rapeseed seeds can be processed and become many different products, such as frying oil in kitchens worldwide. Rapeseed is approximately 40% oil and has a high protein content of around 23% protein. Due to its high protein content, rapeseed is also widely used as animal feed. 


Frequent questions about rapeseed

Q: Are rapeseed and canola the same plant?

A: Yes! The term canola is mainly used in the United States.


Q: Is canola a vegetable oil?

A: Yes! Vegetable oils is an umbrella term that includes all plant-based oils. Since canola is a plant, it falls under that category. 


Q: Where does the word rapeseed come from?

A: The name rapeseed is derived from the Latin species name it belongs to Brassica rapa. Rapa means turnip.

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