Canola is a specific type of rapeseed plant associated with high quality oil and meal. The oil is low in saturated fat than any other vegetable oil, and is the best source of omega-3 fats. It is high yielding with oil content of 42-46%. The co-product (meal) is high in protein (48%) and very useful in livestock feed formulation. Canola oil can also be used for manufacturing biodiesel.
The plants are known to control root disease during decomposition of root residues hence it can be used in various cropping systems such as relay cropping, intercrops, cover crops, rotational crops and trap crops.
Canola farming in Kenya it is grown in large scale in Mau Narok, Timau, Endebess, Njoro and parts of central Kenya.
Marketing
Canola can either be sold to processors or growers can set up light industries locally for processing the oil. Market for the oil is readily available due to its high quality. The by-product can also sold as a livestock feed.
Economic Importance in Kenya
Canola has huge potential as an income generator in the country as an oil crop and livestock feed. The demand for vegetable oils low in saturated fats is high hence market is readily available for canola. The by product (cake) is also sold as a livestock feed to livestock farmers. Once established it does not require much attention other than spraying for pest control when necessary.
Ecological Requirements
Altitude: Rapeseed best grows between agro-ecological zones 1800 – 2400m above sea level.
Rainfall: The crop is primarily grown under rain-fed conditions however it responds well to supplemental irrigation. Canola consumes up to 500 mm of water during a growing season and will use as much as 7.5mm per day during peak periods.
Temperature: Canola requires cool weather conditions. The optimum temperature for growth and production is 21 °C. Temperatures below 10 °C result in poor germination and emergence.
Soils: Rapeseed performs well on a variety of soils with the loamy soils giving best results. It does not tolerate water logging.
Varieties: High yielding Canola lines suitable for various agro ecological zones developed by KARLO Njoro include:
Topaz, Gulliver, Niklas, Karat, 81-53413K, Oro, 81-55705B, willi, Christa
Line, Tower, Altex, Mary, Wesroona. These varieties have high oil and protein content.
Planning for production
- Ensure that the production area meet the required conditions
- Select variety suitable for the production zone
- Plan for production inputs such as seeds, fertilizer and pesticides
- Plan for marketing or processing locally.
Propagation: Canola is grown from seed
Land Preparation
Land should be prepared to a fine tilth. Early ploughing in the season followed by two harrows before sowing makes a better seedbed. A smooth, firm seedbed helps to maintain a uniform seeding depth and even emergence.
Planting
The most common planting methods are broadcast and drilling.
- The broadcast method can save time and reduce machinery requirements but stand reliability is sometimes reduced using this method. Seed are broadcasted followed by harrowing of the field to spread the seed. Broadcasting is dependent on soil moisture hence requires rainfall immediately after planting.
- Drilling of seed is the most reliable and preferred method. Advantages of drilling include better seed placement, better seed-to-soil contact and the uniformity of crop. Drilling should be done at a depth of 2-3 cm at row spacing of 18-23 cm apart. Recommended seed rate is 10kg/ha, but lower plant density can be used when the seedbed is well prepared and soil moisture is not limiting.
Fertilizer Application
Soil testing to determine the amount of nutrients required is important. Rapeseed is a heavy user of nutrients. 100kg/ha of DAP is required at planting. Fertilizer application at sowing is more efficient than top dressing. Side banding the fertilizer below and to the side of seed furrow is recommended. Canola is susceptible to boron and molybdenum deficiencies, especially when Mo deficiencies are accompanied with low soil pH.
Irrigation
Moisture stress during flowering and ripening results in reduced yield. The flowering period and maturity are also shortened. In dry weather one or two supplementary irrigations are required for rapeseed to obtain optimum yields.
Weed Control
In large scale production, Pre- emergent herbicides can be used to control weeds. Once established the crop suppress the weeds.
Harvesting
The pods should be harvested when majority of the seeds are in a firm dough stage. At this stage, the seed moisture content is about 35%. The field appears brownish green at this stage and the majority of the seeds are firm when rolled between the fingers. Proper gauging of the correct time to cut off the pods is critical. Harvesting should not be done when the moisture content is more that 45%. It results in immature seeds, less oil and protein. Less that 20% moisture increases shattering losses.
Rapeseed can also be harvested using adjusted wheat combines.
Winnowing or sieves should be used to remove foreign materials.
Drying
Seed harvested with more than 10% moisture should be dried or kept cool through proper aeration.
Storage
For safe storage, a moisture content of 10% is the recommended. Heat build up may occur in storage. This can lead to spoilage of the grain. A perforated granary floor (free air circulation) helps to prevent seed spoilage
Pests
Flea beetles, Red turnip beetle, Beet webworm, semi loopers, cutworms. These can be controlled using recommended insecticides.
Diseases
Staghead or white rust, Sclerotinia stem rot, Black leg, Brown Girdling Root Rot, Alternaria black spot, White leaf spot and grey stem
Control
Select fields and rotation systems that prevent a build up of pests (insects, diseases and weeds). Allow at least four years between canola crops on the same field. This is particularly important for fields that have been infected with sclerotinia white mold or blackleg.
Use of integrated pest management is effective for control of pests and diseases.
Challenges in production
- Diseases and pest can be a great challenge if not well managed; Canola is a plant in the cabbage family hence it is attacked by the same disease and pest as cabbage.
- Canola can deteriorate very first in storage hence proper management from harvest, drying and storage is very important.
- Currently processing factories a only concentrated in a few production areas