Preparing a Combine Harvester for Rapeseed Harvesting

[MikePhua]

Rapeseed and Its Harvesting Challenges
Rapeseed, also known as canola in some regions, is a high-value oilseed crop cultivated extensively across Europe, Canada, and parts of Asia. Its small seed size, high oil content, and tendency to shatter easily make it one of the more technically demanding crops to harvest. Unlike cereals such as wheat or barley, rapeseed requires specialized combine adjustments to minimize losses and ensure clean separation.
Terminology annotation:
- Shatter Loss: The premature release of seeds from pods due to mechanical impact or vibration, often occurring before or during harvest.
- Header: The front attachment of a combine that cuts and gathers the crop.
- Sieves: Adjustable screens inside the combine that separate grain from chaff based on size and airflow.
- Rotor Speed: The rotational speed of the threshing mechanism, which affects separation efficiency and seed damage.
Modifying the Header for Rapeseed
The first step in preparing a combine for rapeseed is modifying the header to prevent seed loss and improve feeding. Standard cereal headers often allow rapeseed pods to fall between the cutter bar and auger, leading to significant shatter loss.
Recommendations:

• Install rapeseed side knives to cut lateral stems cleanly and reduce pod drag
  
• Fit a rapeseed kit or sealing plates to close gaps between the cutter bar and auger
  
• Adjust reel speed and position to gently guide plants into the header without aggressive impact
  
• Use a draper header if available, as it provides smoother crop flow and reduced seed loss
  

In one UK farm, switching to a draper header reduced rapeseed losses by nearly 30%, especially in dry conditions where pods were brittle.
Adjusting Threshing and Separation Settings
Rapeseed requires lower rotor speeds and tighter concave clearance to avoid seed damage and ensure effective threshing. The goal is to separate seeds from pods without crushing them or blowing them out with excessive airflow.
Suggested settings:

• Rotor speed: 450–600 rpm depending on crop moisture
  
• Concave clearance: 3–5 mm for dry seed, slightly wider for damp conditions
  
• Fan speed: 850–950 rpm to balance cleaning and retention
  
• Upper sieve: 6–8 mm
  
• Lower sieve: 3–4 mm
  

Operators should monitor grain tank samples frequently during the first few passes and adjust settings to reduce cracked seeds and unthreshed pods.
Sealing the Combine to Prevent Leakage
Because rapeseed is extremely small—typically 1.5–2.5 mm in diameter—it can escape through even minor gaps in the combine body. Sealing the machine is essential to prevent seed loss and contamination.
Steps to seal the combine:

• Inspect and seal gaps around elevator housings, auger troughs, and grain tank joints
  
• Use foam strips, rubber gaskets, or silicone sealant where appropriate
  
• Check under the rotor and around the cleaning fan for escape paths
  
• Ensure unloading auger joints are tight and free of wear
  

One operator discovered that a missing bolt on the clean grain elevator allowed several kilograms of seed to escape per hour. A simple patch eliminated the issue entirely.
Monitoring Moisture and Timing the Harvest
Rapeseed should be harvested at 8–12% moisture for optimal storage and oil extraction. Harvesting too early increases drying costs and seed damage, while waiting too long risks shatter loss and weather damage.
Best practices:

• Use a moisture meter to test seed samples from multiple field zones
  
• Begin harvest when average moisture drops below 12% and pods are fully mature
  
• Avoid harvesting during midday heat to reduce pod brittleness
  
• Store harvested seed in aerated bins and monitor temperature regularly
  

In Germany, a cooperative reported that harvesting rapeseed between 9 a.m. and noon reduced shatter loss by 15% compared to late afternoon operations.
Conclusion
Preparing a combine for rapeseed involves more than just mechanical adjustments—it requires a strategic approach to header configuration, threshing settings, sealing, and timing. With careful preparation and attention to detail, operators can minimize losses, preserve seed quality, and maximize profitability. As rapeseed continues to grow in global importance for biofuel and food oil production, mastering its harvest becomes a vital skill for modern agriculture.