Canola seed weight (TKW) can vary widely by variety and in different seed lots. Where small seed could be 3 g/1000 seeds and heavy, large seed at 7g/1000 seeds. With not changing the intended lbs/ac seeding rate between the varieties or seed lots, the actual seeds put in the ground have been reduced, which affects final plant stand. Targeted final plant stand is recommended to be between 7 to 10 plants/ft2. To find out the TKW, look on your bag of canola, it should be printed on it.
To figure out how to use TKW and Targeted Plant Stand to determine seeding rate you can use this chart below, or use this formula:
FORMULA 1 : 9.6 x Target Plant Stand x TKW = Seeding Rate (lbs/acre)
From here, an adjustment needs to be made for seedling survivability. In any given situation there will be some seeds that do not make plants. In great growing conditions (soil above 5C, firm seedbed and adequate soil moisture), there will be probably 75% survivability, in cold soils either dry or wet, probably only 50%. To adjust, divide the above formula by the expected survival rate:
FORMULA 2 : 9.6 x Target Plant Stand x TKW = Seeding Rate (lbs per acre)/ % Survivability
Example: I want 8 plants/ft2 final stand and my TKW is 4.0. The soil has just only reached 5C, but it looks like cool, wet weather ahead, so I am guessing only 65% of the seeds will make plants
Seeding Rate = (9.6 x 8 x 4.0)/65 = 4.72 lb/ac
If you have questions, give me a call: Anastasia Kubinec, 204-750-2717