Canola growers can take some steps at swathing time to minimize green seed and maximize the quality of the harvested crop, according to the Canola Council of Canada (CCC).
The first line of defense is to avoid swathing canola when temperatures are high (upper 20’s to 30 or more), especially if crops are at less than the optimal 60% seed colour change and there are accompanying winds, advises CCC senior agronomy specialist Jim Bessel. “The rapid dry-down of the plant material will not allow for proper curing which could lead to situations with elevated green seed.”
Once swathing begins, producers should consider some factors in determining dry down time, says Bessel “The larger the swather width the greater the volume of canola in the swath and the more time it will take for that biomass to dry down. Larger swaths may need to be left out longer to allow for sufficient curing.”
Most often the weight of a dense swath will settle into the standing stubble and anchor itself, requiring minimal pressure from a swath roller. “The goal of using the swath roller should just be to smooth out the swath and nicely tuck the outside edges into the standing stubble, thereby anchoring the swath against possible wind damage,” says Bessel.
While anchoring the crop reduces wind damage, Bessel points out that pushing down the swath by using a swath roller should be done carefully. Excessive compaction can be a concern when swath rolling, as a large dense mass of material may limit air infiltration, slowing the dry down process and/or increasing curing time. This could also increase the risk of seeds sprouting due to slower dry down following wet weather. “However, for low plant population stands or short crops, producers may have no choice but to push the swath on the ground to sufficiently anchor the crop. As a result, drying and curing time could potentially be delayed. ”
Air movement, sun light and moisture movement are all factors to consider when assessing the size and density of the swath. “Typically, you will need to leave the windrows in the field at least two or more weeks for sufficient curing.,” says Bessel. “It may take longer because of the large amount of green biomass, and will also depend on the seed colour change at swathing time and weather conditions.”
Bessel suggests that prior to combining, producers take the time to check for maturity of the seed, and whether the swath cured enough to begin the combining process. “Roll out a number of seed samples, 100 to 500 seeds per sample, and check the swath in a number of locations throughout the entire field. Low lying areas most often will take longer to cure than high slope areas. Ideally, once green seed contents are less than 2 per hundred seeds and moisture of the seed is less than 9%, it is time to combine and complete the harvest of the field.”
If harvest is late, as it is in some parts of the prairies, and achieving a #1 grade through further curing in the swath appears unlikely, growers can check online for the standards on other grades that may be achievable.
