Canola harvesting techniques
Maximizing yield and quality at harvest and balancing all of the variables can be challenging. However, planning ahead and timing swathing and straight cutting operations properly can reduce losses and improve profitability.
For growers who plan to swath all or a portion of their canola crop, the main recommendation is to get that timing right. Research shows swathing canola when the main stem is 50 to 70 per cent colour change will provide yield and quality improvements. When possible, waiting until canola is at 60 per cent seed colour change on the main stem gives more seeds a chance to reach full maturity, which means higher yield and reduced green seed counts.
“Swathing ahead of that 50 to 70 per cent seed colour change on the main stem will cause a yield drag,” explains Angela Brackenreed, agronomist with the Canola Council of Canada. “It is very important for growers to educate themselves on how to assess seed colour change, which is considered any amount of brown on the seed. Get out into the field and crack open some pods to make the best assessment.”
Brackenreed stresses that pod colour change is not an accurate indicator, because although visually the pods can look mature or immature, when you actually crack open a pod the seeds can look very different. The number one recommendation for growers is to time swathing to where the majority of the yield will be.
Timing to reduce shattering losses is important whether growers plan to swath or straight cut their crop. “The longer a crop stands, obviously the more vulnerable it can be to shatter loss,” says Murray Hartman, oilseed specialist with Alberta Agriculture and Rural Development. “Growers realize that, and looking at the data, losses on average are five or six per cent, which is not a small amount. So growers should have in the back of their mind – whether they plan to straight cut or swath – how to reduce shatter loss.”
Don’t swath too early, particularly when the densities in the field tend to be on the low side with a lot of branching. “Even using the more recent guidelines of waiting for 50 to 60 per cent colour change on the main stem may not be late enough for a thin stand if there is lots of material on the branches, both from the standpoint of yield and quality,” explains Hartman. “If growers have a thin stand, it is better to delay swathing even if there is some shatter loss of the first pods. These tend to be on the lower part of the main raceme and are the most protected from wind, so I don’t think those are the ones that are of a big concern from delaying. That’s why some growers switch from swathing to straight cutting and get a yield improvement. If they would have delayed swathing to a more appropriate timing, the yields would likely have been the same.”
Shattering losses are not just about yield, but also the impact on subsequent crops as well. “Those seeds that shatter can become volunteer weeds that require effort and herbicide costs to control them,” notes Hartman. “If not controlled, those volunteers that do grow can contribute to a green bridge for diseases like blackleg and clubroot. When growing hybrids, there can be some segregation to parental types in the volunteers where one may not have the disease resistance, adding to the risk of a green bridge.”
For straight cutting, the most important consideration is field selection and variety choices. Ideally, canola is straight cut when it is dry, which is 10 per cent moisture or lower to be safe for storage. “Assess a field for straight cutting just prior to swath timing; then, if the field doesn’t meet the criteria, you can still go in and swath at that ideal 60 per cent colour change,” explains Brackenreed. (Bayer CropScience recommends 50 to 60 per cent colour change.) “Fields suitable for straight cutting should have uniform maturity through the field and good pod integrity, meaning little disease such as sclerotinia or alternaria that could cause the pods to be prone to shattering or dropping. Fields should have good density and be well knit together to minimize potential wind damage and shattering losses.”
Wind is a complex consideration and has impacts on both swathing and straight cutting operations. Hartman says that up to a certain point at about 40 to 50 mph wind, there will be some shatter losses in a standing crop. “However, if the wind is really strong, there can actually be greater losses with swathed crops because they start rolling and moving around, and the damage can be worse than if left standing. Predicting wind is difficult, but research trials show that it is about one-in-20 times when a wind event will be strong enough at harvest when the crop is still standing to cause significant shatter loss.”
There are new varieties specifically bred for improved shatter tolerance, and considering such a variety is a good strategy for straight cutting. InVigor L140P is one example of new varieties specifically bred for improved shatter tolerance. “This can be an important step in making straight cutting a more consistent practice and probably will result in a little higher yield on average and better quality because of leaving the crop standing longer,” explains Hartman. These varieties can also be a good strategy for swathed crops.
Brackenreed suggests that because growers like to try different varieties, they should experiment with different ones, testing them in their fields and finding the ones that work for them.
Having the flexibility for both swathing and straight cutting can be a benefit for time management and potential quality improvements. “The main benefit for moving to straight cutting is more about time management, with potential yield and quality improvements secondary,” says Brackenreed. “Straight cutting is likely not going to produce a consistent yield benefit on it’s own when compared to swathing at 60 per cent seed colour change. However, growers will see an indirect economic benefit by practicing straight cutting in combination with swathing, including less labour and machinery operation costs, as well as the opportunity to perfect timing of the swathed acres by moving some into straight cut acres.”
Moving some of those swathed acres into a straight cutting situation can really help with time management and helps move more of the swathed acres into that ideal time so you aren’t incurring the yield drag by swathing too early. Trying to get everything swathed in a short period of time often results in swathing some fields too early, some too late and only a small portion of the canola is swathed in that ideal time for maximizing yield. A combination of swathing and straight cutting can help maximize yields and quality across the acres.
Equipment for straight cutting varies, although some headers are better suited than others. “A narrow header for straight cutting is easier than a huge wide one especially on hills, and the deeper the header table the better in case of shatter loss, which will fall on the table rather than in front,” says Hartman. In Europe, cutter dividers are highly recommended for straight cutting.
Brackenreed adds that growers who don’t have specialty headers should not let that deter them from trying straight cutting for the first time. “You can be successful with any type of header, it just takes some patience, adjustments, playing around until you get it right, and eventually it will become just like anything else once you get used to it.”
Making the decision of whether to swath or straight cut depends on many variables and unknowns such as weather. Hartman adds that a grower’s propensity for risk of shatter loss may be the biggest one although there are a lot of “ifs” and “buts” – if there is a frost and the stems are green, if there is a shower or wet weather, if the straight combining equipment is already maxed out on cereal harvest, if the crop is still standing, and so on.
“It is never too late to straight cut; an over-ripe crop may suffer more shatter losses from swathing. So balancing a combination of swathing and straight cutting at the best timing for maximizing yield and quality along with growing shatter tolerant varieties may be a good solution,” he says.
Adds Brackenreed: “Every year, growers are able to get a lot of acres seeded in a short period of time in the spring, but when it comes to harvest, there isn’t always enough manpower or resources to harvest that same amount of crop in that short period of time. Timing it right is much easier said than done as every year there are fields with variability. Throw in risks such as frost and disease pressure, and all of these things add to the challenge of when to swath or straight cut. Planning ahead and timing swathing and straight cutting operations properly can reduce losses and improve profitability.”
January 7, 2015 By Donna Fleury