While this three-year study was designed to compare three straight-cut headers and a swathed check, results found that using a shatter-tolerant variety was much more important than header type for lowering the risk from straight-combining canola.
The three-year project (2014-16) compared three header types for straight combining canola: rigid auger, draper and extendable knife. Treatments also included a swathed check. The test protocol involved harvesting strips in a randomized split-block design using two canola hybrids – standard InVigor L130 and shatter-resistant InVigor L140P – at two locations, Swift Current, Saskatchewan and Indian Head, Saskatchewan. Data collected included header loss, yield and seed quality.
Header loss. The rigid header had the highest losses overall, and was by far the worst for losses in the middle of the platform. Extendable knife and draper headers had lower losses in the middle of the platform, but all three straight-cut headers had fairly high losses at the crop dividers. In addition to comparing headers, the study also compared fixed, vertical knife and rotary knife dividers. Vertical knife and fixed dividers had lower losses than the rotary knife divider.
Yield. High variance in canola yield between site years was due, in most part, to hybrid choice and environmental conditions. No one header had the highest average yield in all situations, and the study found no consistent yield benefit for straight-cut versus swathed treatments.
At Swift Current, the shatter-resistant hybrid showed a 5 bu./ac. advantage when straight combined instead of swathed, but the standard or “typical” hybrid produced about the same yield when swathed or when straight combined using the extended knife or draper headers. Yields were lower for the rigid header.
At Indian Head, results for the shatter-resistant hybrid were about the same for all treatments, including swathing, but results for the standard hybrid were clearly better when swathed. A big reason for this was heavy winds that came after swathing but before straight combining at the Indian Head site in 2015 and 2016. This underlines the potential risk with standard varieties when they’re left standing in adverse environmental conditions.
Seed quality. Generally favourable conditions at Indian Head for all three years resulted in desirable seed moisture, green content, seed weight and oil content for all treatments. Environmental challenges at Swift Current in 2015 and 2016 meant the crop was harvested tough and with higher green counts. When Swift Current results were averaged over the three years, swathed canola had lower seed moisture than straight-combined canola, but straight-combined canola had lower green seed counts, higher seed weight and higher oil content.
The primary header-choice objective of the study came to this conclusion: Extendable knife and draper headers are better than rigid headers when it comes to reducing header losses for straight-combining canola.
A key aspect of the project was the comparison between straight-cut and swathed canola, and it concluded that no one system will produce the greatest yield in every instance. Swathed canola yielded better in some site years; straight-combined canola yielded better in others.
By including the comparison between shatter-resistant and standard canola hybrids, this study came to perhaps its most important conclusion: Growing a shatter-resistant hybrid will mitigate risk under ideal and adverse environments, and is likely more significant than header choice for successful straight combining of canola. The final report adds: “As there is no defined standard for shatter resistance in canola, it is important to evaluate individual varieties and note that varieties labeled as shatter resistant or shatter tolerant may not be a direct substitute for the variety used in this study.”