Harker: Canola Sustainability - Risk Mitigation and Canola Sustainability All Phases Rotations
Date: April 2013
Term: 12 years
Status: Completed
Researcher(s): K.Neil Harker, John O’Donovan, Kelly Turkington, Agriculture and Agri-Food Canada (AAFC), Lacombe AB, Robert Blackshaw, Newton Lupwayi, AAFC Lethbridge, AB, Eric Johnson, AAFC Scott SK, Yantai Gan, AAFC Swift Current, Gary Peng, AAFC Saskatoon SK, Byron Irvine, Ramona Mohr, AAFC Brandon MB
SaskCanola Investment: n/a
Total Project Cost: n/a
Funding Partners: WGRF, Canola Cluster
Project Summary
Growing canola in tighter rotations increases risks and can dramatically decrease yields. Researchers conducted two 6-year studies to determine the agronomic and economic implications of growing canola in "tight" rotations. Researchers found that production and economic risks were higher in continuous canola or canola in a two-year rotation depending on the variety and location. The final results will be completed at the end of 2014 and are expected to confirm preliminary results.
Growing canola in tighter rotations increases risks and can dramatically decrease yields. However, given the superior profits of growing canola versus almost any other crop, growers are tightening their canola rotations.
Neil Harker with Agriculture and Agri-Food Canada (AAFC) in Lacombe, Alberta led two six-year studies at five sites (Lacombe and Lethbridge, AB, Scott, Melfort and Swift Current, SK) to determine the agronomic and economic implications of growing canola in "tight" rotations. Researchers also wanted to determine crop sequence effects on canola and implications for other factors such as diseases, weed population shifts and insect pests. The studies were completed at the end of 2013 with final results available in 2014.
Canola Sustainability - all phases rotation study (Funded by WGRF)
The first 'all phases rotation' study was initiated in 2008 at five sites (Lacombe and Lethbridge, AB, Scott, Melfort and Swift Current, SK), which compared different canola rotation frequencies and sequences. Continuous canola was compared with canola growers every second or third year in rotation with wheat, barley or pea crops. Data collection included: crop emergence, crop density, weed density every year, and weed biomass and microbial diversity (Years 3 and 6 only).
Treatments
1. Continuous Liberty Link (LL) canola
2. Continuous Roundup Ready (RR ) canola
3. LL canola-Hard red spring (HRS) wheat rotation (repeated 3 cycles)
4. HRS wheat-LL canola (repeated 3 cycles)
5. RR canola-HRS wheat (repeated 3 cycles)
6. HRS wheat-RR canola (repeated 3 cycles)
7. LL canola-Pea-Barley (repeated 2 cycles)
8. Pea-Barley-LL canola (repeated 2 cycles)
9. Barley-LL canola-Pea (repeated 2 cycles)
10. RR canola-Pea-Barley (repeated 2 cycles)
11. Pea-Barley-RR canola (repeated 2 cycles)
12. Barley-RR canola-Pea (repeated 2 cycles)
13. Lentil (CF)-HRS wheat-LL canola-Pea-Barley-RR canola (1 cycle)
The preliminary study results showed that production risks are higher and yields decreased as any of the rotations moved to a more continuous type of canola system. By the end of three years of continuous canola, the yield decreases were quite dramatic. Researchers expect these results are likely to be confirmed in the last year of this study. The final results will be completed at the end of 2014s.
Risk Mitigation Study (Funded by Canola Cluster)
The risk mitigation rotations experiment looked at factors that could mitigate the risk of growing a high frequency of canola in tight rotations. The experiment was conducted at the same five sites as the first study, plus an additional one at Brandon, Manitoba. The experiments included various risk mitigation treatments (growing different canola cultivars in alternating years and growing mixtures of canola cultivars within a given year). Data collection included: insect infestation levels, disease assessments, crop maturity date, grain yield, % oil content, % protein content, fatty acid profiles (Years 3 and 6 only).
Treatments (repeated for 2 rotation cycles)
1. RR1-RR2-RR3 canola cultivar rotation
2. LL1-LL2-RR3 canola cultivar rotation
3. CF1-CF2-RR3 canola cultivar rotation
4. RR1-LL1-RR3 canola cultivar rotation
5. RR1-CF1-RR3 canola cultivar rotation
6. LL1-RR1-RR3 canola cultivar rotation
7. LL1-CF1-RR3 canola cultivar rotation
8. RR1&2-RR1&2-RR3 canola mixture rotation
9. LL1&2-LL1&2-RR3 canola mixture rotation
10. RR1&2-CF1&2-RR3 canola mixture rotation
11. HRS wheat-LL1-RR3 rotation
12. Pea-HRS wheat-RR3 rotation
13. HRS wheat-HRS wheat-RR3 rotation
14. Westar canola-Westar canola-RR3 rotation
*RR=Roundup Ready; LL=Liberty Link; CF=Clearfield. Numbers 1-3 represents different cultivars within a herbicide-resistant canola system. **All treatments have RR3 canola in the third year to allow unbiased comparison of accumulated treatment effects from years 1 and 2.
Preliminary results from the risk mitigation study show there are no substantial benefits for growing different canola cultivars in alternating years or growing mixtures of canola cultivars within a given year. Researchers found almost the same reduction in yield from growing continuous canola whether using mixed cultivars or rotated herbicide tolerant systems every year.
The preliminary results also showed that blackleg incidence was lower for any rotation at all, while root maggot damage was lower when there was a minimum two-year break between canola crops.
Overall, early indications are that production risks are higher in continuous canola or canola in a two year rotation depending on the variety/location; these results are expected to be confirmed in the last year of this study at the end of 2014.
Figure 1. Influence of canola frequency in the rotation on blackleg incidence – Lethbridge 2011. Columns under the same statistical letter were not significantly different.
Figure 2. Influence of number of non-canola years in rotation on root maggot damage on RR or LL canola roots.
Scientific Publications
Dosdall, L. M., K. N. Harker, J. T. O'Donovan, R. E. Blackshaw, H. R. Kutcher, Y. Gan, and E. N. Johnson. 2012. Crop sequence effects on root maggot (Diptera: Anthomyiidae: Delia spp.) infestations in canola. J. Econ. Entomol. 105:1261-1267.
Full Report PDF: n/a