Winter canola acres continue to increase in the southern Great Plains region. This article summarizes the impact of production practices on canola establishment, winter survival, and yield. Crop rotation, planting dates, tillage systems, seeding rate, row spacing, and cultivar selection are some of the main production factors that can potentially influence canola productivity.
1. Crop rotation
The benefit gained by rotating canola with winter wheat is a major factor contributing to canola expansion in the southern Great Plains. Information from Oklahoma showed an increase in the number of tillers and forage dry matter for winter wheat when planted after canola. Another study from Oklahoma showed a 10% average yield gain for wheat grown in rotation with canola as compared to continuous wheat (Fig. 1). Information from K–State (2012 season) documented yield improvements in the range of 10 to 30% for wheat after canola as compared with continuous wheat (Fig. 1). Similar winter wheat yield gains following canola have been documented in other states as well (e.g. in Washington state there was an increase of 13 bu/acre).
Figure 1. Winter wheat yield response to previous crop.
2. Planting Dates
The planting window for canola is one of the most critical components of crop production for guaranteeing good establishment and winter survival. Data from K–State, at Manhattan, showed that optimum planting dates for adequate canola winter survival are between mid- to late-August and mid-September (Fig. 2). Reductions in winter survival were documented when the planting date was early October. Good correlation between canola yields and winter survival was observed for mid-late August, early- and mid-September planting dates; while yields were not the same when canola was planted in early October.
For southwest Kansas, greater than 50% winter survival was achieved when canola was planted mid-August to early September (3-yr average, 56-57%). Planting canola after the first week of September increased the likelihood of winterkill. For three years, planting canola on October 1 resulted in an average of 17% winter survival (Holman et al., 2011).
Figure 2. Canola yields and winter survival as related to the planting date (Manhattan -- 2009/10, 2010/11, and 2011/12; Stamm and Roozeboom, 2012).
3. Tillage systems
For the Manhattan area, a 3-year experiment found that tillage system influenced canola yield and winter survival responses. There were reductions in winter survival and final yield when canola was planted late under low disturbance no-till versus disking. Tillage has a major influence on yield and winter survival rate when planting late.
In Oklahoma, high-disturbance direct seed drills with a shank opener resulted in more consistent seed placement, excellent residue and fertilizer management, more consistent emergence, improved initial and final stands, winter survival rates, and final yields for both conventional and no-tillage planting systems. Winter survival was often not satisfactory using low-disturbance direct seed drills.
In southwest Kansas, conventional tillage had a small 8% yield benefit over no-till (1,556 lbs/acre vs. 1,434 lbs/acre) when a coulter was used ahead of the direct seed opener. Using light tillage or coulters ahead of row openers increased winter survival and yield at Garden City (Table 1). The 8-inch row spacing showed greater yields when a coulter was used ahead of the disk opener, but the benefit of planting in 8-inch rows disappeared when the coulter was not utilized.
Table 1. Canola response to drill setup (John Holman, Southwest Research-Extension Center).
|
|
Coulter ahead of disk opener |
|||
|
Row spacing |
With |
Without |
With |
Without |
|
|
Winter survival (%) |
Yield (lbs/acre) |
||
|
8-inch |
53 |
44 |
1134 |
733 |
|
12-inch |
29 |
26 |
818 |
784 |
|
16-inch |
43 |
20 |
989 |
723 |
A 3-year analysis of tests investigating the effects of planting dates, genotypes, and tillage systems on canola yields documented a clear advantage in performing light tillage (disk) for improving grain yields and winter survival regardless of the planting date evaluated (Figure 3). The yield advantage of disk versus no-till (minimal disturbance) was greatest, in absolute terms, for early September as compared to mid-late August and mid-September planting dates. In relative terms, the importance of better residue distribution using a disk in improving yields is greatest when the crop is planted outside of the optimum planting window (e.g. late October).
The yield advantage documented for minimum tillage is related to a better residue distribution, better stand establishment (plant uniformity as a critical point), increased fall vigor, and better winter survival. In addition, microclimate effects (colder temperatures around plants) and possibly residue allelopathy may affect yield under minimal disturbance no-tillage, lowering the maximum potential yield to be attained as compared with the minimum tillage with residue removed.
Figure 3. Canola yield response to planting dates and tillage systems (Manhattan -- 2009/10, 2010/11, and 2011/12; Stamm and Roozeboom, 2012).
4. Seeding rate
Canola seeding rate is primarily determined by the seed size (grams per 1000 seeds) and the seed weight per acre (lbs/acre). Optimum seeding rate for open pollinated varieties is about 400,000 to 500,000 seeds/acre; while for hybrids, the optimum seeding rate is about 200,000 to 350,000 seeds/acre. Currently, most canola producers in the Great Plains region base their seeding rate decision on seed weight (lbs/acre), with an optimum seeding rate between 3 to 5 lbs/acre, depending on the variety/hybrid. Information from Oklahoma showed an interaction between seeding rate and drill type. Maximum yields were achieved with the use of the high disturbance (JD 1870) direct-seed drill at a rate of 5 lbs/acre (Fig. 4).
Figure 4. Canola yield response to drill type and seeding rate across five different sites (Oklahoma State University).
Canola yield response to spring plant density is summarized from studies carried out in Garden City and Manhattan (Figure 5). There was no clear trend in canola yield response to diverse spring plant densities regardless of the varieties, planting dates, and tillage systems used.
Figure 5. Canola yield response to spring plant density across growing seasons, varieties, planting dates, and tillage systems.
5. Cultivar selection
Cultivar selection is one of the most critical factors for producing winter canola. Cultivar selection greatly influences canola final yield. The most important traits to consider when selecting a cultivar are: yield, winter survival, herbicide resistance (sulfonylurea residual tolerance, Round Ready, or Clearfield), relative maturity, and oil content. A study performed during three growing seasons in Manhattan did not show any strong genotypic differences in response to tillage systems. Minimum tillage (disk) out-yielded no-till (with minimal disturbance) for all genotypes evaluated. In a simple comparison, four varieties are displayed in Figure 6 to depict the effect of the tillage systems. The hybrids Chrome and Sitro, in absolute terms, had greater yields when the planting system was minimum tillage (disk) as compared with no-till across three growing seasons (2009-10, 2010-11, and 2011-12). More information about cultivar and planting tillage systems is currently under investigation and will be available at the conclusion of the 2013-2014 growing season.
Figure 6. Canola yield response to cultivar and tillage systems (Manhattan -- 2009/10, 2010/11, and 2011/12; Stamm and Roozeboom, 2012).
Summary
In summary, planting date and cultivar are two of the most important components for successful canola establishment, fall vigor, winter survival, and yield. A practical rule for planting date is to plant canola about a month ahead of normal winter wheat planting time. For insurance purposes, optimum planting date is between August 25 and September 25 for southwest Kansas, and September 1 to September 30 for central Kansas. For Barber, Harper, and Sumner counties, canola can be planted between September 10 and October 10. If canola is planted under no-till, plant a week or so earlier than the optimum date. For cultivar selection, the main traits to look for are yield, winter hardiness, relative maturity, and oil content.
It is critical to use planting equipment that can handle residue. Having less residue in-furrow increases the likelihood of winter survival. Residue between the seed rows does not appear to have a negative effect on winter survival or yield.
Seeding depth of 0.5-1.5 inches and uniform seed placement are also important for successful canola establishment.
Tillage is recommended for distributing the previous crop’s residue, ensuring adequate winter survival, and maximizing canola yields, but it is not required if the seed row is clean of residue.
Row spacing (6- to 15-inch) has not resulted in large yield differences. Wider rows can help in providing more precise seed metering and/or residue management. Narrow rows can improve weed control, and may improve winter survival and increase yield under higher yielding conditions.
Plant density did not show any consistent trend across years, thus seeding rates around 3.5 to 5 lbs/acre seem to be reasonable for producing an adequate canola stand in narrow row spacing and using open pollinated varieties. Because of intra-row competition, seeding rates should be reduced to 1.5 to 3 lbs/acre in 30-in row spacing. More information on seeding rate and variety interactions will be available at the conclusion of the 2013-2014 growing season.
For further information, see the revised Great Plains Canola Production Handbook, at your local Extension office, or: http://www.ksre.ksu.edu/bookstore/pubs/mf2734.pdf
Ignacio Ciampitti, Crop Production/ Cropping Systems Specialist
ciampitti@ksu.edu
John Holman, Cropping Systems Agronomist, Southwest Research-Extension Center
jholman@ksu.edu
Kraig Roozeboom, Crop Production Agronomist
kraig@ksu.edu
Mike Stamm, Canola Breeder
mjstamm@ksu.edu
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