Holzapfel: Investigating Wider Row Spacing in No-Till Canola: Implications for Weed Competition, Response to Nitrogen Fertilizer and Seeding Rate Recommendations (2013-2016)
Date: March 2017
Term: 4 years
Status: Completed
Researcher(s): Chris Holzapfel, Indian Head Agricultural Research Foundation and William May, Agriculture and Agri-Food Canada, Indian Head SK
SaskCanola Investment: n/a
Total Project Cost: n/a
Funding Partners: n/a
Project Summary
A multi-year study was initiated in 2013 at Indian Head to evaluate the impacts of wider row spacing on canola (Brassica napus) performance and investigate implications for seeding rate, N fertilizer and weed management recommendations. The results indicated that canola is relatively insensitive to increasing row spacing and there are many factors to consider in determining the optimal row spacing for individual farms. Pros and cons exist for both narrow and wide row spacing – this is a complex issue that can affect entire production systems and, therefore, there is no likely single optimal row spacing for all farm operations.
Several past research projects focused on row spacing research for canola (Brassica napus). However, combined improvements in genetics, seeding/fertilizing equipment and weed control options over the past twenty years support revisiting the topic of row spacing in canola. Relevant research should be conducted under zero- or minimum-tillage continuous cropping systems and utilize seeding equipment with side-banding capabilities along with modern, herbicide tolerant hybrids.
A multi-year study was initiated in 2013 at Indian Head to evaluate the impacts of wider row spacing on canola performance and investigate implications for seeding rate, N fertilizer and weed management recommendations. Three separate field trials were conducted where row spacing levels of 25, 30, 36, 41 and 61 cm were combined with varying side-banded urea rates, seeding rates and in-crop herbicide treatments. For all trials, a glufosinate ammonium tolerant (Liberty-Link™) canola hybrid was seeded using a SeedMaster plot drill at a target rate of 115-120 seeds/m2.
Generally, the research showed that canola plant populations declined as row spacing was increased. When averaged across all years and treatments, plant populations declined by 28 per cent, from 85 to 62 plants/m2, when row spacing was increased from 25 cm to 61 cm. Increasing row spacing also resulted in slight but significant delays in flowering and maturity. However, row spacing effects on seed yield were small and, in some cases, non-significant, and were always considerably less than environment or other management effects. The results also suggest that seeding rates should not likely be reduced below typically recommended rates as row spacing is increased. However, there was little benefit to using seeding rates exceeding 90 seeds/ m2 when planting canola at 61 cm row spacing.
The results of the side-banded N treatments showed a significant reduction in plant densities with increasing rates of side-banded N in all three years. While this occurred at all row spacing levels, there was evidence that plant populations started to decline at lower N rates at the widest row spacing compared to the other rates. Despite the effects on emergence, canola responded well to side-banded N with sequentially increasing yields right up to 150 kg/ha N in all three years, including the trials with canola at 61 cm spacing. Overall, the results of this study suggest that N requirements of canola are likely similar regardless of row spacing; however, extremely high rates of side-banded N combined with wide row spacing can increase risk of seedling injury.
Canola was also grown at each row spacing level with and without herbicide to assess potential impacts on crop competition with weeds. It is generally accepted that the ability of crops to compete with weeds may be compromised at wide row spacing; however, this study did not show any practical, short-term effects of row spacing in this regard that could not be managed with well-timed herbicide applications. Failure to control weeds resulted in an overall average yield losses of 21% on average with similar yield loss observed regardless of row spacing.
24-inch row spacing
Narrower row spacing consistently produced amongst the highest yields, particularly when combined with high rates of side banded N; however, row spacing as wide as 61 cm was always viable under the environmental conditions encountered and when combined with timely, effective weed removal. Canola growing on wider row spacing did take longer to achieve canopy closure, which does have drawbacks; however, the effects on maturity were negligible. For growers dealing with or looking to prevent the development of herbicide tolerant weeds, narrow row spacing can be an important component to integrated management strategies.
10-inch row spacing
Many of the major drawbacks to narrower row spacing are more logistic than agronomic (i.e. higher equipment operating costs, increased horsepower requirements/fuel use); however, narrow row spacing can also make it considerably more difficult to seed into heavy crop residues. If slightly wider row spacing can lead to better seed placement in heavy residues, increased organic matter retention, more timely seeding, better utilization of existing equipment, lower seed-bed preparation requirements etc., there could be numerous, longer-term benefits not accounted for in this study.
Generally, the research concludes that canola is relatively insensitive to increasing row spacing and there are many factors to consider in determining the optimal row spacing for individual farms. Pros and cons exist for both narrow and wide row spacing – this is a complex issue that can affect entire production systems and, therefore, there is no likely single optimal row spacing for all farm operations.