Precision planted canola compared to air drills

Under  irrigated and high-precipitation conditions, canola yield from 12 inch narrow-row precision planted canola was 10% higher than canola seeded with a 12 inch row air drill. However, under more water-limited conditions, yield from air drill seeded canola was equal or higher than the precision planted canola. Seeding with a 20 inch wide-row planter resulted in poor stand establishment and low seed yield under both irrigated and dryland conditions.

Planters are commonly used to seed corn, soybeans, dry beans, and sugar beets, and some farmers on the Prairies are now using them to seed canola. However, there is a lack of research on the benefits of using a planter for small seeded crops like canola.

The objectives of this research was to determine canola plant density at different seeding rates, how plant density affects seed yield, and to compare precision planter and air drill impacts on plant density and seed yield.

Field experiments were conducted at Lethbridge and Medicine Hat, Alberta under dryland conditions, and an irrigated Lethbridge site from 2016 to 2019 for a total of 12 site-years. A zero-till air drill was compared to a Monosem planter.

The zero-till air drill was fitted with double shoot, disc/hoe openers and an on-row packer wheel with double-shoulder offset to close the furrow. It used an individual row metering system to deliver the seed. The air drill was set with 12 inch (30.5 cm) row spacing.

Row spacing on the Monosem planter was either 12 inch (30 cm) or 20 inch (50.8 cm) row spacings. It used 15 inch (38.1 cm) diameter disk openers. An aluminum wheel and rubber V closing wheel provided packing of the seed row.

Canola was seeded during the first 2 weeks of May at five different seeding rates of 2, 4, 6, 8, and 16 seeds/ft2 (20, 40, 60, 80, and 160 seed/m2). Recommended rates of nitrogen (N) were side-banded, and phosphate (P) was seed-placed.

Analysis of the results found that there was a significant site-year interaction of seeding rate and planter type on plant density and yield. This indicated that growing conditions played a major role in canola production as influenced by seeding rate and seeding equipment. As a result, statistical analysis was conducted separately for each site-year.

Plant density better with narrow rows

In many of the site-years, the lowest seeding rates did not reach the Canola Council of Canada’s recommended stand establishment of 5 to 8 plants/ft2. Given the low seeding rates and an expected seedling emergence rate of 40% to 60%, this was not surprising. In a few cases, the 8 seeds/ft2 rate produced recommended stand establishment, but 16 seeds/ft2 rate most often reached optimum plant density. The exception was with the wide row planter, which rarely reached the optimum plant density, even at the highest seeding rate.

To compare the impacts of row spacing and seeding equipment on plant density, seeding rates were averaged together. Narrow-row precision planted canola had higher plant density than the air drill at 3 site-years, but no significant differences at the remaining 9 site years. Additionally, the narrow-row precision planted canola had higher plant density than the wide-row precision planted canola at 3 site-years with no differences at the remaining 9 site years. This suggests that the narrow-row precision planter may lead to better stand establishment in canola compared with the air drill and wide-row precision planter.

Highest yields for higher seeding rates

Canola yield was significantly higher at 7 of 12 site years as plant density increased. The highest yields were obtained with the highest seeding rates, which was a reflection of better stand establishment with higher seeding rates.

At the other 5 site years, there was no relationship between plant density and yield. Three of these site-years had poor yields, and 1 site-year at Irrigated Lethbridge had very high yields.

Yield density for different planters at 12 site-years

AD, air drill; PP nr, precision planter 30.5 cm row spacing; PP wr, precision planter 50.8 cm row spacing); (IR, Lethbridge irrigated; LB, Lethbridge dryland; MH, Medicine Hat dryland).

Source: Dhillon et al. 2022

The relationship between plant density and yield did not show statistically significant differences between the air drill and precision planters.

Planter versus air drill

Statistically significant yield differences were observed between the narrow-row planter and air drill at 7 site-years. At 5 of these site-years, seed yield was higher for the narrow-row planter, while the air-drill had higher yield at 2 site-years. Further analysis found that these differences were attributed to environment. At the 4 irrigated site-years, the narrow row precision planter yield was higher at 2 out of 4 site-years than the air drill, with no statistically significant differences in the remaining 2 site-years. Narrow-row precision planted canola yielded an average 10% higher on the irrigated sites — 8.2 bu/ac (463 kg/ha) — than the air drill seeded canola.

Under dryland conditions, the average canola yield was similar between narrow-row planter and air drill seeded canola. The narrow-row planter yielded 34.9 bu/ac (1960 kg/ha) and the air drill produced yields of 34.8 bu/ac (1958 kg/ha).

The seed yield for the wide-row precision planter was lower than the narrow-row planter at 9 of 12 site-years, with no statistically significant difference at the remaining 3 site-years. The poor performance of the 20 inch wide-row canola could be attributed to poor stand establishment and high in-row plant density that leads to increased inter-plant competition for resources.

Overall, narrow-row planters may outperform air drills under irrigation and high-moisture conditions, although the air drill performed as well or better than the narrow row planter under more water-limited growing conditions. Seeding canola in 20 inch rows would not be recommended.

Funding for this project was provided by Alberta Canola, Saskatchewan Canola and Manitoba Canola through the Canola Agronomic Research Program (CARP) and administered by the Canola Council of Canada (years 1 to 3) and Canadian Agricultural Partnership (CAP) (year 4).

Gurbir Singh Dhillon, Lewis Baarda, Mike Gretzinger, and Ken Coles. Effect of precision planting and seeding rates on canola plant density and seed yield in southern Alberta. Canadian Journal of Plant Science. e-First OPEN ACCESS

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