Precision planters demonstrated superior depth control and enhanced seed-to-soil contact, while facilitating consistent seed placement at specific intervals along the seed row. This uniform distribution promotes better resource utilization and can facilitate rapid crop growth and help obtain canopy closure quicker than other methods.

Additionally, these attributes directly contribute to improved stand establishment. We saw significantly improved canola stand establishment when measured at the 2-4 leaf stage. Furthermore, post-harvest stubble counts showed an increased stand density overall. We observed similar trends of improved performance with precision planters under both rainfed and irrigated conditions. 

In our dryland trials, canola stand establishment at the 2-4 leaf stage was 12-24% better & canola stand density at maturity was 13-16% better. Meanwhile, stand establishment improved by 24% (compared to disc hoe seeding) and stand density by 15-17% at the same stages under irrigation.

a) 2-4 leaf stage

b) at maturity (post-harvest stubble count)

Figure 1. Plant density of canola at the a) 2-4 leaf stage and b) at maturity under irrigated and rainfed conditions averaged across study locations (Lethbridge, Bow Island, Brooks, and Stirling) and years (2021-2023) for different seeding systems including disc hoe (DH), narrow knife (NK), precision planter (PP), and spreader (SP). Different letters within each irrigation system indicate statistically significant differences in means at p < 0.05.

However, the improved growth performance observed did not improve canola yield.

Canola yield was lower in both irrigation and dryland trials with precision planting. Under irrigation, the disc hoe opener had 15% higher yields while the narrow knife and spreader openers had 7-8% higher yields compared to the precision planter. Similarly, the disc hoe opener improved yields by 18-24% compared to all other seeding methods on our dryland sites.

The reduced yield may be attributed to the higher row widths resulting from the precision planter. 15" rows creates more inter-plant competition between rows and thus may decrease seed yield. Drought conditions may be another contributing factor to the low yields, as growing season precipitation ranged from 41-88% of the respective long-term (30 years) average of study locations throughout the duration of this project. Previous studies have established that precision planting is less effective compared to air seeding under water-limited conditions (Dhillon et al. 2022).

Tillage methods did not have a notable impact on soil properties including soil temperature and soil moisture. While conventional tillage and strip tillage had higher soil temperatures compared to no-tillage, there was little difference as cross correlation between temperature curves was very high within the growing season.

Soil moisture content was marginally higher in the no-tillage system than in the other tillage systems; however, these differences were not statistically significant. Furthermore, tillage systems did not seem to impact canola growth and yield. Crop growth parameters like stand density (2-4 leaf stage) and maturity did not have statistically significant outcomes of tillage. Similar results were observed with FGCC at 4-5 weeks and 6-8 weeks after seeding.

Under rainfed conditions, there was an increase in canola yield under no-tillage compared to conventional and strip tillage (13% and 9% increases, respectively). This increase may be linked to better moisture retention, which may have been critically important due to the drought conditions that existed for the majority of the project duration.

Meanwhile, under irrigation, canola yield was not influenced by tillage systems. However, no-till and strip till are expected to provide ecological benefits like reduced soil erosion, improved soil health, and carbon sequestration in the long term.