1Melfort Research Farm, Agriculture and Agri-Food Canada, Box 1240, Melfort, SK. S0E 1A0
2Prairie Agriculture Machinery Institute, Box 1150, Humboldt, SK. S0K 2A0
Direct, or no-till, seeding is growing rapidly as an effective means of crop production in western Canada. Clearing accumulated crop residues on the surface of a field has increased interest in seeding implements with wider row spacing. This research project was initiated to address the question, can equivalent grain yields be obtained when crop row spacing is increased from 6 or 8 inches to widths of 12 to 16 inches?
Spring wheat (cv. Katepwa) and barley (cv. Harrington) were seeded at four row spacings at six locations between 1994 and 1996. The trial locations were Foam Lake (Thin Black Loam), Naicam (Black sandy Loam) and Unity (Dark Brown Loam) in 1994, Elfros (Thin Black Loam) in 1995 and Wishart (Thin Black Loam) in 1996. Row spacing used were 6, 8, 12 and 16 inches. Wheat was seeded at 70 lb/ac and barley at 65 lb/ac. All trials were seeded using a pneumatic plot seeder with narrow (3/4 in) knife openers. Seed row fertilizer was applied as monoammonium phosphate (11-51-0) at a rate of 40 lb/ac, with all row spacings. Fertilizer N was applied as ammonium nitrate surface broadcast after seeding at a rate of 70 lb/ac. Crop emergence was determined at the 3-4 leaf stage of cereals, prior to in-crop weed control. At harvest grain yields were determined from small plot combine harvest, using 9, 7, 5 and 4 rows for the 6, 8, 12 and 16 inch row spacing, respectively. Grain yields were calculated based on the area occupied by the rows harvested.
Results from this research indicate that highest seedling numbers per unit area were measured with the narrowest row spacing for both wheat and barley. The effect of increasing row spacing on reducing seedling stand was greater for barley than wheat. Increasing plant population within rows with wide row spacing resulted in fewer surviving plants. An interaction between row width and location was recorded for both wheat and barley. With wheat, increasing row spacing resulted in an increase in seedling number up to 12 inch at four of the six trials, while at the remaining two it was the 6 inch row width that had the highest seedling number. For barley the 6 inch row width had the highest seedling numbers at three trials, while no difference was recorded at the remaining three. This variability in seedling stand reflects the effect that environment has on crop establishment.
Grain yields also declined with increasing row spacing, however, only at the 16 inch row width was the decline significantly different. Field observation from these trials indicated that on several occasions inter-row weed populations were higher with the 16 inch row spacing, indicating incomplete exploitation of available water by the cereal crop at this wide row width. No row width by location interaction was recorded for wheat or barley yield, indicating a common crop response over a wide range of environments and yield (5 - 53 bu/ac for wheat; 19 - 71 bu/ac for barley) conditions.
The maintenance of wheat and barley grain yields at row spacings of up to 12 inches can help to alleviate many of the problems experienced by farmers when seeding into heavy crop residue cover. Wider row widths also reduce implement draft requirements, allowing for energy savings in fuel and implement manufacture. Producers in the Parkland region of western Canada should be confident that they can use seeding implement row spacings of up to 12 inches without any adverse effects on wheat and barley grain yields.