Ever since no-till prod uction methods started gaining popularity, growers have been stretching seed row spacing because of the advantages offered by wider widths. Today, farmers are seeding at nearly double the old seven-inch standard compared to a couple of decades ago. But are they risking reduced yields due to a low level of seedbed utilization?
That’s the subject of a field study at the Agriculture and Agri-Food Canada Research Farm at Indian Head, Sask. With two years of data compiled so far, some trends are becoming clear, research scientist Guy Lafond told attendees at the SeedMaster’s Master Seeders Conference in Regina last November.
The researchers have used oats as a test crop but the results can be applied to most Prairie cereals, and are evaluating row spacing of 10, 12, 14 and 16 inches in terms of nitrogen uptake, yield, grain quality and other factors.
“In 2009, there was no (yield) difference going from ten inches to 16,” said Lafond. “But in 2010, we did see some drop at 16 inches. One possible reason for the lower yields at 16-inch spacing in 2010 was because we weren’t able to get into the field and harvest when we wanted. The stems started breaking and many panicles were closer to the ground as row spacing increased, making it difficult for the plot combine to pick them up. This was more so at the high nitrogen (N) rates. If we look at N response over the two years, we only saw a yield depression at 16 inches.”
That means yields remained consistent at the optimum N rate up to 14 inch spacing.
FACTOR SBU INTO FERTILITY LEVELS
The trials are scheduled to continue for one more year, but Lafond thinks some conclusions can already be drawn.
“A wider row spacing will be better if you can take advantage of what it has to offer under no-till,” he said, adding 14 inches seems to be the widest producers should consider for the time being.
In the trials, N was placed 1.5 inches to the side and three-quarters of an inch below the seed row, which is a common placement style used by many drills now on the market. Amounts of 20, 40, 60, 80 and 120 kilograms per acre of actual N were tested.
As row spacing increases, higher concentrations of fertilizer need to be placed along- side each row even though the amount applied per acre is constant. The trials looked at the risks of placing those larger amounts of N close to seed.
“You’re increasing the amount of product beside the row, so it’s important we test the effects of higher concentrations,” says Lafond.
Overall, the results showed placing seed and fertilizer in this particular configuration along a single row was safe. However, Lafond pointed out increasing the row spacing could cause problems for those using seed-placed fertilizer. As row spacing increases, seed-bed utilization decreases. Therefore, the amount of fertilizer that needs to be placed in the seed row may have to be reduced as widths increase. But depending on the row spacing used, it may not be possible to put down the required amount. That could keep farmers who use this method working with a narrower spacing.
Regardless of which row spacing is used, adequate plant populations need to be maintained. The trials targeted oat plant stands of 300 per square metre. But 200 to 250 is the optimum number for wheat.
“It’s always better to have a higher than lower plant population,” Lafond said.
Understanding that the benefits offered by a wider spacing can be taken advantage of without compromising yield is the real good news to come out of these trials, he said. One of the most important of those advantages is no-till drills with wider row spacing require fewer openers, which reduces horsepower requirements and fuel consumption while seeding.
“You can pull a wider implement with the same amount of horsepower,” he noted. “That’s important on the Prairies. It gives you (the equivalent of) an extra couple of seeding days. And it also allows me to cut my stubble higher increasing combine efficiency.”
Leaving tall standing stubble and seeding between the previous year’s rows offers some significant microclimate advantages for young seedlings.
“In years when it’s really dry, that’s when it’s important,” said Lafond, pointing out farmers doing so would likely see a yield advantage.
Inter-row seeding also increases the likelihood producers can maintain a constant seeding depth at higher speeds. The standing stubble between the openers significantly reduces the chance dirt will be thrown on top of adjacent seed rows.
Cory Beaujot of SeedMaster said most of that company’s customers are currently asking for 12-inch row spacing, but a few are now looking for wider 14-inch designs. Lafond cautioned this trial has only looked at cereal crops, though.
“We don’t know what the ideal plant spacing is for canola,” he said. Until farmers have that information, 12-inch spacing is likely to remain the most popular.
Research looking into the effect of row spacing on weed growth is expected to begin in 2012.
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