Efficient use of nitrogen ranks right up there with seeding rates when it comes to increasing canola yields, an Agriculture and Agri-Food Canada researcher told the Alberta Canola Industry update recently.
Neil Harker, a researcher in weed ecology and crop management, recently worked on a study comparing the yield payback from fertilizer levels, seeding rates and fungicide applications.
The study was done in eight locations across Western Canada, with crops in a canola/wheat/canola rotation or in continuous canola. Data was collected in 2008 and 2010.
In order to test nitrogen, sites were given 100 per cent of their nitrogen requirements or 150 per cent of their nitrogen requirements. Edmonton and Lacombe hit their target yields with 100 per cent nitrogen. All sites except Swift Current increased yield when 150 per cent nitrogen was added, but the yield increase wasn’t substantial in 2008. When the researchers looked at the economics of yield increases that occurred from adding more nitrogen, they found an economic benefit at only three of the eight sites in 2008.
In 2010, five of the eight sites hit the target yields with a 100 per cent nitrogen regime.
“Conditions were much better for increasing nitrogen at every single site and some were substantially higher,” Harker said. “It would suggest that if you had extra money and wanted to put it into inputs, nitrogen would be No. 1,” Harker said.
All of the sites except Lacombe showed an economic payoff with an increase of nitrogen. When the data was crunched, all of the sites with extra nitrogen produced higher yields.
However, when higher nitrogen rates are used, oil concentration was reduced. “That was consistent across the whole study,” he said. “It was also interesting to me that the higher oil concentrations improved with rotation. That was very consistent, as it was for yield,” he said.
Researchers also found that high organic matter and cooler temperatures improved yields.
All of the four highest-yield sites had the lowest number of days over 30 C. “Temperature and organic matter were well correlated with yield. You can see with some of the increases in soil organic matter which suggests cool conditions in some cases, because organic matter doesn’t burn off as well,” said Harker.
When the researchers looked at the averages from the eight locations in 2008 and 2010, they found seeding rate and adequate nitrogen rates had a positive impact on both yield and oil concentration. In 2008 and 2010, an increase from 75 seeds to 150 seeds resulted in larger yields.
Canola seeds only have about 50 per cent emergence, which is low compared to other crops so higher seeding rates also increased yield.