Canola producers who intend to plant this fall should hold off on applying sulfur until next spring, says a soil scientist with the North Dakota State University Extension Service.
Because of research results from NDSU and parallel studies in Canada, canola producers may want to re-evaluate the form of sulfur they apply next year.
“With spring-seeded canola, applying sulfur can be a tough problem. With dormant seeding, it’s a tougher problem,” said Dave Franzen, extension soil science specialist at NDSU.
“If you put sulfur on in the fall, you’re gambling that it’s not going to leach. During the last few years, that gamble wouldn’t have paid off.”
Read Also
Anti-separatist movement targets rural Alberta
Former deputy premier Thomas Lukaszuk’s anti-separatism Alberta Forever Canada petition campaign expects to run full steam ahead into the province’s farming regions
For dormant-seeded canola, producers have several springtime application options. They can apply ammonium sulfate granules before the crop emerges or early in the crop’s growth stage, when stems are still flexible. Franzen said aerial application also works for granules.
“You’re not going to get leaf burn from granules if the leaves are dry,” he said.
Similarly, spring-seeded canola can receive a broadcast application of ammonium sulfate before plants emerge.
Producers can also apply ammonium sulfate when seeding in the spring. However, the seed and fertilizer must be separated by at least 2.5 centimetres (one inch). Franzen said placing granular fertilizer to the side of the seed works best.
Another option for both dormant- and spring-seeded crops is to apply ammonium sulfate or ammonium thiosulfate in solution. Franzen said these liquid fertilizers should not go on the crop until there are at least five true leaves on the plants.
“Leaf burn is reduced at this stage because the plant has been able to develop a waxy protective covering on the leaves.”
The latest research on the breakdown of elemental sulfur shows that the bacterial action required to transform this form of sulfur into plant-available sulfate is less effective than soil scientists previously thought.
“We knew that the transformation doesn’t happen over the winter, but our latest data, based on four years of trials, shows us that it has a hard time happening even through the growing season.
“Soluble sulfate sources are better than elemental sulfur sources, so we don’t recommend elemental sulfur for either a fall or a spring application.”
