How soil sampling helps with fall fertilizer

Producers looking to apply fall fertilizer should pull soil samples this fall

Although many producers across Manitoba are busy with harvest, they should also keep soil sampling top of mind.

John Heard is a soil and fertility extension specialist with Manitoba Agriculture and Resource Development. Historically, industry experts advised farmers to wait until soil temperatures drop to 5 C (41 F) to soil sample for nitrogen (N), but early sampling offers benefits, said Heard.

“Between 45 and 50 per cent of farmers in Manitoba still try to put down their N in the fall. So, soil sampling in the fall is important for them to choose the rates they want to put down,” he told Farms.com.

Since N rates stay stable throughout the winter in Canada, fall soil testing allows farmers to have a good understanding of what nutrients will carry over to the spring. The best time to pull soil samples depends on the crop.

“Crops like peas or even canola tend to see nitrogen levels creep up or continue to increase through the fall. Given a choice, farmers would probably want to sample later in the season so it can capture the nitrogen levels that will be there,” he said. Producers can pull soil samples from cereal fields now.

Through soil sampling, farmers can also gain information about the other nutrients in their soil.

“Soil tests offer a lot of nice-to-know information, but the need-to-know information usually is the nitrogen, phosphorus, potassium and possibly sulfur,” said Heard.

Farmers interested in soil sampling should work with their agronomists or crop advisers. These individuals can also help producers tailor their fertilizer programs, said Heard.

“A portion of farmers do variable rate or zone management of fields and that (management strategy) requires specialized computer equipment to guide them to their sample spots in the fall,” he said. Consultants or advisers can assist.

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