How soil tests can help avoid the fertilizer guessing game

Soil tests

“Don’t guess; soil test,” urges University of Saskatchewan soil science professor Jeff Schoenau.

These tests tell farmers the available nutrient status of their soils, and are a key component to determining fertilizer needs and appropriate rates of application, he says.

“Nitrogen and sulphur can vary a lot from year to year, field to field, and location to location within fields,” says Cory Willness, president of CropPro Consulting. “Give your fertilizer dollars a greater opportunity to grow more grain and improve your soils.”

Some farmers might have been better off conducting their soil tests at the end of 2017’s growing season than starting now, according to Manitoba Agriculture crop nutrition specialist John Heard.

“That way there was ample time to design economic and environmentally effective fertility programs,” he says.

Also, spring testing on still-frozen soils might provide incomplete nutrient reserves data, Heard adds.

Annual testing

Although phosphorus, potassium and salinity don’t usually change much year to year due to crop removal or nutrient additions, University of Manitoba’s Don Flaten still recommends they be tested every year.

“These measurements can change moderately due to effects of moisture and temperature, or substantially with the addition of livestock manure,” Flaten says. “Long-term annual testing can also help to identify trends in these measurements.”