GHGMP News Releases

Soil test is good investment for optimizing yields

Indian Head, Sask. October 12, 2004

Regular soil testing can make the difference between a good crop and a great crop, say Saskatchewan soil conservation specialists.

A nutrient analysis can't guarantee top yields, but it lets Prairie producers know the crop has not only the right nutrients, but the proper nutrient balance to make the best use of moisture and temperature in any growing season. A proper nutrient balance also benefits the environment.

The soil testing message isn't new, but it bears repeating, say specialists. With growing awareness and in some respects, increasing pressure to better balance soil nutrients with crop needs, the initial late fall or early spring soil test is an important step to prevent over or under fertilizing the crop.

"Probably the greatest risk of not soil testing is missing out on potential crop yield," says Tim Nerbas, a soil conservation agrologist with the Saskatchewan Soil Conservation Association (SSCA) based in North Battleford, Sask. "Without the soil test, producers run the risk of not achieving a nutrient balance. If one of the key nutrients or micronutrients is missing, the crop isn't able to make full use of the available nutrients." Whatever is missing becomes the limiting factor for potential yield.

Balanced fertility has several benefits, he notes. It helps optimize crop yields, which means producers are getting the best value from their fertilizer dollars. After a dry year some residual nutrients can remain in the soil following harvest. If moisture conditions improve, surplus nitrogen, for instance, can be leached below the rooting depth, or lost as a harmful greenhouse gas such as nitrous oxide through the process of denitrification. Thus annual soil tests are an important tool to not only determine what residual nutrients remain in the soil, but for setting realistic yields goals.

Different approaches can be used to balance crop nutrients, says Rich Szwydky, of Borden, an SSCA agrologist for west central Saskatchewan. Szwydky developed a couple demonstration projects in 2003 funded jointly by SSCA and the federal Greenhouse Gas Mitigation Program for Canadian Agriculture (GHGMP). Versions of the demonstrations continued through the 2004 growing season.

One project near Kindersley looked at a split application nitrogen treatment applied post-emergent. Some nitrogen was put down with the seed and the balance was applied in-crop with two different liquid application methods.

The other project looked at the effectiveness of delayed-release nitrogen fertilizer. This is conventional urea or UAN solutions treated with Agrotain, an additive that delays the release of nitrogen. The potential value in this is that higher rates of fertilizer can be applied at seeding with reduced risk of seedling damage and minimum nitrogen losses.

Both projects started with a soil test to determine additional nutrient requirements of crops, says Szwydky. For details on the demonstration visit the SCCC Website at

"Split applications of nitrogen gives producers greater flexibility in their fertilizer program," says Szwydky. "This practice minimizes the risk of placing all the nitrogen at the time of seeding, especially in drier soils. Also, by providing nitrogen to meet the changing demands of a growing crop, producers can potentially increase nitrogen-use efficiency.

The delayed-release nitrogen demonstration showed improved crop safety with fertilizers and improved nutrient uptake, he says. Agrotain is an additive to urea or UAN solutions. It temporarily inhibits the activity of the naturally found urease enzyme in the soil. The urease enzyme is needed to convert the urea fertilizer into ammonia, therefore reducing volatility losses especially for surface applied nitrogen. It was developed primarily to reduce nitrogen losses in broadcast or surface applied fertilizer, but works with banded fertilizer, as well.

Results from 2004 demonstration projects will be known later this year.

For more information, contact:

Tim Nerbas, PAg, SSCA Agrologist
North Battleford, Sask.
Phone: (306) 446-7982

Rich Szwydky, PAg, SSCA Agrologist
Borden, Sask.
Phone: (306) 997-6269

Doug McKell, Executive Director
Soil Conservation Council of Canada
Indian Head, Sask.
Phone: (306) 695-4212