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Floating your fall fertilizer

With new fertilizer products on the market and new machinery available,
 fall-applied fertilizer could be your solution

At first glance the Case 4530 is a strange-looking contraption. It seems to be an awkward combination of a sprayer and a tractor. As it turns out, the “floater,” as it’s commonly called, is anything but awkward. Rather, its 70-foot boom and latest and greatest GPS make it well suited for the job it was designed to do — surface apply, or “float” granular fertilizer and chemical.

Dean Schenk, agronomist with Precision Ag Services in southeastern Saskatchewan, has conducted extensive testing to ensure that surface fall applied fertilizer ends up in the soil ready to grow a crop. “With the trials and tests we have done we are confident that it works,” said Schenk, “and it can be suitably applied to any crop.”

Urease inhibitors

Advancements in product technology, specifically urease inhibitors, are a big reason fall application of fertilizer is viable.

Urease enzymes help break down urea and change it to ammonia. Through the process of hydrolysis a hydrogen ion in consumed — increasing the pH of the soil around the urea. Nitrogen in the soil moves towards ammonia at high pH levels, and putting shallow banded or surface applied urea at risk of loss through volatization.

If volitization occurs, 30 to 50 per cent of the nitrogen could be lost as ammonia escapes through the porous layer of topsoil. There are two solutions to preventing or at least lowering volitization. One is to place the urea two inches deep in the soil. The other solution is to surface apply nitrogen with a urease inhibitor.

Urease inhibitors slow the rate of hydrolysis, preventing the pH spike that increases volitization. When a urease inhibitor is used, nitrogen losses can be minimized to 10 per cent. Delaying hydrolysis also provides time for moisture to move the urea down into the soil, which will guard against the movement of ammonia into the atmosphere.

“New advancements in products stop the gassing off of nitrogen, and give about 30 days protection, helping us have a more efficient product,” says Schenk.

“Urease inhibitors are an insurance policy on the fertilizer investment. When we factor in the amount we could potentially lose with the untreated urea (50 per cent) as compared to the inhibitor treated urea (10 per cent) the cost of treating it becomes minimal compared to the cost of not treating it.”

The Case 4530 is commonly called a “floater.” It has a 70-foot boom for surface application of granular fertilizer and chemical.
The Case 4530 is commonly called a “floater.” It has a 70-foot boom for surface application of granular fertilizer and chemical. photo: Danell van Staveren

Along with advanced urease inhibitors, there are other, more practical reasons to apply fertilizer in the fall. Fertilizer prices are generally cheaper in the fall than in the spring. Schenk says the company floating the fertilizer will have more time to do the job in the fall than in the spring during the rush of seeding. Product can be applied late into the fall, even with up to four inches of snow.

“It pencils out well to guys with the per-acre fee. The prices in fall are better, and they are storing fertilizer in the ground rather than needing bin space for it,” says Schenk. “It made life easier for the farmer, but created another busy season for us. But what we get done in the fall we don’t have to do in the spring.”

Fall application frees up time and manpower in the spring. When nitrogen and sulphur are applied in the fall, only phosphate and potash need be applied in the spring, which means hauling less product to the field and less stop time for filling during seeding. “Guys can cover more acres in the spring with less fills,” says Schenk. “Spring seeding works well when nitrogen and sulphur are eliminated in the fall.”

The downsides to fall-applying fertilizer are few, says Schenk. There is the chance that urea will be lost. In the event of spring flooding, the product could become mobile and be washed away. Some of the acres that are accessible in the fall may be too wet to seed in the spring, causing product to be lost.

Schenk sums fall application up like this: “Fall-applied fertilizer opens up a lot of opportunities on fertility to do a better job of soil fertility. It is also very economical when all the numbers are worked out — wages, time, fertilizer.”

In the fall of 2013, Schenk and Precision Ag Services floated roughly 15,000 acres. In the fall of 2014, they want to exceed that number. Like any tractor or sprayer working in the field, they hope to make their strange-looking contraption a common sight.

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