Controlled-Release Foliar Nitrogen

Posted in: Farming     

A product commercially in use for the past 15 years in the US is now available to Canadian farmers.

This unique CRN technology was developed in the mid-1980s and Yara has been marketing it in countries outside the US under a license agreement with Helena Chemical Company, a US-based company.

Last-N is a controlled-release foliar nitrogen that’s a complex mixture of more than 150 different combination products between urea and methlyene urea. These compounds produce a uniform water-soluble concentrate. Last-N is chemically and physically distinct from simple urea and ammonia-based fertilizers, as well as other foliar nitrogen products now entering the market place.

“The product has a resinous base that releases nitrogen consistently and dependably to the plant over a wide range of conditions. In cool weather, it releases over time to give an extended and controlled nitrogen feeding,” says Robert Collaer with Yara North America Inc.

It’s a product that has been thoroughly researched since the technology was patented in 1986. It has been extensively researched, published and endorsed by 14 university coauthors. No other foliar controlled-release nitrogen product has this level of research, or history of performance, which is why Yara can confidently represent it on a global basis.

While soil applied urea will typically be completely converted to nitrate nitrogen within two weeks of a spring application, complete conversion of foliar applied Last-N to nitrate nitrogen may take up to 10 weeks, providing a controlled-release effect.

“There are multiple formulations of this technology on the market in the United States. We chose Last-N 25-0-0 with 25% SRN specifically for our Canadian conditions, because its performance characteristics match the conditions we typically find in the prairies. With warm days, cool nights and a short growing season available, Last-N is designed for our conditions,” says Collaer.

Last-N is designed to help farmers balance foliar and soil nitrogen fertility to maximize their profitability. If a grower begins with a standard fertility program, he now has the option to fine tune his nitrogen program during the growing season by applying Last-N.

06 0709 Controlled Release (1)“What many farmers are doing in the northern states is managing their nitrogen program for normal conditions because they don’t want to apply more nitrogen than they potentially need. When the time comes to make the extra yield potential decision, if it’s a go, they apply Last-N,” he says.

Because foliar applications are often best timed to coincide with pesticide application, Last-N has been tested and found to be physically compatible with most fungicides and insecticides at various water rates.

Yara’s website – – provides information on various tank mixes performed with Last-N. Some of the more common tank mixes are with cereal fungicide applications.

Collaer says researchers have often found improved plant protection activity when tank mixes containing Last-N are applied, compared to applying pesticides independently. Many US basic manufacturers co-endorse its use in tank mixes with their products.

“There isn’t a significant runoff factor with Last-N because it’s a foliar product used at low application rates. It is formulated not to dry in a crystalline form on the leaf. It stayswet quite a while and almost looks like a resin on the plant leaves. Because of these unique characteristics, we see high crop safety with minimum potential for leaf burn, while also having extended nutrient release even after it starts to dry,” says Collaer.

Last-N has a much lower leaf burn potential than other liquid nitrogen products, which Collaer says is an important advantage.

In Canada, Collaer expects the most common crop uses will be on cereals, canola, corn and potatoes.

In all cases, Last-N can be applied either undiluted or diluted with water for aerial or ground application. Use sufficient carrier to adequately cover crop foliage.

Yara is the largest fertilizer company in the world.

For more information contact please contact your local Ag Chem dealer.

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