A new urea product is said to cut leaching losses, which could lead to a reduction in overall costs. Louise Impey sees if the claim stacks up

Bridging the gap between ammonium nitrate and urea is how a new generation stabilised urea product is being described by Gleadell, the company behind its UK introduction.

Alzon 46 contains urea with nitrification inhibitors, explains Gleadell fertiliser manager Calum Findlay, which works by lowering the conversion rate of ammonium to nitrate, so that the nitrate is released slowly.

That reduces the volatilisation and leaching losses associated with alternative sources of nitrogen, he claims, leading to more efficient use of the nutrient and cutting the number of passes required.

“The effect of the nitrification inhibitors can last from four to 12 weeks,” he says.

“This means that more fertiliser can be applied at one time, without any concerns about the environmental implications of using higher rates or that a dry spell will cause big losses from volatilisation,” Mr Findlay adds.

It should also increase fertiliser efficiency, he predicts, paving the way for growers to reduce rates without sacrificing yield.

Mr Findlay stresses that nitrification inhibitors are different to urease inhibitors, which are found in other urea products.

“Urease inhibitors work by delaying the conversion of urea to ammonium and tend to last for up to three weeks. But they don’t slow the production of nitrates,” he says.

Alzon 46 was developed specifically for the cooler north European climate by German group, SKW Piesteritz, which incorporates the inhibitors into the granules during the manufacturing process.

Results look promising in Essex and Staffs

Essex grower Chris Evans has used Alzon 46 for the past two years, substituting the product for straight urea on both barley and maize.

He has reduced the number of passes in cereal crops from three to two, immediately negating the price differential, and is much happier using a more environmentally friendly urea product.

“There’s minimal nitrification and leaching with a stabilised urea product. That’s very relevant here as we are in the Lee Valley Regional Park Authority, an important catchment area,” he says

His positive experience to date with the product has encouraged him to try using reduced rates in 2014, with the intention of cutting the rate by 20%.

“We are farming on fairly fertile soils and trial results have suggested that this approach should work. There’s less wastage as the nitrate is released over a period of time,” he adds.

Using a 46% nitrogen source also has advantages, points out Mr Evans. “We make fewer journeys, which helps with the land that is away from the farm base. And Alzon 46 has a very good spreading pattern – we are applying it up to 24m with great accuracy,” he says.

The £10-15/t premium over straight urea isn’t a concern.

“We recouped that straight away by reducing our workload and the number of applications,” Mr Evans concludes.

Staffordshire grower Ray Bower tried the product in 2013, replacing his usual second and third dressings on winter wheat.

He believes it performed as well as ammonium nitrate, while saving him one pass and working out to be cheaper, and is planning to use the product again.

“I stuck to straight urea for the first dressing, applying it at the beginning of March,” he recalls.

“The Alzon 46 then went on in one hit at the end of April, as it has an extended period of use. Yields were maintained, so the nitrate must have been available when required.” Bower adds.

It represents a 5% cost saving (£11/ha) over ammonium nitrate, calculates Mr Findlay, but commands a premium of around £17/ha over standard urea.

It also contains 46% nitrogen, some 115kg more nitrogen a tonne than ammonium nitrate, which has storage and handling benefits, as well as work rate implications, he adds.

Trials conducted by crop consultants NIAB TAG in both wheat and oilseed rape have shown slight yield benefits, confirms the organisation’s Nick Watson.

“After just one year of trials, it’s difficult to say whether a stabilised urea product has any benefits over straight urea. But we’ve certainly seen hints of them,” he says.

Being able to apply a single dose of Alzon 46 early in the season is an advantage on many farms, although the yield increases recorded this year weren’t significant, he points out.

“That’s why it’s important that this type of work is conducted over a number of growing seasons, across different conditions, so that growers have more information on which to base their purchasing decisions,” he adds.