Published by Farmers Guide, July 2009

Fertiliser treatment gives
crops a boost

Jake Sanders of SFP (left) and Tim Kerr of Carrs Fertilisers were promoting the new phosphorous fertiliser enhancer Avail at Cereals 2009.

IF YOU take the fertiliser recommendations in RB209 for granted you could be missing a trick, according to Tim Kerr, of Carlisle-based Carrs Fertilisers.
“In most soils, very little of the phosphate fertiliser applied to the soil will ever reach the crop,” he said. “Research has shown that 75-95% of the phosphate will be locked up in the soil during the year of application and will be unavailable to the growing plants.”
The reason is quite simple, in chemical terms phosphate has a negative charge, while many of the elements found naturally in soil – including calcium, iron, magnesium and aluminium – have a positive charge. These elements are attracted to the phosphate and create insoluble compounds that are unavailable to any roots in the vicinity.
The answer, you might think, would be to increase the P content in fertilisers, but according to Mr Kerr that wouldn’t be viable.
“Years of trial have shown that increasing the phosphate content in a fertiliser further does not give sufficient yield response to make it economically viable,” he said. “In other words, the current RB209 recommendations give the most economic return based on conventional agronomic practice.”
But that’s not the end of the story. Aware of the problems of phosphate being locked-up in the soil, and the fact that crops respond extremely well to additional free phosphate, scientists at the United States-based research and development company SFP began looking for a way to get around the problem. And the result is the phosphate fertiliser enhancer Avail.
“What we found was that we could create a coating for the phosphate that can protect it from the positive ions that would normally combine with it to produce compounds like calcium phosphate that are unavailable to the crop,” SFP vice-president of market development Jake Sanders said. “The Avail coating creates a shield effect around every granule of phosphate fertiliser that keeps the positive ions away, but allows roots to come into contact with the fertiliser and pick up valuable nutrients.”
From a purely scientific viewpoint you would expect this treatment to improve yields, and that’s exactly what field trials both here and in the US have found.
“By inhibiting the fixation of phosphate fertiliser and promoting the availability of phosphorous by using Avail, we have been able to show yield increases of 10-15% compared to using untreated fertiliser,” Mr Sanders said. “The product works in any crop, in any soil and in any climate, and has been providing an excellent return on investment.
“Potatoes is an excellent example, with Avail enhancing both the quality and quantity of the crop harvested, indeed the University of Idaho now recommends the product for use on every crop.”
After five years of development, Avail was first sold on the west coast of the US in 2003, and was made available across the whole country in 2005. It made its first appearance in the UK at the 2008 Cereals Event, and was back this year with Carrs Fertilisers in place as official distributor.
“Carrs got involved after Cereals 2008, and I joined the firm shortly after to lead the marketing of the product here in the UK,” Tim Kerr said. “Unless you’re using liquid fertiliser, Avail has to be added to the phosphate fertiliser granules before the blending stage, so it made sense for SFP to appoint a blender to distribute the product.
“With blending plants at Carlisle and in Scotland, we will be supplying Avail-treated compound fertilisers throughout Great Britain.”
Mr Kerr added that the Carlisle plant had haulage deals in place that allowed Carrs to supply fertilisers to customers throughout England at same price as locally sourced supplies – plus, of course, the cost of the Avail, which is about 20p for each kilo of phosphate treated.
“We have hauliers across the UK that will deliver our fertilisers wherever it needs to go,” he said, “so supply will not be a problem.
“We feel it’s extremely important in the early stages to keep a firm control over the quality of the Avail-treated fertiliser being supplied, but if the product takes off the way we expect we could well install the application equipment at other blenders’ plants in the future.”
Carrs has been officially supplying Avail-treated phosphate fertilisers since Christmas and has already sold more than 10,000t.
“The product works and gives growers and their agronomists another option when they are making their fertiliser choices,” Mr Kerr said. “They can use Avail to cut costs by reducing the amount of phosphate fertiliser they apply, or they can aim for the increased yields that result from the extra available phosphate in the soil at standard application rates.
“Either way, the product will ensure they make much more efficient use of their investment in fertiliser, as well as addressing the plant health and crop quality issues that can result from having too little available phosphorous in the soil.”