Phosphate fertiliser could render urease inhibitors ineffective
© Tim Scrivener There are potential concerns over Defra’s urea inhibitor fertiliser rules due to a incompatibility of phosphate fertiliser with the majority of urease inhibitors, which could render inhibitors ineffective.
Origin Fertilisers technical director Peter Scott notes that some inhibitors currently on the market are incompatible with phosphate- a problem going unnoticed within the industry.
“The main family of urease inhibitors are phosphoric triamides, such as NBPT, and they have a strong incompatibility with phosphate,” says Peter.
“The high acidity of phosphate reacts with the inhibitor and breaks it down.”
See also: Urea inhibitors to be a ‘requirement’ from 1 April in England
“Independent trial data revealed a full rate of inhibitor blended with a NPK fertiliser reduced inhibitor efficacy to zero just a few days post-application,” says Peter.
“This not only leads to reduced crop performance, but brings environmental issues as well.”
Not practical on farm level
However, Luke Pollard, campaign manager at BASF said the issue is not practical at the farm level.
“Although it is correct that there are multiple studies showing that the efficacy of some urease inhibitors is decreased when used in a blend with phosphate, this is practically not an issue at all at the farm level,” he says.
Luke goes on to say: “Physical blends of protected urea and other minerals can require specific attention, and there are several easy to implement technical solutions available which maintains stability of the inhibitor.”
Alternative inhibitor
Peter highlights an alternative urease inhibitor which offers phosphate compatibility with comparative performance and price to other inhibitors.
Peter says: “If growers want a NPK urea blend, we are not selling NBPT-type inhibitors. Instead, we are offering the Nutrisphere alternative, which is available for the same price and is compatible with phosphate.”
It offers a completely different chemistry- formed of two organic acids, maleic acid and itaconic acid, which are derived from fermented maize starch.
Urea inhibitor rules are already in play
As of 31 March, untreated urea is prohibited from use.
Uninhibited urea can only be used from 15 January to 31 March.
The new rules apply to England and affect any fertiliser that contains 1% or more of urea.
Compliance will be overseen by Red Tractor, with farm inspections including records of responsible fertiliser use.
