All cereal crops should have a sulphur application every year to avoid the risk of a deficiency of this macronutrient, although 30% of wheat misses out.
Tim Kerr, fertiliser manager with agronomy group Hutchinson, says trial work carried out by his company and fertiliser group Yara showed a significant yield response of about 3t/ha to applying sulphur.
Nitrogen and sulphur as fertilisers work closely together and one major function of the two nutrients is amino acid production. Both elements are required together for this process – but nearly a third of wheat crops receive no sulphur.
The most common current farm practice is for sulphur to be applied with nitrogen – generally with the first or second fertiliser applications in the spring – and Mr Kerr advises farmers to work on a nitrogen-sulphur ratio of 5:1.
For wheat between growth stages 31 and 39, nitrogen uptake averages 2.5 kg/ha a day, while sulphur uptake is on average 0.5 kg/ha a day, and this 5:1 ratio continues further into the season.
Mr Kerr advises milling wheat growers to apply 50kg/ha of SO3 – or, to follow the 5:1 formula, to use 200kg/ha of nitrogen with 40kg/ha of SO3.
He points out that not all sulphur fertilisers are the same and growers should follow the “4Rs” when choosing and applying them.
Mr Kerr suggests growers ask themselves if they are using the right type of fertiliser, are they applying it at the right rate, are they applying it at the right time and, finally, is it going on the right place (ie, accurately).