The benefits of adding sulphur to a spring nutrition programme shouldn’t be forgotten, especially this year as growers seek to improve nitrogen efficacy.

While many have prioritised securing a supply of straight N when prices began to rise, there remains still the opportunity to incorporate sulphur into a fertiliser programme to add valuable nutrition to this year’s crops.

“Sulphur is an essential nutrient that is key for protein formation and has a direct influence on improving crop quality,” pointed out Tom Oates, a nutrition agronomist with Origin Fertilisers.

“Crops with high N inputs tend to have increased sulphur requirements, as sulphur helps plants use that N more effectively. For most cereals and grass, farmers should be looking to apply 12kg of N to 1kg of S to maximise nitrogen uptake and crop performance, and 6kg of N to 1kg of S for OSR and other brassicas.”

For those who have not yet purchased sufficient supplies of sulphur to support crop growth, Polysulphate – which is mined in the UK – could be a versatile and valuable source as it contains no additional N.

With the analysis 48% SO3, 14% K20, 17% CaO, 6% MgO, it could provide crops with their entire sulphur requirements. Since the sulphur in Polysulphate has a prolonged release pattern, growers can apply the product in early spring without the need to ‘top up’ later in the season, Mr Oates explained.

“The sulphur in straight ammonium sulphate is released over five days, so is vulnerable to leaching if there is heavy rainfall following application, particularly on sandy soil. The sulphur in Polysulphate is released over 55 days and so there is a much lower leaching risk, and more sulphur is likely to be taken up by the crop.

“An early application of 100kg/ha of Polysulphate would supply around 48kg of sulphur (as SO3) to the growing crop over the course of the season, enough for most cereal crops, according to RB209. Average sulphur applications tend to be at the upper end of RB209 recommendations or higher, and growers will see benefits of applying extra sulphur to the crop," he said.

“It also supplies a small amount of readily available potassium, which is useful if farmers have cut back on their usual autumn applications. Small quantities of calcium and magnesium are also included in Polysulphate,” he concluded.

Crop Sulphur requirement*

Cereals 25-50kg SO3/ha

OSR 50-75kg SO3/ha

Legumes/sugar beet 25kg SO3/ha

Silage 40kg SO3/ha before every cut

*Example of crop requirements according to RB209