One of the speakers at Fermanagh Grassland Club recently, has outlined the fertiliser trials he carried out on some farms in Fermanagh.

Guy Benians, a Club member, told his fellow members about the fertiliser trials on local farmers' soils he has run since 2016.

He said three nutrients increased yields: nitrogen (of course), sulphur and sodium, not the usual NPK.

Sulphur was found deficient in Ireland in the 1960's and in Northern Ireland in 1975 and it was, he explained, an essential element to make protein and recently became a component of many compound fertilisers. On sulphur-deficient land one could expect a 40% yield increase by adding 16 kg/ ha sulphur in the form of sulphate with the spring nitrogen. Slurry contains sulphur that will not be available until the soil is warm enough to convert it to sulphate.

However he said sodium was more of a mystery.

"At first it was thought only to increase yields of ryegrass. More types of grass plus broad-leaved plants like white clover are now on a list of species for which sodium is "beneficial," but many others are not helped.

"Nobody yet knows how sodium's beneficial effect works, which has hindered its broad adoption, though Irish fertiliser company, Goulding's, makes "Sweetgrass," a straight nitrogen fertiliser (23% N) with 5% sodium, 2% sulphur and 1.2% magnesium added.

"Research in GB and Northern Ireland suggests that 40 kg/ha is ideal, which 800 kg/ha "Sweetgrass" would deliver, along with twice as much nitrogen as our most intensive farmers use."

So Guy recommends 75 kg/ha of ammonium sulphate and 150 kg/ha sodium nitrate to give 40 N, 40 sodium and 16 sulphur (all kg/ha). Other sources of sodium such as agricultural salt are not as good.

"Our new worry, of course, is carbon emissions," he siad.

This year, with the help of a grant from the Vaughan Trust, Guy is investigating whether sodium is "beneficial" to the multi-species sward John Egerton is growing in the ARCZero project.

He ended his presentation by saying there is further grant money to test other ideas from farmers. Guy works with pot trials which are much cheaper and less risky than for a farmer to commit a whole field to an idea!