Spring grass may be lacking in a key element – But it’s not N, P or K

Sulphur is an essential nutrient for grass growth, but it tends to be ignored by grassland managers, according to John Bailey of AFBI (Agri-Food and Biosciences Institute).

“Under supplying Sulphur can result in sizable grass yield losses. When grass becomes Sulphur deficient both the herbage yield and quality suffer,” he said.

Bailey spoke at the recent Fertiliser Association of Ireland Spring meeting, where he said that soils lacking in Sulphur can cause a number of problems for farmers.

Soils that are low in Sulphur can stop grass plants from using Nitrogen, which causes the lower leaves of the plant to turn light green or yellow and reduce overall yield, he said.

He also said that the protein content of the grass decreases and some farmers may have to purchase expensive concentrates to supplement cows diets.

Sulphur-deficient diets can result in slower growth rates, lower milk yields and reduced feed efficiency.

Dealing with a Sulphur deficiency

Bailey said that Sulphur deficiency tends to be higher in April and May and as a result it is has a big impact on first cut silage yields.

To address this issue, he recommended that farmers spread an artificial Sulphur fertiliser early in the year.

“In the last few decades the Sulphur availability to crops has declined across Ireland.

“Sulphur should be applied to all grassland in the spring at a rate of 12-14kg/ha to eliminate the risk of deficiency throughout the year.”

The AFBI representative also said that slurry and farm yard manure contains large volumes of Sulphur, but it is present in a form that is unavailable to the grass plant.

Farmers cannot rely on slurry alone to address a Sulphur deficiency and an artificial fertiliser should be used to address this issue.

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