Although the spring rainfall across Scotland hasn’t been a surprise to many farmers, the prolonged wet weather since August last year will mean farmers may need to replenish soil nutrient levels to avoid them becoming precariously low.
Essential primary and secondary nutrients including nitrogen, potassium, sulphur and sodium, along with calcium and magnesium, may be depleted within the soil profile and offer limited plant availability. A key nutrient among these is sulphur, as its relationship with nitrogen is integral to maximising nitrogen use efficiency.
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Nutrition Agronomist Julia Andrews
Julia Andrews, a nutrition agronomist covering Scotland for Origin Fertilisers, says maintaining sulphur reserves throughout the season is essential if silage quality and yield expectations are to be met.
“Sulphur’s importance to both yield and quality has been proven, meaning farmers should be considering it in their nutrition plans at the start and following each cut. Sulphur helps plants use nitrogen more efficiently and if crops have a high nitrogen requirement, then they tend to require a high sulphur input.”
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Declining trend
A worrying development over recent years is, according to data from the British Survey of Fertiliser Practice (BSFP), that sulphur applications to silage grassland across Scotland appear to be in decline.
The data shows that in 2021, sulphur applications of 25kg/ha or above were applied to 28% of silage grassland. However, this figure has dropped significantly in 2022 to just 13%.
Of greater concern are fields that have received no sulphur applications. In 2021, 64% of silage ground had no sulphur applied, whereas this figure shot up to 79% in 2022, with only 4% of the fields surveyed receiving a pass of above 50kg/ha.
Polysulphate
Julia explains why this is a concern: “We used to rely on atmospheric sulphur to feed crops, but this form of sulphur hasn’t been dependable for several decades and has reinforced the need for additional sulphur fertiliser. Sulphur is highly mobile in the soil, so applications need to be made every year at regular intervals to ensure we feed the plant that feeds the animal.
“The steady drop in sulphur applications could be down to a variety of reasons, but if you’re purchasing nitrogen for grassland or arable crops, then you should be purchasing sulphur as well.”
Sulphur benefits
Polysulphate is naturally mined in Great Britain and provides immediate and sustained release for up to 55 days.
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