Rain showers will be a regular feature this week, creating a window to get fertiliser on grazing swards and silage aftermath.

Where silage was harvested last week, take the opportunity to get slurry on fields to replace nutrient offtake.

Slurry is a great source of potash (K), with moderate phosphorous (P) content, making it ideal for spreading on silage aftermath.

Every tonne of grass harvested in first cut silage removes around 5kg/ha of P (4 units/acre) and 25kg/ha of K (20 units/acre).

Cattle slurry can supply around 9 units/acre of nitrogen, 5 units/acre of P and 32 units/acre of K for every 1,000 gallons/acre applied.

Avoid fertiliser and slurry spreading if heavy rain is forecast as this increases the risk of run off to water courses. Balance crop requirements with chemical fertiliser, depending on soil analysis.

Grazing swards

As slurry is high in potash, avoid spreading or apply at a lower rate (max 1,500 gallons/acre) to swards that will come into the grazing rotation in late June and carry lactating cows.

Potash inhibits magnesium uptake in grass, putting cows at risk for tetany. Make sure cows are properly supplemented with magnesium.

Focus on getting nitrogen on grazing swards with 25 to 30 units/acre in early June to boost growth over the coming weeks. Ideally, choose a nitrogen product with zero K, but with added sulphur.

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