For many farmers, once first-cut silage has been harvested, the next step is to get slurry applied to aftermath as soon as possible.

While the nitrogen availability of slurry is lower in a summer dressing compared with a spring application, the amount of phosphate (P) and potash (K) remains fairly constant.

This makes slurry a great fertiliser to replace some of the nutrient offtake in silage.

When it comes to spreading slurry on silage aftermath, outlined are five things to keep in mind.

1. Safety

First off is safety. There may only be a short time window to get slurry out, but do not cut corners when it comes to slurry safety.

Working with slurry can be fatal. When mixing storage tanks, leave the shed as soon as the pump is engaged. Once agitating starts, the release of toxic gas will be at its most potent.

Make sure openings at mixing points are never left uncovered. Keep children and farm pets well clear of such openings.

Take care when travelling on sloped ground with the tanker, especially when turning at headlands and make sure the tractor is big enough to handle the weight of the tanker with a full load.

2. Weather

In an ideal scenario, spread slurry on dull, overcast days, as this reduces the level of atmospheric nitrogen losses. However, this will not always be an option.

At the very least, avoid spreading within 24 hours of heavy rain as there is an increased risk of nutrients being washed out of soils and potentially polluting water courses.

3. Spreading rate

Where silage will be closed off for second cut, go with a slurry application of 2,500 to 3,000 gallons/acre.

This will replace nutrient offtake and feed the next crop of grass. Cattle slurry will supply in the region of five units of P and 20 to 30 units of K per 1,000 gallons applied.

Using a trailing shoe to apply slurry can increase the level of nutrients to the next crop by 20%. If using a splash plate on the tanker, make sure it is turned downwards to direct slurry straight on to grass.

4. Be wary of spreading slurry on paddocks

In contrast, where paddocks have been taken out for silage, be wary of spreading slurry on aftermaths. These paddocks may be needed in two to three weeks time for grazing.

Slurry is high in K, which inhibits plant uptake of magnesium. This puts lactating cows at greater risk of taking grass tetany, as regrowth will be lush, highly digestible grass. Therefore, avoid spreading slurry on paddocks grazed by cows.

If stores are being grazed and it will be at least three weeks before cut paddocks come back in the rotation, there is a window for slurry.

But even then, go at a reduced rate of 1,500 to 2,000 gallons/acre of very watery slurry.

5. Leave a gap between slurry and chemical fertiliser applications

After applying slurry to silage aftermaths, leave a gap of at least one week before dressing swards with chemical fertiliser for second cut. This will make far greater use of the two nitrogen applications.

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