Slurry is valuable but slurry gas is dangerous

CATTLE slurry from covered slatted tanks is a valuable source of nutrients for the land and slurry can reduce the fertiliser bill if used properly and at the right time. However, farmers need to be ever-vigilant to the dangers associated with slurry.

Slurry can be applied to grassland from 16th January onwards, provided conditions are suitable. 1000gls of undiluted cattle slurry has a nutrient equivalent of 9 units of Nitrogen (N), 6 units of Phosphate (P), and 38 units of Potash (K).

The best time to apply slurry is from late January to April. On heavy land it may be necessary to delay spreading until after the first cut of silage. Based on the nutrients in the slurry, each 1,000 gals of undiluted slurry is worth about €30. Slurry should always be applied where possible to a bare field or fields with low grass cover. Do not apply slurry to frozen or waterlogged fields as there would be a huge risk of nutrient runoff.

This only results in major pollution problems and great economic loss to the farmer.

Care is needed when handling slurry. Cattle slurry is a mixture of solids, liquids and gases, which can be lethal.

These gases are generated continuously in the slurry and when the slurry is agitated the gases are released very quickly. If silage effluent has been mixed with the slurry there usually is much more gas produced. The most dangerous gas is hydrogen sulphide which is extremely poisonous to animals and humans. Low levels of hydrogen sulphide smells like rotten eggs but any substantial level dulls the sense of smell altogether, which means a person can be in lethal danger but entirely aware of the risk. If exposed to high levels of hydrogen sulphide death can occur within minutes.

Recommendations for agitation

1. Take all animals out of the shed

2. Open all doors and have another adult with you

3. Stay out of the shed for at least 30 minutes after agitation.

4. Don't enter the shed or tank without proper breathing gear.

5. If agitation is not complete within one hour extra water may need to be added to get the slurry suitable but this adds to the cost of spreading. However, watery slurry is more easily washed into the soil and can be applied to grassy fields.

Recommended amounts

Slurry can be spread with a vacuum tank or via the umbilical hose system.

Care should be taken to get an even spread. Normal rates of application are 2000-4000 gals per acre.

Slurry should be mainly spread on silage ground.