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The true value of slurry

Did you know? Did you know?19-11-2019
Afbeelding: Slurry Store

Utilising more slurry should be considered, but only if its nutrient value has been measured. Slurry is a good source of nitrogen (N), phosphorus (P) and potassium (K), but any losses during storage need to be considered. 

If purchasing fertiliser, 50kg of a 5-5-30 fertiliser would be equivalent to 4.5m3 of slurry. The time of year that slurry is applied can affect its nitrogen value. Slurry applied in summer, or in dry and hot conditions, will reduce N value by 1.5kg/4.5m³. But P and K values are not affected. It is important to remember that a slurry might equal 50kg of 5-5- 30 in the spring, but it could be 2-5-30 in the summer. 

Slurry with a thick consistency, and has not had rainwater or yard washings added, will typically be between 6% and 8% dry matter (solids). If diluted, the P and K will be also be diluted as will the fertiliser value. So, where slurry is between 3% and 4% dry matter (more watery), the value of 4.5m³ will be reduced to be equivalent of 50kg of 5-3-15 in terms of N, P and K.

A 30% dry matter silage crop will remove 2.1kg of P and 7.2kg of K per tonne of fresh grass. So targeting slurry on silage ground makes good sense. But slurry is not ideally balanced in terms of P and K for grazing, because typically more K will be applied than is required. 

Analysing your slurry before utilising it will assess its value, as well as reviewing your total fertiliser requirements. Treating your slurry with a bacteria treatment during storage can also help reduce N losses by up to 50%.

For more information

For more details please contact your local account manager or call our forage team on: 0330 678 1200