The importance of slurry testing was highlighted at the recent ‘Getting the Best Out of Slurry‘ webinar held by Teagasc.

Fertiliser prices in 2022 have led to a growing concern within the sector, with more efficient use of slurry being seen as a way of offsetting fertiliser usage.

As the slurry season opens on farms, Teagasc is advising farmers to test their slurry. This will give farmers an accurate nutrient value for their slurry.

The nutrient value of slurry can differ greatly from farm to farm, depending on the system being operated, how much water has gotten into the tank, along with several other factors.

Along with soil sampling, this will give you a more accurate picture of the fields that require slurry and whether or not your fertiliser bill can be reduced.

Slurry testing

To get your slurry tested farmers have two options; the first option is to send a sample to the lab for testing.

This is done by collecting about 1L of slurry and sending it to be tested. If you have a number of tanks you can combine the samples. The same labs that do soil testing will also test your slurry.

The second option is to buy a hydrometer, which means you can then test your own slurry on the farm.

This is a quicker way of determining the value of your slurry. A hydrometer works by determining the dry matter (DM) of the sample. The DM matter can then be used to determine the nutrient value

The test will determine the amount of nitrogen (N), phosphorus (P) and potassium (K) that the slurry contains.

N kg/m3
(units/1,000 gallons)
P kg/m3
(units/1,000 gallons)
K kg/m3
(units/1,000 gallons)
20.4 (4)0.21 (2)1.4 (13)
40.7 (6)0.35 (3)2.3 (21)
61.0 (9)0.5 (5)3.5 (32)
71.1 (10)0.6 (6)4.0 (36)
The effect of slurry DM on the N, P and K values of cattle slurry
Table source: Teagasc

The result will mean that you have a better understanding of what is actually in your slurry.

When your slurry is then used more effectively, you can save on chemical fertiliser use.