Slurry is a valuable source of nutrients on farms, and using it correctly can have significant benefits to soil health and fertility.
When the cow eats grass, or it is harvested for silage, nutrients are removed (N), phosphorus (P), and potassium (K).
After being eaten by the cow, nutrients are excreted onto the land or into tanks on farms in the form of slurry – making this a valuable fertiliser source on farms.
The figure generally used by Teagasc, is slurry has a value of 9-5-32/1,000 gallons, but there is great variation between farms and even tanks on farms.
With the average for Teagasc/Dairygold suppliers based on research outlined at the dairy conference being 10.7-5.3-27.
Covered tanks on this farms averaged 11.9-5.9-29, while open tanks averaged 7.8-4.1-23.
During the national dairy conference it was highlighted that without the correct storage facilities on farms, the full value of these nutrients is lost.
Pat Tuohy, Teagasc Moorepark, explained that when using storage requires of 20 weeks, a cow would produce 1,452 gallons of slurry.
Spread in the correct conditions it has a value/cow of €64, while spread in the wrong conditions has a value of €21/cow.
It is important to note that this is slurry spread in perfect conditions on land that requires it vs on being spread in very poor conditions and on land that doesn’t require it.
Slurry
Speaking during the workshop at the national dairy conference, Pat Tuohy from Teagasc said that maximising slurry nutrient use efficiency will help to maintain grass production levels in the face of reductions in chemical fertiliser application limits.
But noted that sub-optimal management of slurry also represents a significant treat to water quality.
He said that we must ensure that application timings, locations and rates are optimised by considering storage capacity, management strategies, nutrient use efficiency and identify other opportunities to add value to slurry.
As we face into further reductions in chemical nitrogen (N) allowances due to environmental regulation the value of our slurry increases.
In the past slurry has always been compared to the cost of chemical fertiliser.
However going forward farmers need to look at the value of our slurry and its ability to grow grass in the absence of chemical fertiliser.
In the past if we didn’t get the maximum value from our slurry by spreading at the wrong time or weather conditions. But we could supplement our grass growth by top dressing with chemical N.
This also potentially created water quality issues based on spreading at the right time.
It was noted by Tuohy that as we can see by spreading at optimal times it is worth an additional €43/cow by using the nutrients to grow grass.
This will have a knock on effect of improved water quality while maintaining grass growth.