For many years now Teagasc has been advising farmers to spread their slurry in the spring. Although chemical fertiliser costs stabilised this year they still remain at a high level so making the most of their animal slurry remains essential for farmers.
Teagasc estimates that one third of animal slurry in Ireland is spread in the spring. Its research has found that it is in the spring when slurry applications are much more successful in terms of encouraging grass growth. Teagasc has found that applications in the spring have an Nitrogen recovery rate of 25 per cent.
With this being the case it is unfortunate that 60 per cent on animal slurry continues to be applied in the summer/autumn when it is much less effective. Teagasc estimates that results as low as five per cent recovery of Nitrogen has been are the norm in this period.
According to Teagasc, 3,000 gallons/acre of slurry will supply 30 kg N (25 per cent recovery) in the spring but only 6 kg N (five per cent recovery) in the summer/autumn; 20 kg P; and 140 kg K.
Therefore Teagasc estimates 24 kg/ha (19 units/acre) of extra Nitrogen can be captured by switching a 33 m3/ha (3,000 gals/acre) from the summer to the spring. At current fertiliser costs, this could be worth €20/ha (€8/acre) to the farmer.
For many farmers on marginal land the application of slurry in the spring may not be feasible due to poor ground conditions. Wet spring weather particularly in 2011 and 2012 made utilising slurry very difficult.
In a report entitled, Limitations to Spring Application of Cattle Slurry to Grassland in Ireland’ by Teagasc Researchers Stan Lalor and Rogier Schulte of Johnstown Castle. They found that soil trafficability or the ability of soil to support machinery is the main restriction to spring application.
Their research concluded that slurry application methods such as umbilical slurry application can reduce soil compaction and increase soil trafficability, increasing the opportunity for spring application
The research also found that on well- and moderately-drained soils, machines that allow application in swards with higher grass covers, such as the low-emission application methods (bandspreader, trailing shoe and shallow injection), also increase the opportunity for spring application.
This is due to the fact that a greater area of the farm would be available for slurry application on days when soil conditions are suitable, as grass contamination would be reduced.
The prohibited period for the application of slurry will soon come to a close. Click on the image below to see the date of re-opening in your area.
Graph courtesy the Department of Agriculture
