Getting the most from your Slurry in 2022
Type Media Article
Mary Roache, ASSAP advisor, Teagasc Westport
With fertiliser prices at an all- time high cattle slurry will be a key resource on farms to reduce costs in 2022. However, it must be utilised efficiently and any losses prevented. The prohibited period when slurry and fertilisers are not allowed to be spread on Mayo farms ends on January 15th. However, even after this date slurry should not be applied in the following instances
- The land is waterlogged;
- The land is flooded, or it is likely to flood;
- The land is frozen, or covered with snow;
- Heavy rain is forecast within 48 hours
- You must not use an upward-facing splash plate or sludge irrigator on a tanker or umbilical system for spreading organic fertiliser or soiled water.
- You must not spread organic fertilisers or soiled water from a road or passageway, even if the road or passageway is on your own holding.
Remember that a minimum buffer zone of 5m must be kept back from all drains even those which are dry. *The 5 metre buffer zone is increased to 10 metres for a period of two weeks preceding and two weeks following the periods when application of fertilisers to land is prohibited.
The best response to slurry application is achieved when the soil temperature is above 6 degrees and the grass is actively growing on drier ground. To utilise the major nutrients as efficiently as possible the farm should be soil sampled and a nutrient management plan used to target slurry to where it is most needed. If you want to know how much N, P and K is in each 1000 gallons of slurry on your farm the DM% can be measured with a slurry hydrometer or alternatively an agitated sample of slurry can be sent to the laboratory for analysis. Typical cattle slurry has a dry matter (DM) of 6% and nutrient profile as in table 1.
| Available N, P & K values of Cattle at different Dry Matter (DM)% in springtime by LESS application techniques | |||
|---|---|---|---|
| Dry Matter % | N kg/m3 (units/1,000 gals) | P kg/m3 (units/1,000 gals) | K kg/m3 (units/1,000 gals) |
| 2 | 0.4 (4) | 0.21 (2) | 1.4 (13) |
| 4 | 0.7 (6) | 0.35 (3) | 2.1 (21) |
| 6 | 1.0 (9) | 0.5 (5) | 3.5 (32) |
| 7 | 1.1 (10) | 0.6 (6) | 4.0 (36) |
| Note - on index 1 & 2 soils reduce slurry P availability by 50% & reduce K availability by 10% | |||
Once you know the nutrient value of your slurry the next step to increasing slurry N efficiency is optimising the timing of application. Spring applications of cattle slurry typically has a higher recovery of N, by up to 50% compared to summer applications. Weather conditions in springtime will reduce N loss through ammonia emissions as days are cooler (<13degrees C), damp and more overcast.
New technologies for the application of slurries have become more common in recent years that have benefits not just from the nutrient recovery side but also reduces losses to waters, decrease Greenhouse gases and ammonia emissions. Low Emission Slurry Spreading (LESS) equipment such as dribble bars, trailing shoe, or injector systems have many benefits over the traditional splash plate such as
- Improved flexibility with application as a result of reduced contamination of herbage leading to a quicker return to grazing
- More even application of spread
- Reduced smells and odours during and after application
Organic fertilisers can be a valuable asset on a farm, but only if managed correctly. By minimising losses through careful application using best practice farmers can retain more nutrients, reduce sward contamination and reduce the fertiliser bill on their farms. This will increase farm profit while helping to protect our air, atmosphere and water quality.
LESS equipment increases slurry N recovery by 50%