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Organic Manure

Organic manure is a valuable source of plant nutrients. The key aim is to maximise the value of slurry, i.e. get the most from its P and K content as well as N. This will be achieved by making sure that it goes to the right place at the right time at the right rate

  • P & K – Right Place – Spread on fields/paddocks where fertility is low and where the nutrient demand is highest (e.g. silage field)
  • N – Right Time – Spread when potential N losses are low and the potential for uptake by a growing crop is high (February to April)
  • Method – Use a Low Emission Slurry Spreader

Infographic Organic manures Plan your slurry applicationLESS spreader 350 x 156

  1. Calculate the amount of slurry available
  2. Assess nutrient value in the slurry (adjust rate accordingly)
  3. Prioritise silage ground 
  4. Target thicker (higher dry matter) slurry to silage fields 
  5. Direct watery slurry to grazing plots

Slurry application plan  

Plot name or numberPlot sizeCropP IndexK IndexFeb/March gals/ac, m3/haMarch/April gals/ac, m3/ha
5 9 Silage & grazing 3 4   5.4m3/ha, 3,000gals/ac
2 4.5 Grazing 1 2 2.7m3/ha, 1,500gals/ac  

Value of slurry (cattle)

Slurry dry matter %N Units/1,000galsP Units/1,000galsK Units/1,000galsValue €/1,000 gals 
2 - very dilute 4 2 13 16
4 - watery 6 3 21 25
6 - typical  9 5 32 39
7 - thicker 10 6 36 45

Note: On index 1 & 2 soils reduce slurry P availability by 50% and reduce K availability by 10%

Slurry Calibration Tool

Access the Slurry Spreading Calibration Tool here