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Eamon & Donnchadh McCarthy May/June Update 2024

Silage & fertiliser

Silage & fertiliser

  • First cut silage started
  • Fertilising for second cut
  • Decisions about housing heifers for finishing to reduce demand
Finishing update

Finishing update

  • Three more groups of bulls drafted for finishing
  • Factory performance of them
  • Remaining bulls can now be separated by weight for feeding
Fertiliser limits for 2024

Fertiliser limits for 2024

  • Calculating fertiliser bought so far this year
  • Working out how much more can be bought
  • Reminder not to exceed limits (NB)


Silage was harvested on 21st May. The silage fields were grazed in spring and fertilised with slurry and protected urea. They yielded just over 10 bales per acre which means that 183 bales of silage are now back in the yard for next winter. 610 bales are needed for next winter so fertilising the ground for a second cut of silage is the next priority.

Slurry will be spread back on silage ground at a rate of 2500 gallons/acre to help replace nutrient offtakes. This will be topped up with 2 bags of 29% protected urea + 14% K + S/acre to supply 76 units of nitrogen, 12 units of phosphorous (P) and 103 units of potassium (K) per acre.

Cow and calf at grassFigure 1: Spring cow and calf at grass

Grass management is going okay on the farm, although Eamon has noticed that the herd is going through grass slightly faster than expected. Grass growth has heled well at 71 kg DM/ha/day between 1st and 7th June but it is expected to drop back due to the latest weather conditions. Demand is at 54 kg DM/ha/day and Eamon is considering housing 7 autumn heifers for finishing to reduce demand as the weanlings’ appetites increase. At 15 days ahead of grass he is comfortable at present but made the decision a few weeks ago to graze some fields that were previously closed for silage which has helped drop the demand on the farm. He is grazing covers at approximately 1400 kg DM/ha and will walk the farm again this week to monitor growth.

Grass wedgeFigure 2: Grass wedge for 7th June 2024


Nine further bulls were drafted for finishing. Three bulls went to the factory on 25th April at 14.3 months of age and they averaged 412kg carcass weight, grading U=3+ and averaging €2296/head.

Three more bulls went on 10th May at 14.6 months of age and averaged 412kg carcass weight, grading U=3+ and averaging €2236/head.

The latest 3 bulls were finished on 27th May at 15.4 months of age. They averaged 657kg (628 to 696kg) live weight on 23rd May and gained 1.41 kg/day since 10th May. They were 390kg carcass weight and graded U=3- making €2184 on average.

The remaining 11 bulls will be moved across from the lean to shed to the new shed for finishing and can be penned and fed according to weight.

Finishing bullsFigure 3: Some of the most recently finished bulls

Soil Fertility

Eamon has been calculating his fertiliser limits for 2024. According to his 2024 nutrient management plan which contain the latest soil sample results, he is permitted to spread 6790 kg N and 513 kg P.

To date he has purchased the following fertiliser:

  • 375t of 46% protected urea
  • 3t of 38% protected urea + S
  • 3t of 29% protected urea + 14% K + S
  • 4t of 18-6-12
  • 2t of 13-6-20

To calculate how many kg of P and K he has bought so far, he must do the following for each compound:

  • Multiply the units per tonne by 20 (e.g. 46% pro urea x 20 = 920 units N per tonne fertiliser)
  • Divide it by 2 to convert to kg (e.g. 920 units / 2 = 460 kg N per tonne)
  • Multiply by the total tonnage (e.g. 0.375t x 460 kg N = 172.5 kg N)

In total he has purchased 3162 kg of nitrogen and 360 kg phosphorus this year. When this is subtracted from the total allowances, it means that he can still buy 3628 kg N and 153 kg P. To work this back into fertiliser terms, it can be calculated as follows;

  • P allowance of 153kg divided by 60 kg N/t = 2.55t of 18-6-12
  • An extra 2.55t of 18-6-12 also contains 459 kg nitrogen (calculated the same as above)
  • This leaves a nitrogen allowance of 3169 kg N when subtracted from 3628 kg N
  • N allowance of 3169 divided by 460 kg N/t = 8 t 46% protected urea

Eamon and Donnchadh will not need to spread that quantity of fertiliser, and still have fertiliser that was bought earlier in the year, but it is important to track their fertiliser usage and limits as it could lead to penalties if they exceed their allowances.

Cows and calves at grassFigure 4: With cows and calves moving quickly through paddocks, now is a good time to check fertiliser use and allowances