Farming Update June 2010

by PJ Phelan

Grassland Management.

Manage grass so as to ensure that grazing animals get leafy grass at all times. Stemmy grass is poor quality and results in poor performance. Do not be tempted to graze headlands of silage fields as neither cows or cattle will not perform well on it. Leafy grass should be grazed to 4 – 4.5cm high – less than 2 inches high. Grass that is allowed to become stemmy will be slow to recover.

In a survey which I carried out a few years ago sulphur deficiency was found to be the most limiting nutrient for grass production on 16 of 40 grass samples analysed. On sulphur deficient land you can expect  a response of 10%-50% more grass by spreading 12 – 20 units per acre of sulphur between now and August. However sulphur interferes with copper uptake so don’t use or over use it if you don’t need it. The easiest way to determine if your land needs sulphur is to split a field/fields and spread nitrogen with sulphur on one side and straight nitrogen on the other side. Alternatively you can spray sulphur on the grass.

Timing the silage cutting date

Grass should be cut when it is at the late vegetative to early flowering so as to produce high quality. Delaying the cut will give a higher yield but will result in slower recovery and reduced total yield from the growing season.

Watery slurry should be spread as soon as possible after cutting.

An application rate of 22m3/ha (2,000 gallons/ac) will give approximately 15 units of Nitrogen /ac. Spread a ½ – 1 bag/ac Nitrogen 5 – 7 days later for aftergrass.

If you wish to take a second cut of silage you will need approximately 2 bags of Nitrogen/ac.


The month of May produces peak milk yield after which you expect to see yield drop by 2 .5% per week (10%/month). If yield drop is greater you need to review your grassland management.

Paddocks should be topped when the “tall” grass areas exceed 25% of the total area. Manage grass so as to avoid having to top more than every second paddock. Top the day after grazing with topper set to 3.5cm (1.5ins).

Grass measurement is a vital tool if you are to make the best use out of the grass you grow.  The grass  yield is calculated by cutting the grass to 3.5 – 4cm from an area of 0.5 X 0.5 m (19.5 X 19.5 ins) and weighing it. The weight is then multiplied by the estimated dry matter (probably only 13-14% this evening, 9th June, after heavy rain  but expect it to be 16 -17% by middle of next week) and then multiplied by 4 :

Weight of grass (g) (from 0.5 X 0.5 square) X dry matter % X 4 = kg DM/ha


Weight of 200g X 14% Dry matter X 4 = 11,200 kg DM/ha

The following are the targets (Kgs DM/ha) for various stocking rates on the grazing area:

Stocking Rate  Pre-grazing cover  Average Farm Cover

(cows/ha)   (S.R. x 17 x 21+100)*                   (S.R. x 170) **

2.0                   815                                        340

2.5                   990                                        425

3.0                 1170                                        510

3.5                 1350                                        595

4.0                 1530                                        680

4.5                 1700                                         765

This has been a very easy season so far to prevent disease in crops. However crops are now about to enter the period of grain fill. It is therefore important to ensure continued green leaf for as long as possible. To do so you should apply the recommended rate of an effective fungicide and in some crops additional nutrients.

Crops that have disease infection, generally rhyncosporium on unsprayed spring barly, will need proline or other good triazole to prevent further spread. All spring barleys crops should get a traizole + Strobiluron + Chlorothalonil after full flag leaf. Winter Wheats look good but need to get their final spray after heading.

Additional nutrients will consist largely of foliar application of trace elements and in some cases of nitrogen and magnesium.

Protect Single Farm Payments

  • Keep herd/flock register up to date – consider registering  for online service
  • Don’t purchase fertiliser unless you have a fertiliser plan, which is available for inspection.
  • Ensure silage effluent is directed to a leak proof tank
  • Don’t allow noxious weeds (Ragworth) to flower
  • Keep veterinary medicines and farm chemicals in a secure store – keep records.
  • Don’t cut or remove hedgerows
  • Collect all plastic film and recycle other spent materials if possible.

PJ Phelan is an Agricultural Advisor. Ph: 086 8046455 or email:

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