Effective Grassland Management and Reseeding

Why reseed?

Everyone knows that grass is Ireland’s outstanding natural resource.  We also know that nature will always respond to a genuine helping hand especially in the form of efficient management.

That’s the base from which Irish farmers produce more and better grass and enjoy the resulting benefits. For example, improved quality in grassland means:   

Grazing: higher stocking rate and increased profit per forage acre.

Silage: improved liveweight gains and higher milk yields with less concentrates.

Quality: grass sward, deteriorates more quickly when cut for silage. Good management keeps it more vigorous and maintains its quality.    


Deterioration of grassland with age

Swards deteriorate quickly after just a few years.  Within 3 years quality has dropped by 20%, after 4 years it is down by 26%, and by 5 years its quality is virtually halved.


Weeds cost money

You pay a big penalty, in production terms when weeds become established in the sward.  They compete for nutrients and moisture,  essential elements that your grass needs to grow.  As a result, grass grows much slower and the weeds reduce digestibility and palatability.

Grasses other than rye-grass give a poor return for money spent on fertilisers.  From a kilo of nitrogen, rye-grass can deliver 20-25 kg of dry matter, while other grasses achieve only half of that or even less.

New swards will deliver an average yield increase of 25% in the first year ie. 1 tonne/acre of additional dry matter, saving on bought in concentrates, allowing increased stocking rates or releasing land for other uses.  And the yield can increase even more in the second year.

When to reseed?

The following factors indicate a need to reseed:

  • Falling yields - fewer trailer loads of silage or bales of hay.
  • A decline in the number of grazing days.
  • A poor response to Nitrogen is noted.
  • Stock prefer to graze elsewhere.
  • Troublesome broad-leaved and grass weeds cannot be effectively controlled.
  • Sward is looking worn out. 
  • Even in an apparently weed free sward, as a rule of thumb when the sward comprises less than 30% rye-grass it is time to reseed.

Timing Options

Roundup Brands may be applied either before cutting for hay or silage, or to the regrowth of swards and weeds after cutting.

Pre-cut application:

Spray prior to cutting or grazing grass crops between June and October, usually pre-2nd or 3rd cut.  Compared to post-cut treatment, applications at this time allow for an efficient use of the growing season as no time is wasted waiting for cut fields to regrow.

Post-cut application:

After cutting or grazing allow a period of 3-6 weeks for the grass and weeds to regrow before spraying. These diagrams show examples of how the system fits in with accepted farming practices.

How to reseed

Effective sward desiccation is a vital step to successful reseeding.  Spraying Roundup Brands are strongly advised.  It removes difficult weeds such as Scutch, Bent grass, Docks and Thistles.  Roundup Brands have the flexibility to be applied either before grazing or cutting for hay or silage, or to the regrowth of swards and weeds after cutting or grazing.  Livestock acceptability and feed value of treated grass is equal to that normally expected.

For effective grassland destruction and successful establishment use the following three step approach.

1. Spray off old sward 5-days prior to cutting or grazing.  

2. Utilise grass as normal

3. Check for, and correct, any underlying problems (pH. Frit Fly, Soil Compaction, Soil Fertility etc).

4. Once the grass is removed from the pasture establishment of the new ley can begin.



Peace of Mind

Livestock feeding studies show that treatment of grass with Roundup Brands make no difference to the recorded palatability and digestibility of forage compared with that normally expected.  Similarly, the liveweight gain of animals fed on treated forage was also unaffected. 

Roundup Brands are harmless to animals.  The active ingredient does not remain or accumulate in livestock.  No adverse effects have been observed on wildlife, such as rabbits, horses, bees. birds or soil organisms.

Spray pre-cut with the knowledge you have used one of the safest herbicides available.



  • Flexibility to be used not only post-cut, but also pre-cut of silage/hay, or pre-graze of grass
  • Complete kill of sward grass and difficult weed problems, such as Docks, Thistles, Nettles and Scutch, ensuring a weed-free Clean Start for the next crop.
  • No waste – Full utilisation of treated grass – not only is feed value maintained but silage effluent is reduced.  
  • Increased grass yields, not just in first year, save on bought in feed and concentrates
  • Maximise the growing season - pre-cut application saves 3-6 weeks regrowth period and establishes new grass sooner
  • Highest levels of safety to the operator, livestock and the environment.
  • Easier seedbed cultivation