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Consider Overseeding to Rejuvenate Swards

The first cuts of silage have been delayed this season due to adverse weather and poor growing conditions.

Once the first cut is complete, it is generally a good time to evaluate the productivity of existing swards and identify areas for improvement.  If the percentage of perennial ryegrass is still above 50%, then overseeding can be a simple and cost effective means of rejuvenating an older sward.    

As swards increase in age the percentage remaining of the species originally sown will reduce and yields will fall. This is certainly true once swards have been out more than 5-6 years, when creeping bent and some meadow grass species begin to invade.  A major benefit of overseeding is that you can achieve increases in yield and quality without having to take the field out of production for an extended period of time, as would be the case with a full reseed.

All the normal checks should be carried out, including checking for soil compaction and assessing the status of soil fertility - i.e. soil pH, Phosphate (P) and potash (K) levels. Where possible these should be corrected with the aim of achieving a pH of 6.0 - 6.2, and soil indexes of 2 for both P and K. It is important that the old sward has either been grazed down tight or has been cut for silage to provide a non-competitive environment for the new grasses to establish.  If it is possible the sward should then be grazed lightly around five weeks later, rather than cut for silage.

There is a range of drills available locally to carry out the reseeding work including the Moore UniDrill, Einbock and Guttler.  It is important that seed is not drilled too deep as this will reduce the the ability of the grass to get well established;  10-12mm is the optimum depth.

Sowing 9-10 kilos per acre would improve productivity and increase the life of the existing sward by another two to three years.  If the aim is for longer term grazing then use a mix of diploid and tetraploid perennial ryegrass.  If only a short term fix is needed then a hybrid ryegrass like AberEve would be more suitable.  Even a modest increase in yield of 10% will more than cover the additional cost of overseeding.


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