The direct impact of reseeding

Tuesday 24.03.2020 , News

Increasing grassland productivity has never been more important. Optimising the production of grass at farm level will have an immediate impact on animal performance.

With soil temperatures above normal for this time of year, and ground conditions improving, now is the time to be planning your spring reseeding.

The average level of grass produced nationally is 9.1 t DM/ha, with the top farms producing over 15 t DM/ha. Comparing these two figures shows just how much scope there is to increase the total grass grown and hence, increase grass in the diet, while reducing feed costs in livestock production systems. To achieve the target of 10 t DM utilised per hectare, assuming 75% utilisation, a farm needs to be growing 14 t DM/ha.

The fundamental goal from reseeding is to increase the perennial ryegrass (PRG) content in swards. PRG dominant pastures will:

  • Provide more grass at the shoulders of the season (early spring and late autumn)
  • Be 25% more responsive to fertiliser N compared to old permanent pasture
  • Increase feeding quality
  • Faster re-growth
  • Increase total production and therefore increase the carrying capacity of the farm

In order to reap the above mentioned rewards from reseeded pastures, there are a few pre-reseeding requirements.

Soil fertility

Soil fertility is critical to maximising the performance and longevity of swards on farms. With Teagasc recently highlighting that 90% of all soils are sub-optimal in terms of pH, phosphorus (P) or potassium (K), without doubt, this is costing farms significantly throughout the country. It directly leads to under-performing grass swards and the necessity to bring in more expensive supplements to overcome grass deficits in the system. Completing regular soil fertility tests on your farm (every 3 to 5 years) and using the results to develop a fertiliser and lime application program is critical to ensure you can get the most from your swards.

Timing of reseeding

There are a number of reasons why we should give more consideration to a spring reseed. In spring, days are getting longer and temperatures are improving – both will help give the new reseed the best start. The improving weather conditions also mean the reseed can be completed with a quicker turnaround time from spraying the old sward to grazing the new sward. It also provides a greater window of opportunity to complete a post-emergence spray and allow for several grazings of the new reseed before autumn closing, which will help ensure a weed-free, well tillered sward, ready for grazing the following spring.

Deciding on what fields to reseed

The general recommendation is to reseed 10 to 15% of the farm per year to maximise the quality and performance of your swards. The best way to identify the poorer performing paddocks on your farm is to complete a weekly farm walk and assess the total production of individual paddocks. Those paddocks producing less grass should be targeted for reseeding. Other ways to identify what paddocks need reseeding are to consider the following:

  • Is there a high presence of weeds such as docks, thistles, etc
  • Has there being severe poaching of a field?
  • Is there a high content of unproductive grasses such as meadow grass, bent grasses, etc
  • Is there less silage being harvested from the field compared to previous years?
  • Is regrowth slow after cutting or grazing?
  • Is there a poor response to nitrogen?

If you have identified a field where one or more of the above points are true, then maybe that is the field you need to consider for reseeding next. If there is a particular issue with soil fertility, then you will need to address that on a regular basis going forward.