The Value of Reseeding.

Good grass is the foundation of every livestock enterprise and the quality of swards whether for cutting or grazing, can have a huge impact on margins and profitability. Unfortunately, it is difficult to accurately measure production from grass and falls in production often go unnoticed resulting in increased purchases of bought-in feed which could have been avoided.

Every grassland farmer is aware that grass yields decline as the sward ages. The rate of decline is influenced by many different factors and will vary from farm to farm but through time the sown species gradually die out and are replaced by unproductive and poor quality natural and weed grasses. On average after 7 or 8 years, only around 60% of the sown species are still present with the remaining 40% as bare ground or unproductive weed species. This decline in sown species has a huge impact on yield, forage quality, the response to fertiliser and the cost of production of both grazed and cut grass, as can be seen in the table below;

In simple terms, every single acre performing at 75% capacity needs the equivalent of a tonne of barley to fill the gap between 75% and 100% and with many grass fields performing at significantly less than 75% of their potential, unnecessary purchased feed bills can rapidly escalate.

Tips for Reseeding

  • Take a soil sample at 10cm (4 inches) to analyse pH, P and K indices
  • Spray off the old sward and ensure there is enough new growth for the chemical to be taken up
  • Begin cultivations 7 – 10 days after spray off & ensure low level of thrash before cultivating particularly wwhere using minimum cultivation techniques.
  • Apply seedbed fertiliser as required. Apply lime to achieve 6.5 pH at a maximum of 5t/ha (2t/acre), split dress if more is required.  Do not use high nitrogen fertilisers on a grass reseed.
  • Work down to prepare a fine, firm seedbed regardless of cultivation technique.
  • Drill or broadcast the seed onto the rolled seedbed. Ring roll or light harrow to ensure maximum contact between seed and soil. Grass and clovers will not germinate until the average daily soil temperature is above 5ºc. Temperatures need to rise to achieve satisfactory growth.
  • Roll again, ideally with a ring roller
  • Weed control in the new ley is usually necessary to ensure good establishment around six weeks after sowing in normal conditions; herbicide choice will depend on the presence of clover or not.
  • Graze periodically from 8-12cm down to 3-6cm this will help achieve a dense, tillered sward. The removal of grass allows light to reach and stimulate grass tiller buds and clover growing points. Sheep or young stock are less likely to poach the developing sward.
  • If significant weed problems are expected, you may consider establishing the ley without clover and introducing it once a herbicide has been applied to the sward


Good Ley Poor Ley
Yield (t DM/ha) 12t 8t
Forage Quality (MJ ME/kg DM)
12.0 ME 10.5 ME
Response to Fertiliser N (kg:kg)
25:1  15:1
Cost of Production (p/kg DM) -Grazed 3-5p 8-12p
Cost of Production (p/kg DM) -Silage 8-10p 16-20p