Overseeding Insights

Every grassland farmer is well aware of the vigour and high level of production that can be achieved from a new reseed and also that inevitably through time, the sown grasses begin to disappear and the sward thins out and production suffers.

The decline of sown species is influenced by many different factors but on average by the time grass reaches 7or 8 years old, only around 60% of the sown species remain and 40% of the sward is either bare ground or occupied by weed grasses.

This deterioration not only affects yield but also has a significant effect on palatability, forage quality,

spring growth and the overall response to fertiliser inputs. When these are added together, the effect on both animal performance and the overall financial return is substantial and a sward with 40 – 50% bare ground or weed grass content can mean a loss of up to £300 per acre per year in feed value.

Recognising the need to maintain a high proportion of sown species in older grass and that a full reseed is not always practical, HF Seeds has developed the GrassMax system of overseeding which presents a real opportunity to restore production in tired or damaged swards to newly sown levels without the expense or disruption of a full reseed.

The GrassMax system of overseeding can also be used to introduce or increase clover levels in existing swards.

The key to successful overseeding lies in ensuring that the newly sown plants are capable of competing with the existing grass and that the germinating seedlings have sufficient vigour to establish successfully in what can be a very competitive environment. Increasing the competitiveness of the establishing plants can be achieved in three ways each of which has a cumulative effect in ensuring success.

1 - Minimise Competition from the Existing Sward

When the existing sward is growing strongly there is obviously more competition for the establishing seedlings. Consequently the timing of the actual overseeding operation and the subsequent fertiliser treatment are important factors to consider. The objective should be

to find a window during the season when the existing sward is short and is not growing strongly. Ideal conditions are provided after a hard graze or immediately after the last silage cut of the season. No fertiliser should be applied for at least 15 days after the overseeding


2 - Use a Mixture Designed for Overseeding

Large seeded grasses are more competitive in their establishment and all the HF GrassMax mixtures are comprised of Tetraploid. Hybrid and Perennial Ryegrasses specially selected for their establishment vigour. The use of these large seeded, aggressively

establishing grasses significantly increases their ability to compete with the existing sward.

3 - Use Mixtures Treated with iSeed® 50

Although conventional fertiliser application will increase the establishment vigour of the

new seedlings, its growth promotion effect on the existing sward is greater and competition

is increased to a level which often overwhelms the establishing plants. For 2014, all HF GrassMax mixtures are available with the unique and revolutionary iSeed® 50 treatment where every individual seed is coated with both nitrogen and phosphate. This unique targeted fertiliser concept feeds the sown seeds and not the surrounding sward and dramatically improves establishment vigour at the most crucial stage in the overseeding process. Extensive trials have shown that the uptake of iSeed® 50 fertiliser is four times more effective than conventional applications and have demonstrated establishment gains of up to 50% and substantial gains to both root and shoot development.