This week’s installment looks at the area of over-seeding or stitching-in grass which has become an increasingly popular method of rejuvenating tired pastures using the least invasive methods.
For those of you not wanting the cost incurred by spraying off, ploughing, discing etc., overseeding is a viable alternative that allows new growth on an established sward.
There are some factors to be taken into consideration however, and this is not a panacea for poor grass cover.
First of all, the pattern should remain the same in preparing your ground, whether it’s a full reseed or stitching in.
Soil samples are important and will allow you to gauge the nutrient requirements of your paddocks and whether, or at what rate, lime should be applied.
If you’ve used the same fertiliser for several consecutive years, chances are your land is either lacking in, or overloaded in, some compound.
Slurry applications need to be planned also, as some paddock will require them more than others. For overseeding, watery slurry applied after seeding can prove very effective, so plan out your usage at the start of the season. With the coated seed, this isn’t required.
One of the criticisms of over-seeding is that the new seedlings are in direct competition with the established sward, competing for light, soil and nutrients.
Establishing good soil contact is vital; nourishing the sward thereafter is equally important.
It’s true that there is no competing with a full reseed, where the entire sward is burnt off and you are starting from scratch with each newly emerging seed.
Growth thereafter is 100% new grass. But don’t let that cross overseeding off your list as it is a valuable, cost-effective exercise that works at effectively thickening the sward while aerating the soil at the same time.
For many farmers who can’t afford to have swards closed off too long and need a quick turnaround, this method ticks the box.
One of the benefits of over-seeding is the relatively low cost compared to your standard reseed. At an average cost of less than €100/acre (as estimated by Teagasc), it equates to one third that of a full reseed.
The process involves a minimally invasive scratching of the surface using a tine harrow. We use a Rakemann 3000, but there are a variety of machines that are capable of performing the same job such as the Einboch or Jarmet.
When selecting a paddock for overseeding ensure that there is minimal trash on the surface which is best achieved by tight grazing or directly after cutting silage. This gives an open, unobstructed bed on which to apply the tines.
A damp surface is ideal and reduces the passes necessary to expose the soil. If it is too dry, it may prove difficult to sufficiently expose enough soil.
Therefore, weather plays a critical role also. Warmth and sufficient moisture are required for germination and growth; sowing in excessively dry conditions can limit the uptake of the seeds.
On an ideal surface, three passes of the tines are sufficient, with the seed being spread on the third pass. If soil contact is sufficient, no rolling is required post-sowing.
Lime may be applied to counter any dead grasses or weeds that emerge from the tining process.
This week’s seed looks at HF Seeds’ GrassMax dual-purpose with Pro-Nitro. Designed specifically for overseeding, each seed comes coated with nitrogen in both fast and slow release forms. This negates the issue of competing with the established grass by giving each new seed a boost.
It is advised not to spread any fertiliser for 2 weeks post-sowing in order to allow germination and establishment of the new seedlings in the sward.
Research has shown a 34% increase in viable plants, and 30% increase in root growth.
The application rate is 12kg/acre; grazing is fine up until the emergence of the seed, with the paddock then closed off to allow sufficient establishment.
Post-emergent grazing is key to successful sward growth; the new grass requires light to formulate and thicken, so regular grazings are necessary to allow for sufficient coverage and the most effective uptake.
Weed management is also important, as the new seedlings do not need to be competing with weeds as well as older pasture. Ensure whatever spray you use is clover-friendly, so as not to affect the white clover blend included in the mix.
The Mix Make-up:
- Xenon (Tetraploid Late Perennial Ryegrass) - a very dense tetraploid seed with excellent grazing and cutting qualities; With excellent forage quality, this seed adds density to the sward, being added to the recommended list in 2016;
- Aspect (T) Late Perennial Ryegrass - an excellent grazing seed and maintains growth throughout the season. Recommended throughout Ireland and the UK;
- Solas (T) - Late Perennial Ryegrass has excellent graze-out capacity and good digestibility;
- Dual-Purpose White Clover Blend.