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There are plenty of older grass swards on livestock farms that are underperforming. Do these swards need to be ploughed down or can they be brought back to life with a more focused management approach?
These older swards can still have a good level of perennial ryegrass present. With good grazing management and the right level of fertiliser applied, older swards can be improved and have their lifespan extended.
When carried out properly, rejuvenating an existing sward is a much more cost-effective way to reseed and improve existing grassland.
1. Grazing management: setting up older pastures in a rotational grazing system will go a long way to improve the quality of the sward. Set-stocking will have no effect as cattle can freely walk and graze where they like. But with rotational grazing, you will be forcing cattle to graze out all grass present in paddocks.
After grazing, fertilise and rest the sward for 15 to 20 days depending on the time of year and grazing demand, then graze off the sward again in three days.
Repeating this process throughout the year, and from year to year, means that only the more competitive, productive grasses will grow and tiller. This will increase the percentage of ryegrass in the sward and replace older grasses that are less able to regrow in a short period of two weeks.
2. Lime: applying lime every couple of years will improve sward quality as it will raise soil pH. Older permanent grassland can be naturally acidic. Liming ground will help to condition soil, which improves nutrient availability and soil structure. Improved soil structure helps with drainage and allows better plant root development, which improves nutrient uptake. Applying one to two tonnes/acre of lime will suffice.
3. Farmyard manure: plenty of farms have increased the amount of P and K fertiliser they apply, but have seen little improvement in overall soil fertility. Where there is low soil organic matter present, it can be difficult to lift soils from index 1 to index 3. Making better use of farmyard manure can help to improve soil organic matter. When applied regularly, manure will also increase the amount of earthworms present which again improves soil drainage. Farmyard manure is most effective when ploughed in, but regular surface applications are also beneficial.
4. Weed control: persistent weeds such as buttercup or docks can take over a sward if they are not controlled. Spraying weeds is important to prevent them spreading in the sward. Weeds compete with grass for soil nutrients, so the less weeds present, the more grass growth you will have. If there is a high presence of weeds, you may need to spray on several occasions during the season to have a more effective kill. For the best control, it is important that you spray weeds at an early stage before they produce seed.
5. Stitching in grass seed: stitching in grass seed to an existing sward can be a low-cost option to reseeding or rejuvenating a grass sward. It works best where the base of the sward is relatively open as there will be better soil contact. For stitching to be effective, getting soil contact is crucial.
After this, it is important that you keep grazing the existing sward tight, so that you allow light to get to the new seedling. Do not over-graze and rest the sward between grazing. Rotational grazing will work best in this situation.
6. Fertiliser application: adopting a little-and-often approach to spreading fertiliser will encourage the perennial ryegrass to out-compete older grasses and weeds. Spreading 12 to 15 units/acre of nitrogen after every grazing is a much better method to rejuvenating a sward compared with spreading larger quantities of fertiliser after every other grazing. Results will be improved when combined with rotational grazing.
7. Sub-soiling: alleviating soil compaction in an older sward will help to remove surface water and improve soil drainage and soil aeration. As the soil is holding less surface water, soil temperatures will be higher in spring and autumn, which will stimulate early and late season growth of ryegrass.
8. Graze out before closing in autumn: before closing the field up in the autumn, ensure that you have grazed out the sward fully. Older grasses will tend to be less frost resistant than ryegrass and therefore less competitive over winter. This will help to improve ryegrass content that you can build on the following year.
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