GRASSLAND RENOVATION ADVICE – Renovating grassland swards to maximise productivity

The benefits of reseeding

Reseeding creates an opportunity to improve the quality and yield of grassland swards and to enhance livestock performance through higher feed intakes. A young, well-managed grassland ley can produce 13.5t DM/ha at an energy content of 12.0-12.5ME. In comparison, an average sward will produce just 7.0t DM/ha at 10.8ME, equating to a loss of 93,150MJ/ha.

The higher yield potential of fresh swards enables stocking density to be increased and offsets the need for bought-in feed. Healthier, more productive swards will also support an extended grazing season, with an extra 30 days at grass saving an estimated £3,725 per 100 cows in housing costs alone.

Reseeding also provides an opportunity to introduce new species such as clover or herbal options such as chicory and plantain which can reduce nutrient inputs and increase protein production. Using a proven mixture of high-quality seed stocks, such as those tested under the Field Options umbrella, will enhance germination rates and produce a more vigorous sward.

Timing

Beyond spring, the best time to overseed is when grass growth slows after grazing or silaging. Clovers and herbal leys must be well established before the winter, so August seeding is preferable, but be aware that dry conditions can hamper establishment and allow weeds to dominate.

Grazing will promote tiller numbers and reduce weed pressure, and can start when grasses and clovers pass the pull test, but chicory and plantain should be allowed to reach at least six leaves before livestock are introduced.

Soil health

Before overseeding commences, damaged soils must be repaired. Compaction should be alleviated before a level, fine and well-consolidated seedbed is created.

Mineral soils should be at pH 6.2 and peaty soils at pH 5.5 to 5.7. Soil nutrient availability should also be assessed: target a phosphate (P) index of 2, and 2- for potash (K), but don’t apply nitrogen until the new sward has established as this can encourage weeds.

Weed and pest control

Reseeding after a brassica or cereal crop provides a chance to control weeds, improve soil structure and disrupt pests such as leatherjackets. Grazing can also control some troublesome perennial weeds, or use glyphosate to create a completely clean seedbed.

Using a programme of herbicides is the most effective way of controlling docks, thistles, nettles and buttercup, but be aware that some multi-species swards can’t be treated with an herbicide, and not all grassland herbicides are safe on clover. Herbicide options are also restricted on land that has been entered into an environmental scheme. And be aware of any cropping restrictions carried over from herbicide applications earlier in the year as these may impact the choice of reseeding mixture.

In all scenarios, it is easier to control weeds at an early growth stage, but make sure the timing and dose rate of the proposed treatment(s) doesn’t have a detrimental impact on sward seedlings – if in doubt, speak to a ProCam agronomist for up-to-date advice for your specific scenario.

Drilling and establishment techniques

Using a seed drill or broadcasting are both viable options, but as a rule of thumb, broadcasting will give better tillering and ground cover when seeding long-term mixtures. When using a drill, place the seed at a depth of 10mm and, for better ground cover, drill in two passes at 45 degrees to each other. Rolling should also be done at an angle to close drill slots and improve seed-soil contact.

More information

For more reseeding advice, and to find out more about the Field Options range of grass and forage seeds, download the latest Field Options catalogue HERE