With most grassland reseeding in Pembrokeshire taking place in August and September, farmers are being urged to optimise the benefits by getting everything from soil fertility to establishment right.

If there are less than 60% of sown species remaining, a full reseed will enhance productivity and economic return, say agronomist Rhys Owen.

Getting the timing right and following establishment and management protocols are key to achieving the best results.

“Getting swards back into the rotation comes down to planning and management,’’ says Mr Owen, of ProCam and Field Options.

“The emphasis for success for a full reseed is on getting the structure and nutrition of soils right.’’

Analyse soils for pH, phosphate and potash well in advance of reseeding. Where needed, apply lime to acidic soils to reach a 6.5 pH target. Aim for a phosphate index of 2 and, for potash, 2-.

Including a break crop improves seedbed cleanliness and soil structure.

  • Don't miss our monthly digest of west Wales farming news in Pembrokeshire Farmer, free inside the Western Telegraph on July 31
     

“Where possible, always precede a complete reseed with a forage brassica or cereal crop,’’ Mr Owen recommends.

These ensure a good entry for grass reseeds by controlling weeds and breaking the life-cycle of leatherjackets and other pests.’’

If a break crop can’t be included, combat perennial weeds with alternative weed control measures before reseeding.

“Applying glyphosate will control grass weeds and ensure a clean start,’’ says Mr Owen.

Grass and clover seedbeds need to be “uniform, fine, firm and well-consolidated’’, he adds, to allow good seed-to-soil contact and to retain moisture.

“Too often, seedbeds are ‘fluffy’ because they have been over cultivated or have not been consolidated enough with rollers.’’

In recent years, dry conditions have compromised Pembrokeshire’s spring reseeds, with fat hen and redshank often out-competing young seedlings.

Mr Owen suggests weed pressure is usually lower in August, or into early September, although chickweed can present problems if the land is highly fertile or has a high phosphate index.

Getting the timing right is particularly important for red and white clovers as these must be well established before conditions get colder.

By reseeding early enough the sward can be lightly grazed to promote tillering and to help control or reduce the competitiveness of annual weeds.

Sowing depth is fundamentally important, especially for herbal ley mixes with different seed sizes.

For most species a seeding depth of 10-15mm is adequate.

Mr Owen says broadcasting seed, instead of drilling, gives a more even establishment and overall ground cover.

The importance of adequate rolling pre- and post-seeding “cannot be over-stated’’.

“If in doubt, roll again,’’ he adds.

Grasses and clovers can be grazed once they pass the ‘pull test’ – tugged without uprooting.

Light grazing promotes tillering and encourages grass growth, and cleans up some annual weeds.

It will also enable more light to reach the young clover seedlings lying below the grass canopy.

Weed species must not become too strong before treatment - ideally seedling docks should have no more than two ‘true’ leaves.

For a new grass or clover ley, the first application is the most important herbicide treatment.

Aim to apply this between four and six weeks after emergence.

“Control of perennial weed seedlings and annual weeds can be achieved with a well-timed application of a red and white clover-safe tribenuron methyl herbicide, or an amidosulfuron, which is safe to use on white clover,’’ says Mr Owen.

At application, clovers must have at least one trifoliate leaf.

Adhere to the grazing intervals specified on product labels.

Herbal leys

Many farmers have opted to grow diverse mixes in return for payments under the Growing for the Environment Scheme (GFTE) in Wales.

Herbal leys, red clover, or red clover and ryegrass mixtures dominate in these options, and lucerne features to a lesser degree.

Chemical weed controls can’t be applied to herbal leys, with the exception of glyphosate with a weed-wiper, therefore annual weeds must be controlled by topping or with carefully managed grazing.

Species such as chicory and plantain should have at least six leaves before grazing to allow time for the root system to develop and to aid sward persistence.

Mr Owen recommends planting these in August as establishment success, for red clover in particular, drops very quickly afterwards.

The same timing applies to most herbal leys – they need to be in the ground in mid-August to ensure successful establishment of all grass species, legumes and herbs.