Now is the prefect time to reseed grass leys in England and Wales – but at £420/ha (£84/ha/year over five years) it pays to do the job well. Rod Bonshor of Oliver Seeds speaks to Louise Hartley about getting it right.
Few farmers can keep a long-term ley truly productive for more than 10 years, and a poor sward will disappoint in the quantity and quality of feed it provides. Established with care and managed well thereafter, a new ley can deliver low cost, nutritious feed for five to seven years.
Most forage grasses can be sown between March and October when the soil is warm and moist. The most important aspect is to ensure that conditions are appropriate for cultivations – neither too wet nor too dry.
Rye-grasses can be drilled successfully until the end of September, and into October if the weather stays favorable. Legumes such as clover and lucerne prefer to be in the ground before the end of August.
Seed bed preparation is the most critical part of reseeding. Destroy by spraying with herbicide or bury by ploughing, all the previous grass sward or shed arable seed.
After ploughing, shallow cultivation is required, finishing off with light harrows or a harrow comb to produce a final tilth. Firm with a Cambridge roll before broadcasting or drilling with an appropriate seeds mixture, chosen with thought for the site and intended end-use.
After seeding, consolidating the ground ie essential to:
Ensure good seed to soil contact to maximise the speed of germination and encourage faster establishment.
Retain as much moisture as possible.
Make the sward more resistant to poaching during the first grazing.
However, do not compact or flatten the surface too much, as there is a danger of capping after heavy rain, which will impede the emerging shoots of young grass.
Once the seed has germinated – usually within two to three weeks, it is important to manage it correctly. With autumn reseeds, avoid excess growth going into the winter to give slower establishing species such as timothy, chance to compete with the more vigorous rye-grasses.
Check for weed seedlings within a month of emergence. These are more susceptible to herbicides than mature plants (especially docks) and are cheaper and easier to control at this stage.
In most cases, establishing grass will compete well against pest attack, unless it was drilled in less than ideal conditions, or bad weather has limited the vigour of the new grass.
Frit fly cause most damage in August to October drillings, particularly where grass is following grass. These can be controlled by spraying at, or before emergence. On organic farms, ploughing or destroying the old sward six weeks before drilling will help, or planting a brassica catch crop as a break. At the very least, creating a firm seedbed will help avoid excessive damage.
Firm seedbeds will also hamper slugs, which are more of a problem with late autumn sowings especially in cloddy seedbeds.
Before reseeding it is important to try and pinpoint why output has declined. Are there nutrient deficiencies or soil structure problems? Or is the current ley just worn out?
Take a soil test to confirm nutrient status. Dig holes across the field to see if compaction is preventing grass roots from penetrating to a decent depth.
Most agricultural species of grass and clover require a pH of 6.0-7.0 with 6.5 ideal. Correct any deficiencies with lime, but no more than 7.5/ha (3t/acre) in one go, unless ploughing down the additional amount.
Phosphate (P) and potash (K) fertiliser should be applied to meet crop need before final cultivations. Refer to Defra RB209 for more details.
Remember the amount of P and K supplied at establishment should be deducted from the first season’s grazing or silage/hay recommendation.