Spring is the ideal time to have a good walk through grass swards and see what sort of shape they are in and which ones would benefit from some grassland management.
While a full reseed might not be on the cards, renovating a tired or damaged sward can help revive it to its former glory, according to two grass crop specialists.
Limagrain’s grass seed manager Ian Misselbrook says: “Inspect the sward and see if there is a 70 per cent cover of sown species.” He says a sward full of broadleavedweeds, such as nettles and docks, has ‘help’ written across it.
"But often, weeds which are having a bigger impact on the sward’s productivity are less conspicuous. These are weed grasses, such as meadow grasses, which invade andreplace sown species. “They are less digestible and will not give a good yield response to fertiliser applications.”
Swards achieving 12 tonnes of dry matter/hectare (4.8t/acre) or more are doing well, but if they are yielding 5-10t/ha (2-4t/acre), a successful renovation will improve yields.
Mr Misselbrook says: “While very low yields may warrant a full reseed, most worn-out swards can benefit from renovation, particularly if grass is thin and open and providing there are not too many weeds.”
There are some ‘golden rules’ to follow if this is going to be successful, according to North Wales forage contractor and lecturer Esmor Hughes.
The first is to check the sward for compaction and carry out a soil test to check for P and K deficiencies or adverse acidity. It should have a pH of 6-6.5. Mr Hughes advises looking at the weed population too: “I usually recommend spraying these off so they do not compete with new seedlings. The cost, about £35/ha, is usually worth it.”
Slot seeding, followed by rolling, is often used in pasture renovation using highly vigorous grass seed mixtures known for good establishment, such as Sinclair McGill Turbo, Prosper, Polycrop and, for cutting swards, Colossal Silage.
These short- and medium-term mixtures carry the LG Animal Nutrition (LGAN) accreditation for their proven agronomy and nutritional qualities. They are also treated with HEADSTART Gold, a biostimulant which stimulates root and shoot growth.
Mr Hughes says: “It is all about giving new seeds the best possible chance. I find Polycrop especially good. It is a dual-purpose mixture and grows vigorously.“
"Colossal Silage is ideal for boosting cutting swards, and both have superb emergence rates.”
Mr Hughes encourages farmers, in most cases, to opt for full seed rate.
He says: “Do not compromise, as the difference between using two-thirds and full seed rates is about £50/ha, but you will recoup this in most cases with better establishment and a more productive sward. It is an insurance against potential pest or weather problems.
“I also recommend slug pellets when sowing. I have seen pastures ruined with slugs in this area. They use slots as a runway and target tasty young leaves. Rolling helps, as a consolidated seedbed reduces slugs’ mobility.”
Sward management is crucial in the four weeks post-sowing.
Mr Hughes says: “The new seed has to be able to compete on a level playing field. So graze tightly for the first 10-14 days after drilling so older established grasses, or weeds, do not grow and suppress new seeds.
“Then take the stock off and leave the sward to rejuvenate and avoid putting livestock back onto it too early, or they will pull new plants out before they are properly established, and you will be no further forward.”
Renovating swards can significantly increase production.
Mr Misselbrook says: “It is possible to double their output.”
He adds that it also provides the opportunity to introduce high protein, nitrogen-fixing clovers, which will extend the life of the ley: “Newer varieties can be introduced which bring improved feed value. So by renovating grassland, livestock get access to more productive and better quality grazing, making it a cost-effective option.”