Renovation or reseeding is first question
Establishing grass successfully can be tricky. In this special, we look at reseeding options, variety choice, seed rates and maintaining reclaimed hill pastures. We kick off this special, edited by
Emma Penny, with a look at whether to renovate or reseed swards. Jonathan Riley reports
RESEEDS can outyield permanent pasture by 40% but the composition of the existing sward should be checked before opting to reseed.
ADAS grassland team manager John Cook says many producers are reluctant to reseed because of establishment costs of £170/ha (£90/acre).
"This may encourage some producers to take swards on beyond the fifth year. This is possible if swards have been well managed, and some dense swards with a good turf are actually more resistant to poaching.
"But reseeds are capable of generating 16kg DM/kg of nitrogen applied, compared with 12kg DM/kg nitrogen for permanent pasture. And they can be 40% more productive in the first year," says Mr Cook.
"However, reseeding is no substitute for good management and careful decisions must be made when considering reseeding."
South-west-based ADAS grass-land consultant John Wakefield says close inspection of a lush, green pasture can reveal the sward is dominated by poor weed grasses such as creeping bent and meadow grasses.
He suggests producers assess the proportion of ryegrasses present as the basis of reseeding decisions.
"Older swards are dominated by late perennials and lose their early vigour which is vital for producers aiming for an early turnout," says Mr Wakefield.
He advises using a trowel to dig up a handful of grass plants at points across the field and looking for the distinctive purple base of the ryegrass plant.
"Bear in mind that some specialist mixes may contain timothy and cocksfoot – which do not have a purple base – and assess whether ryegrasses make up 60% of the sward."
He suggests that swards with more than 60% ryegrass could be improved with better management rather than reseeding.
"An increase in fertiliser rates on these swards should allow ryegrass to out-compete the weed grasses because ryegrasses use fertiliser more efficiently."
However, once ryegrass content in the sward has slipped below 60%, even the best management will not improve it and so reseeding could be advisable, he says.
In certain situations complete reseeds may not be necessary. Thin soils over shale which cannot be turned may, for example, benefit from stitching in grass seed.
"Again sward composition must be assessed because there is little point in stitching early varieties into a late maturing sward. The earlies will just head and go stalky before the rest of the sward has got going," he explains.
"It is better to thicken up a thin sward by improved management," he says.
Where bare areas have resulted from difficulties at drilling or through drought, swards could be patched up.
"As a rule of thumb if 30% of the sward is gone, then reseed it, otherwise consider patching it up, especially when only 10% of ground is bare."
Mr Wakefield advises harrowing the patches, broadcasting seed, and then rolling to bring up moisture for seed germination.
"Weather also plays a major role in reseeding decisions. If you are wondering whether reseeding could be put off for another year consider the suitability of the weather.
"When there is plenty of moisture and warmth it could be better to reseed now because in 12 months time there might be a drought and establishment would be more difficult," he says.
"It is vital to establish why the sward deteriorated, for example under or over grazing, poor drainage or acidity. This must all be corrected before reseeds are considered," he cautions.
Dig up a handful of grass and look for the distinctive purple base of ryegrass (left), advises John Wakefield. This will dictate whether to reseed or not.
• Will better management help?
• If 30% sward gone, reseed.
• Patch it up if less.