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Grassland management is a core part of the Northern Ireland Sheep Programme, from grass budgeting, rotational grazing, soil fertility and improving sward quality.
Reseeding older, less productive swards has been a tried and tested method of improving grass growth throughout the grazing season.
Younger swards are also much more responsive to nitrogen applications, something which has come under the spotlight given the cost of fertiliser this year.
On Dermot McAleese’s farm at Loughguile, Co Antrim, there is a plan in place to reseed part of the farm this year following the successful establishment of new swards on the silage block in recent years.
This year, Dermot is aiming to continue reseeding silage, but also to begin rejuvenating some of the grazing farm.
Challenges
Reseeding on Dermot’s farm is not a straightforward task. The farm is fragmented and most of the grazing ground is upland and hill ground.
Timing a reseed is also important on the farm, as it is located at the northern end of the country, and with its upland location, spring growth is slower to materialise.
The upland and improved grazing areas are also needed for breeding sheep in late autumn, as well as turning ewes out to pasture after lambing.
The farm also receives a high volume of rainfall, so the window for getting work completed is quite short.
From experience, Dermot states that reseeds carried out in June and July stand the best chance of a successful establishment.
Reseeding later than this is much more risky, with Dermot saying that grass growth is quick to tail off in early autumn.
This would leave seedling grass struggling to establish an adequate amount to withstand colder temperatures and heavy frosts during winter.
Reseeding grazing swards
Dermot has identified 8ac of upland grazing which is split across four smaller paddocks that have boundaries marked by stone walls.
The 8ac is part of a larger grazing block close to the home farm. This block normally carries spring-calving suckler cows with calves at foot, as well as ewes and lambs from Dermot’s upland flock of crossbred ewes during the summer.
The sward consists of older grasses that struggle to keep up with grazing demand in late summer.
Soil sampling
Back in January, soil samples were taken on the 8ac as part of a wider farm sampling exercise.
Dermot says that the results were at optimum levels for fertility. Soil pH is 6.4, while phosphorous (P) and potash (K) levels are both at index 2+.
The outlined soil analysis reaffirmed the decision to proceed with reseeding the 8ac this year, despite the rise in input costs.
Younger grasses would give a much higher growth response on such soils at the same level of fertiliser inputs.
Soil structure
Last week, Dermot and programme adviser Senan White walked the fields identified for reseeding. At various points, holes were dug to view soil structure.
There were no visible signs of compaction present, which was a huge positive, as it offered the option of reseeding using a stitching or direct drilling method.
The fields also have no visible signs of any drainage problems, which is another positive and significant cost saving.
Reseeding method
Dermot also says that soils have a high stone content, so he has ruled out ploughing before sowing new grass.
However, given that the base of the sward is extremely dense from sheep grazing, direct drilling grass seed is not an option.
Stitching in grass, even after burning off the existing sward, would also be challenging without breaking up the existing sward base.
This means the reseeds should come back in to the grazing platform much faster, taking the pressure off later in the year
Therefore, to improve the level of soil contact for grass seed, Dermot intends to burn off the sward, graze off the dead matter, then rotavate.
This will open the soil surface and create a better seedbed. Grass seed will then be sown using a tine harrow with pneumatic seeder attached.
The exact same method was used to reseed silage ground last year and works extremely well. All field work, with the exception of drilling grass seed, was carried out by Dermot.
As this method does not disturb the seedbed to the same extent as a ploughed reseed, the ground is better equipped to carry livestock once the new sward has established. This means the reseeds should come back in to the grazing platform much faster, taking the pressure off later in the year.
Lime
While the soil analysis indicated that pH was at optimum levels, Dermot intends to spread 1t/ac of ground limestone before rotavating the burned off sward.
The reason for this is the dead grass can make the seedbed acidic, thereby hindering new grass seed from germinating properly.
Lime will neutralise the seedbed and encourage a swift germination. This will get the new swards established as quickly as possible.
Grass varieties
As the reseed will again be used for grazing, grass varieties will be mainly late-heading diploids that have good tillering potential.
Clover will also be included in the mix, with white small and medium-sized varieties to suit both sheep and cattle grazing.
Post-grazing management
With the farm running a large sheep enterprise, these animals are used to good effect to manage swards after reseeding.
As sheep are selective grazers and can clean out a sward tight to the ground, Dermot has so far not required any post-emergence sprays to control weeds in new swards.
Silage ground
The main silage block on the farm surrounds the home farm and last year, 6ac were reseeded, with a similar area to be reseeded this year again.
Swards will be reseeded after first cut using the same methods as outlined for the grazing block. Last year’s reseed has worked well.
Dermot maintains that reseeded grass is quicker to grow in spring, yields more grass in first cut and regrowth is up to two weeks faster compared to the old grasses on the area that will be reseeded this year.
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