In recent weeks, many farmers have baled or ensiled exceptionally large quantities of second cut silage.

With 10 bales per acre commonplace, swards will be very slow to recover. Nutrient status has also been potentially run down, while a very heavy cut will inevitably reduce the life of productive grasses, increasing the potential for weed grasses to take over.

However, with rain in the forecast and swards slow to re-grow, it perhaps has created an opportunity to get some new seed into the ground without going to the cost and added work that comes from ploughing.

There is also plenty of moisture in the ground, so it is not that difficult to create some tilth by two runs with a power harrow or with a set of heavy discs, followed by a couple of runs with a chain harrow.

As with any reseeding project, it is vital to ensure soil pH is above six. A short-term fix is to go in with 100kg per acre of granulated lime. It will also help to counteract any acidity from decaying grass that can inhibit germination of the new seed.

Burning off the sward followed by ploughing remains the most reliable way of reseeding a sward.

When it comes to seed selection, it is best to use mixtures that have a high proportion of tetraploid perennial ryegrass, as seeds from these grasses tend to be larger than diploid varieties so have a better chance of getting established in an existing sward.

Ideally the seed is direct drilled into the sward, but if sufficient tilth has been created, the seed can be broadcast using a standard sower.

In all cases, it is necessary to roll the field to ensure sufficient soil to seed contact, or alternatively graze the field with sheep for seven to 10 days post-sowing.

The amount of fertiliser applied will depend on soil analysis and whether slurry was spread after a second cut. But where a large bulk of grass was removed, this will have depleted potassium (K) reserves, in particular.

The best advice is to use a compound product low in nitrogen as there is a danger that by applying N, it will encourage existing grasses to out-compete the newly sown seeds.

The sward will be ready for grazing once new grasses cannot be pulled from the soil by hand. This tends to be when the new grass is 6cm to 8cm in height.

It is important to get a couple of grazings done before winter to encourage tillering of the new grasses.

Pros and cons of minimum cultivation

The main advantage of using a minimum cultivation method to rejuvenate a sward is obviously the lower cost.

It will also involve much lower risk when compared to burning off/ploughing. This means there are no stones to be lifted, and delivers a much faster turnaround.

If completed within the next week, the sward should be available for a light grazing before the end of September.

Following baling of second cut, this sward received three runs with a set of discs, and a couple of passes with a chain harrow before granulated lime was spread and seed was broadcast. The sward was then rolled.

Given that the sward was not ploughed, it should be able to withstand that grazing even if conditions are not ideal.

There is also a greater window to deal with any resultant weeds – in conventional September reseeds it is often impossible to deal with weeds until the spring, allowing chickweed to choke out patches of the new sward.


The most reliable scenario when reseeding is to burn off the sward ahead of ploughing, power harrowing etc. Ultimately anything less than this will not be as effective, and in practice, utilising a minimal cultivation technique is simply prolonging the life of a sward.

Ploughing also creates an opportunity to open up the soil, alleviating any surface compaction issues.

Tetraploids on recommended lists

If stitching in grass seed to an existing sward, advice is to use mixtures that contain a high proportion of tetraploid perennial ryegrass. Ideally these varieties should be included on recommended lists.

However, on the back of budget pressures at AFBI, a recommended list of grass and clover has not been published in NI since 2016. That leaves farmers with no other option but to refer to the Teagasc list in the Republic of Ireland and to lists published in Britain.

Shown in Table 1 are tetraploids on the Teagasc list ranked by Pasture Profit Index – a model which assigns economic values to a number of important traits, including grass yield, quality and persistency.

There are four tetraploid varieties bred at AFBI Loughgall which appear on the Teagasc list. All four are also on the list for England and Wales, alongside Seagoe and the new varieties, Banbridge and Tollymore.

Cost savings with minimum cultivation reseeding

The costs involved with reseeding grassland have increased over the past two years.

Contractor charges for drilling into an existing sward will typically cost around £25/acre, rising close to £35/acre where two runs of the drill are required due to heavy residual covers of dead grass.

In contrast, ploughing will cost £30 to £35/acre using a contractor with a further £35 to £40/acre charge for a one pass operation to till ploughed soils and drill seed.

Discing or power harrowing will cost around £20 to £25/acre with a grass drill at £15 to £20/acre.

There are potential savings on contractor charges where bigger acreages are covered.


At the outlined costs, the plough and drill method will cost in the region of £70/acre to get grass seed established.

In contrast, minimum tillage methods will work out £35 to £40/acre cheaper.

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