Reseeding is a costly exercise at over €300/acre. Yet, it is one of the best investments farmers can make as the return on investment is very high, with a payback period of about two years. However, that return will only be generated if the job is done correctly and if the reseeds are managed correctly after sowing. The following are key points when reseeding.

1 Timing: this will depend on weather conditions and grass supply on farms.

Autumn reseeding is most popular among farmers as demand from a feed budget point of view on farms is generally lower. However, autumn reseeding has its challenges: lower soil temperatures, variable weather conditions and reduced chances to graze the new sward heading into winter. On the other hand, spring reseeding is a lot more flexible and should be prioritised, where possible.

2 Turnaround: turnaround time is where the biggest win is.

The target turnaround time in which to get a reseed back into production should be 60 days.

Farmers are slow to reseed as they are afraid paddocks will be out of production for too long but old permanent pasture reseeded in spring with a short turnaround time can yield as much as the old sward would have, despite being out of production for over two months.

3 Soil fertility: reseeding will improve productivity of a sward but for it to have maximum effect, soil fertility must be correct. A soil test should be carried out to find the phosphorus (P), potash (K) and lime requirements before reseeding. The test will determine the level of fertiliser needed for perennial ryegrass germination, establishment and production.

Reseeds at the ideal stage for spraying.

If pH is not at the target of 6.3, reseeding is an ideal time to spread lime. Lime can be spread at a rate of 7.5t/ha (3t/ac) in a single application at reseeding. The decaying of the old sward can lead to acidity in the soil. Lime at reseeding is always recommended to counteract this, particularly if using minimum tillage techniques.

4 Variety: when choosing the best variety to sow, select varieties from the Irish recommended list.

The pasture profit index (PPI) puts a monetary value (€/ha) on each variety on the recommended list. The key point to know when choosing a grass mixture is the end use of the paddock – is it for a grazing or silage? Know the type of land being reseeded – is it dry or wet land? Choose your varieties based on the end use. You want less than seven days’ range in heading date between varieties and there should be no more than three or four varieties in a mix.

5 Cultivation: cultivation techniques will differ from farm to farm and even from paddock to paddock. Choose a cultivation technique or sowing method that suits your farm or particular paddock. Once everything is done correctly, there is little difference between the methods. The four main methods are ploughing, discing, one-pass and direct drill:

Ploughing is the best method to use when field surfaces are uneven and need to be levelled. When ploughing, the main thing is to avoid ploughing too deep (more than 15cm) as this can bury the top layer of soil, which is the most fertile soil. Aim to develop a fine, firm and level seedbed. The use of a land leveller will help to generate this. If the seedbed is cloddy and loose, grass seed will be buried too deep and will not germinate.

Discing and the one-pass system is as good a method as ploughing and may be the preferred option where only minimum tillage is needed.

The main thing to remember when discing is to graze tight beforehand and aim to disc harrow the field two or three times in angled directions to break the sod and turn up enough soil to form a seedbed.

A one-pass system can often leave you with rough and patchy swards.

The main thing is to maintain a slow forward speed at cultivation to ensure a better finish.

Of all methods, direct-drill probably leaves the most variable of results as it can be difficult for seeds to establish as there is no cultivation of the soil. It is not suited to very dry, hard ground in dry weather.

Again, grazing tight beforehand is essential. Apply lime if needed and also slug pellets are advisable when using this method.

Ideally, wait for moist ground conditions, spread your fertiliser and direct-drill the seed.

6 Management of reseeded swards: it takes a new reseed 11 months to fully establish and management in this period is very important. In the first eight weeks, you need to spray the new grass for weeds, get nitrogen and extra P and K out and, most importantly, graze the paddock. You should be aiming to graze the paddock when grass is at the two-leaf stage around 700kg to 1,000kg DM/ha. Avoid grazing high covers of more than 1,200kg DM/ha and don’t harvest for silage as this will prevent tillering.

Target grazing the field with calves or young stock for the first time to minimise damage, if possible. From the second grazing onwards, graze the field at 1,000kg DM/ha to 1,400kg DM/ha. Avoid poaching the field. Graze the field tight to encourage tillering, which will lead to a denser sward.

7 Fertiliser: lime and P and K fertiliser rates will depend on soil test results. The most common fertiliser used at reseeding is generally three bags of 10:10:20 per acre, which is meeting requirements for good root and tiller development in index 3 soils for P and K. Extra P and K will be required post-establishment for low soil fertility. Nitrogen is essential for good grass establishment and growth. Grass seeds have a low N requirement during the early stages of growth, so be careful not to go with too much early on as it can promote the growth of weeds. Apply approximately 30 units/acre at sowing and another 30 units/acre four to six weeks after sowing.

8 Weed and pest control: weeds are best controlled at the two- to three-leaf stage. Chickweed and docks are the two most critical weeds to control in a new reseed. An application of a herbicide spray at this stage will usually be good enough to control them. Herbicide choice is important as you need to target the particular weed problem you may have.

Talking to your local adviser or merchant representative at this stage would be advisable. If clover is sown, use a clover-safe spray.

Pests can also cause a problem around reseeding, with frit fly, leatherjackets and slugs being the most common. Frit flies and leatherjackets can be controlled by applying an insecticide. Where a slug attack is a problem, slug pellets should be used.

A fine, firm seedbed can help to control many pests.