In this article, we will discuss the benefits of reseeding, available options, choosing the correct grass mixture, getting soil fertility right, techniques for reseeding, and the optimum timeframe to conduct this task.
Reseeding is an extremely important aspect of grassland productivity on farms. However, reseeding levels in Ireland are subsequently low.
Teagasc research has found that less than 2% of Irish grassland area is reseeded annually.
You should consider several aspects to ensure that reseeding grassland is successful. Yet, ensuring that your soil health is correct is a key criterion.
For approximately €300/acre (€750/ha), reseeding is an expensive farm management task, but one that is considered a worthwhile investment.
Getting soil fertility right for a reseed
Soil fertility is vital to allow for a reseed to establish correctly. Procedures such as soil testing can provide you with this information. Hereafter, soil testing should occur before reseeding, ideally in the autumn.
Before reseeding, you can take serious steps to ensure that you provide the ideal soil conditions.
In terms of nutrient application, do not apply for more than 3 tonnes/acre in a single application of lime. Also, P and K levels should be at index 3.
Nitrogen is an essential macronutrient for the establishment of good grass. To ensure an adequate supply, apply 40kg N/ha when reseeding.
Following the reseed, paddocks should be soil tested again in the following year to ensure the fertility of the soil is optimal for grass growth.
The benefits of a reseed
The benefits of adopting a reseeding programme on Irish farms are well proven and documented through ongoing research.
While there is a high level of management required to ensure the process is carried out properly, increased production levels with improved grass quality ensure the effort of reseeding is quickly recouped within two years.
There are numerous benefits to reseeding, such as:
- The ability to carry more stock;
- Increase live-weight gain;
- Efficient nitrogen usage – higher response from your fertiliser;
- Earlier grass growth as well as grass growth following on later in the year with a faster re-growth;
- Higher animal output – 8% higher milk output per hectare compared to permanent pasture;
- Improvement in silage quality – according to Teagasc, a silage DMD increase from 68 to 72 % will reduce meal feeding by 1kg/head/day.
The time to reseed
In Ireland, the majority of reseeding takes place in autumn. This is generally due to feeding allocations and the higher demand for grass in the Springtime.
Nonetheless, due to unpredictable soil conditions in autumn, spring reseeding certainly offers greater flexibility in terms of ground conditions, as well as the ability to apply post-emergence sprays.
In autumn, pest damage can also be an issue. In the same way, more stable and reliable soil conditions in spring generally offer more success for the establishment of white clover.
Still, regardless of when you are considering conducting your reseed, it will usually take around 11 months to establish fully.
A sward can be back in production in 60 days. You can reduce the time the sward is out of action by cultivating 7-10 days after spraying off the old grass.
On the other hand, this emphasises the importance of not waiting too long after spraying off. This Is weather dependent. On the contrary, in spring, conditions tend to be less severe than in autumn.
Managing a new reseed
Initial management of this newly reseeded sward is key to its future persistency and output.
In the first eight weeks:
- Spray weeks before grazing;
- Graze when the grass is at the 2-leaf stage (approximately 700-1000kg DM/ha), grazing by lighter animals such as calves or sheep may be a better alternative.
Post-8-weeks:
- Graze at 1,000 – 1,400kg DM/ha (6-7cm);
- Respray weeks if required.
Autumn:
- Graze off well before the first Winter (below 4cm);
- Apply a light slurry application.
Year 2:
- New swards should receive an adequate supply of nitrogen;
- Monitor P and K index.
Techniques for reseeding
Ploughing is a common technique adopted by Irish farmers when conducting a reseed. Avoid ploughing too deep – i.e. deeper than 15cm into the soil. By doing this, you can bury the top layer of soil, which is the most fertile layer.
To successfully cultivate through ploughing, shallow plough to develop a firm, fine and level seedbed.
A second cultivation technique for reseeding is discing. When adopting this technique, you should not drive fast with forwarding speed, which would create a rough, uneven seedbed. Graze tight before discing, apply lime and disc two to three passes in angled directions.
Likewise, the one-pass cultivation has a similar recommended guideline to discing. The slower the forward speed of the machine, the better the finish.
Direct drilling has a distinct disadvantage compared to ploughing when considering initial establishment.
Moreover, direct drilling creates a difficult environment for seeds to establish, as there is no soil cultivation. In the same way, results can be variable.
Choosing the appropriate grass seed
The number one thing to consider is the primary use of the field – are you reseeding your sward for grazing or silage?
There are two types of cultivars, tetraploid and diploid. Combining both will create a dense, high-quality sward.
For improved ground cover, increase the proportion of diploids in your grass mixture.
There should be no more than three to four cultivars in a grass mix, allowing for 14kg/acre of seed.
When selecting a grass seed mixture specifically for grazing, look for cultivars from the Department of Agriculture, Food, and the Marine recommended list with high digestibility values, medium leaf white clover for cattle.
In contrast, for sheep grazing, consider a small leaf size with white clover. The criteria for grazing also includes 35/50% tetraploid for dry soils. Otherwise, on heavy soils, look at 15-20% highly persistent tetraploids.
Alternatively, If you are considering a reseed for silage, cultivars with high silage yields are optimal. Another crucial aspect of the reseed mixture includes incorporating 40% tetraploid. Exclude poorly persistent tetraploids.
With grass being the predominant feed source 365 days a year, reseeding is a valuable on-farm investment that you should consider for future returns.
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