Across the Thrive programme, like most beef farms, there has been an increased interest in both multispecies swards (MSS) and increasing the overall contribution of clover to swards in order to reduce the level of chemical nitrogen needed in beef systems.
Within the programme, the main focus has been on the latter of these two options as many beef farmers are reluctant to sow large areas of MSS just yet, while questions around persistency are still to be answered.
This is why it is important for the likes of Tullamore Farm (page 51), UCD’s Lyons Estate, Devenish’s farm at Dowth, as well as Teagasc research farms across the country to carry out the work they have currently in place to test MSS in an Irish context with the lessons learned used to educate farmers in the best approach and application of MSS for the future.
What seems to becoming clear from trial work in various locations is that stock need to be maintained on the MSS so that the microbes in the rumen have time to adjust to the new diet.
Grazing stock on MSS for part of each grazing rotation is not an option as the microbe population will be in a constant state of conversion. Therefore, when introducing MSS to a farm it needs to be a significant enough area to at least maintain one stock group for the majority of the time.
Many of the Thrive farmers, for now at least, are therefore looking to clover (more so white than red), for reductions in chemical nitrogen usage.
It would be hard to question this approach when looking at data from Teagasc Grange where they are comparing perennial ryegrass swards with grass/clover swards and MSS swards, across varying nitrogen input levels.
At 0kg fertiliser N/ha on the clover (10.5t DM/ha) and MSS (11.5t DM/ha) swards out yielded the ryegrass sward with 0kgN/ha, which yielded less than 6tDM/ha and at 120kgN/ha which grew 9.5tDM/ha.
This shows the potential of these swards but also that the majority of the benefits in herbage production being realised are coming from the clover inclusion in the sward.
Yes, MSS offered further benefits when the mix is optimally formulated but we must remember that grazing management practices need to change more so with MSS than with current practices with grass, grass/clover swards and currently there is a knowledge gap in this area.
To introduce more clover to swards, a number of the Thrive farmers have used some form of oversowing carried out predominantly in April and May.
Some of the farmers have plans for reseeding and oversowing but are trying to correct soil nutrient deficiencies prior to seeding, as to do so without correcting soil indexes would be a waste of money and effort.
Conditions at sowing need to be ideal
In truth, speaking to the farmers in the following months after oversowing, results are quite variable. Many have described the results as patchy, or maybe very good in one field that they did and non-existent in another.
Conditions at sowing need to be ideal. Sow too early in spring and you risk a night of frost hitting newly established seedlings, while sowing too late there is a risk of hitting a dry period and the young plant not receiving sufficient moisture is a concern.
Sowing method or, more so, sowing depth is very important. The clover seed is much smaller than a grass seed and therefore has a smaller energy reserve in order to establish itself. Ideally, a clover seed should only be 10mm to 12mm deep. Where broadcasting seed, soil-to-seed contact is very important and therefore a run of a tine harrow or roller or a light application of watery slurry will help to get seeds in contact with the soil.
Management of the sward for the remainder of the year then needs to be perfect to encourage good establishment of the clover seed. This suits dairy-beef systems in that calves can be used to graze these swards at lower covers for the remainder of the year. Ideally, this is between 1,100kgDM/ha and 1,200kgDM/ha (8cm to 8.5cm pre-grazing sward height).
Where incorporation of white clover has been most successful is where a full reseed has been undertaken, using both full plough and min-till methods.
This reduces the competition at establishment and allows the clover to strike at the same time as the new grass.
Obviously this comes at a greater cost to carry out but with more positive results, it is likely the best long term approach for many beef farmers.