Farmers considering a multispecies sward (MSS) should establish the new ley in a spring reseed, a grassland expert has said.
“Spring reseeds work best. Fields bested suited to MSS should have a low weed burden, pH between 6.3 and 6.5 with soil temperatures above 12°C,” outlined Dr Mary McEvoy during a webinar hosted by Germinal. “You can potentially sow out a multispecies sward up to the start of August. But after this point, day length is getting shorter. Soil and air temperature tends to be lower as autumn approaches and the chance of a successful reseed is reduced,” she added.
For weed control, using a post-emergence herbicide is not an option as this will kill the herbs and clover in the new MSS.
“Weeds should be controlled in advance of reseeding. A full ploughed reseed is recommended as the herbs are quite vigorous and can out-compete the usual grassland weeds from a clean seedbed,” she said.
Data from the Germinal trial site in Wiltshire showed that MSS with six to eight species were the optimum seed mix in terms of yields, persistency and cost.
However, the data showed the performance of well-managed ryegrass and white clover swards did compare favourably to the MSS, yielding close on 19t DM/ha in 2021. Chicory and plantain are normally the dominant herbs included in MSS, but persistency is an issue.
According to McEvoy, trials for MSS established in 2020 showed that chicory and plantain accounted for almost 75% of the new sward composition in July. This slipped to approximately 60% by September as clover and ryegrass content increased.
But in year two, both herbs were down to 30% of sward composition by July and less than 25% by September 2021. During the same time, white and red clover increased to over 50% of the sward.
Clover content also increased when nitrogen application was reduced from 250kg to 150kg/ha, yet sward yield was unaffected.
Outlining the role of MSS on livestock farms, McEvoy said they are best suited to grazing. “They can be cut for silage but need wilting for at least 48 hours. A new MSS is ready to graze when chicory has produced seven leaves, plantain has produced six leaves and the sward can withstand the pull test by hand.
“A MSS should be rotationally grazed, with stock on the sward for a maximum of three days, and at least 25 days left between each grazing. Do not overgraze. Leave a higher residual around 6cm.
“Tactical nitrogen can be applied in early spring, but stop by May as this will reduce the contribution from clover,” she said.