Sales of white clover in grass mixtures were reported by some seed companies to be 5 per cent down last year. Sara Gregson finds out why.
Varieties of white clover have been widely sown in the UK since the 17th century and its popularity derives from its many benefits. These include nitrogen (N) fixation (up to 100-150kg of N/ha generated), increased animal performance through greater intakes, and improved feed value – white clover is more digestible and has higher protein and mineral content than grass-only leys.
The creeping and rooting style of white clover growth can also help tackle soil compaction by aerating the surface layer and it has a complementary growth pattern to grass; slower to get going in the spring, waiting for soil temperatures to reach 8°C, rather than 5°C for grass.
Clover grows strongly in mid and late summer and fills the gap when grass growth often falls away.
With so much going for clover, it is hard to understand the reasons less was sown last year but Rod Bonshor, general manager for Oliver Seeds, thinks he knows why.
“White clover is an incredibly useful addition to any grazing mixture but has one downside,” he says. “It is a broad-leaved plant and therefore susceptible to most herbicides used for perennial weed control. Farmers have to choose between the level of weeds they are prepared to accept and the contribution made by the clover. If the infestations are too high, spray and re-introduce more clover later.
“Long, wet springs are not kind to clover. The plants can be overpowered by grasses early on, leaving the slower-growing clover open to slug attack, with reduced chance of recovery once the grass canopy gets too tall. White clover populations were dramatically reduced after the dreadfully late spring last year.
“There has also been a rise in damage by the Sitona weevil, particularly in the east of the country, which makes bite-sized notches in white clover leaves. This has led to a lot of damage and reduction in clover vigour. These may have also affected farmers’ decisions about sowing clover last year.”
Independent grassland consultant Dr Liz Genever says using a break crop between old and new leys is a good way to clear a field of problem perennial weeds before sowing grass/clover mixtures. However, in an AHDB reseeding survey carried out in May 2016, only 8 per cent of farmers were doing this.
Dr Genever says: “Some farmers decide to get the grass mixture in, deal with any seedling weeds by spraying the new leys, then aim to stitch in clover later – at the safe time to do so after treating. But actually some forget, conditions do not come right, or they are busy doing other things when the time comes.
“It might be worth sowing a mixture with clover already added in, as this is likely to be cheaper than buying clover on its own later. If it comes well, that saves on the cultivation costs and time spent incorporating it afterwards. Or, if weeds do come up, these might be spot treated or sprayed using a weed wiper to protect the clover.’
Dr Genever has also seen fields where clover dominance is a problem – often on beef and sheep farms where late silage or hay has been cut in late May/early June. This allows light to fall on to the stolons and the clover takes off outcompeting the grass.
“In these cases, farmers should apply some more nitrogen fertiliser to help the grass become more competitive, or graze it hard in the winter with sheep which will damage the stolons, halting growth the following year."
Last summer, sheep farmer Tim Heywood at Highfield Farm, Rackenford near Tiverton in Devon, overseeded an old 2.8ha field of permanent pasture with white clover and Lofa festulolium.
Conditions were tough in the summer drought, but the results have been impressive.
“We have been on the farm for three years and have improved the grassland for our flying flock of 400 ewe lambs, which we run for 11 months and sell as shearlings in the autumn,” explains Mr Heywood.
“This field had a lot of weeds so we sprayed with the broad-spectrum herbicide Forefront T in 2017 and grazed it for the rest of the season. Last summer we decided to add a mixture of 3.6kg/ha of Buddy white clover and 22kg/ha of Lofa.”
The sheep grazed the pasture hard before harrowing in two directions to pull out all the dead thatch.
The seed was added into the tined seeder and broadcast in two directions before being rolled with a heavy set of 6m wide Cambridge rollers. Mr Heywood drove slowly in both directions, allowing the sharp edges to push the seed into the ground. The sheep stayed in the field until the clover started to germinate to keep the original sward tight to allow light to the seedlings.
“I had reservations about seeding because it was so dry,” admits Mr Heywood. “But the clover came through strongly across the whole field.
“I took a cut of haylage in August and the sheep grazed it into the autumn.
“This spring it is easy to spot the young Lofa coming through and I am expecting the clover to get going once the temperatures rise. This has been a cost-effective way to improve this field.”