Red clover is key to high protein forage
Red clover can out-perform its white sibling but concern over grazing, persistency and vulnerability to diseases remain, delegates at the recent British Grassland Society/Silage Advisory Centre’s Profiting from Red Clover workshop were told. Simon Wragg reports.
FOR host farmers John and Tim Downes, red clover is key to providing a vigorous, high protein forage on their 260-hectare (650-acre) organic farm at Longnor, south Shropshire.
“Initially Tim wanted it to provide two cuts of silage to mix with other clover silages in the pit, for the 180-cow milking herd, while I wanted it for my Aberdeen-Angus finishers,” said John, president of the British Grassland Society (BGS).
“We aimed to have three cuts this year but rainfall of just 14 inches is half of the norm. On our sandstone and boulder clay soils we’ve had just 1.5 cuts; not even the drought of 1976 was like this.”
Tim added grazing management had become a challenge. “Even with a plate meter to measure covers the only way we’ve been able to keep grass in front of stock is by losing mouths.”
In grazing fields red clover stands out thanks to its deep, thick tap root among prairie-like swards. Facing a forage shortfall for this winter re-emphasised the need to ensure all material cut for silage ended up in a bale or the pit, delegates were told.
To protect clover’s fragile leaf, the Downes’ use a mower fitted with two driven rubber belts behind the cutting head through which all material passes.
“Compared to other designs this doesn’t damage the crop as much”, said John.
He said it was essential a cutting height of 6-7cm was adhered to, to avoiding damaging red clover’s crown which could kill off the plant entirely.
Leaf shatter and loss when being picked up by the forager was another area of concern. Rowing up when the morning dew was still present could help protect the fragile leaf, explained David Davies of Silage Solutions.
In all cases he advised growers to use an inoculant or chemical treatment to ensure good fermentation. “Red clover has insufficient sugars to fuel a quick, thorough fermentation and its high protein content increased buffering. That’s important for later cuts where the proportion of red clover to grass will be higher.”
Dr Davies also advised avoiding products containing heterofermentative L.buchneri and L.brevis as these were not necessarily good for legume fermentation. Instead, he said to look out for homofermentative L.planatrum or L.pediococci.
Delegates were also warned to ensure dairy cows did not gorge on the highly palatable red clover crop by offering a buffer before turnout after milking to avoid bloat.
Likewise, red clover’s relatively high level of phyto oestrogens meant ewes should be kept off for six weeks before and after tupping.
But red clover silage was rocket fuel for finishers, according to John. “When I told our Dovecote producer group I finished our cattle on it without concentrates they couldn’t believe it.”
Managing nutrient requirements
RED clover, like white clover required a firm, fine seedbed for good establishment with a soil pH of six and no water-logging, but nutrient requirements differed, explained George Fisher, BGS project manager.
“A phosphorous index of 2 and a potash index of 2- is the target for red clover”, he said.
“For the growing crop it requires 100-150kg/ha phosphorous and 250-300kg/ha potash where taking 11-13t/ha off in three cuts. And no inorganic N at all - this is not white clover.
“A 6 per cent DM cattle slurry applied at 2,700gall/acre by dribble bar immediately after silage ground had been cleared would avoid smothering red clover and supply 80kg N, 55kg phosphorous and 260kg potash.”
He said studies by SAC suggested red clover in a typical grass/clover ley supplied 150kg N/ha (60kg N/acre) in its first year, 90kg N/ha (36kg N/acre) in year two and 50kg N/ha (20kg n/acre) in year three. This was drastically reduced where artificial N was also applied to the ley.
“Remember every kilo of N fixed by the crops is worth £1 at today’s prices for artificial N.”