A leading grassland expert has suggested that significant numbers of sheep and other livestock farmers cannot identify perennial ryegrass and other common grasses within a sward, if asked to do so.
Charlie Morgan, the man who heads up GrassMaster consultancy, made the point during his presentation to the first of the 2022 College of Agriculture, Food and Rural Enterprise (CAFRE) Virtual Sheep Conferences.
“Grazing swards for sheep should contain at least 50% perennial ryegrass varieties; the equivalent figure for silage swards is 70%," he explained.
"As we look to the future there will be a need for other grass species including timothy, cocksfoot and fescues.
“There will also be a role for herbs in future grassland swards.”
But according to Morgan, sheep would rather starve than eat lower quality grasses. This is why it is not possible within certain sheep grazing scenarios to have swards grazed down to cover values of 1,500kg of dry matter (DM) per hectare (ha).
Clover in a sward
He went on to highlight the critically important value of clover in swards grazed by sheep.
“Clover both fixes nitrogen [N] and improves soil structure. Having a clover cover of around 30% in a sheep sward is recommended. At this level of inclusion, the legume will fix up to 150kg of N/ha per annum," Morgan said.
“Soil is the most important resource on any farm. The problem is that many sheep farmers don’t tend to think about soil until after they have made a mess of it.
“The chemistry of the soil will deliver plant growth. But to make this work requires that the structure of the soil and its biology are also in harmony.”
Research
Morgan confirmed that sheep farmers are not big nitrogen users.
“This predisposes swards to the ingress of weeds, such as buttercup. As nitrogen usages falls on UK and Irish farms, sheep farmers will have no option but to accept the presence of these grassland weeds," he said.
"But total ground cover within a sheep sward must total at least 90%.
30 years ago Morgan was the lead in a unique sheep grazing trial, hosted by the then UK Ministry of Agriculture, Fisheries and Food at a site in the Brecon Beacons National Park.
The land used for the work was 1,400ft above sea level. Prior to the trial commencing the fields had been managed in the same way for the previous 25 years.
Perennial ryegrass and creeping bent were the predominant grass species in the swards at the outset of the research.
The project comprised a series of trials, which compared the impact of five low-input management systems, relative to a standard baseline treatment.
This comprised the addition of lime (as based on a soil test result) plus phosphorous (P), potassium (K) in tandem with 150kg of N fertiliser per ha.
The other plots would see these nutrients gradually removed with the final plots receiving zero nutrients.
A range of sheep grazing and cutting regimes were also built into the project.
According to Morgan, the research confirmed that reducing nutrient input levels will have an equivalent impact on ryegrass tiller numbers within swards.
“Eventually, ryegrass will disappear altogether,” he explained.
“Meadow grass populations mirrored the same situation. Over the 20 years of the trial it was obvious that sheep farmers can control the botanical makeup of their swards by changing the mix and levels of the various nutrients that are applied.
“Significantly creeping bent plant numbers increased in relative terms within a sward as applied nutrient levels fall. This has a major impact on the sward and its ability to deliver real animal performance.
“Of equal significance is the fact that sward density falls off dramatically as applied nutrient levels diminish. And this has a major impact on the ability of swards to sustain ewe and lamb productivity.”
