Conserving Forage: Hay, silage and deferred grazing
(Photo: PfL certified Cotswold Beef)
By Pasture for Life Research Officer Charlotte Wheeler
Haymeadows have been a well-established feature of landscapes in the United Kingdom for over a thousand years, with 8 out of 10 of the settlements in the Domesday book recorded as featuring hay meadows. As late as 1970 about 80% of conserved forage was conserved as hay but by 1990 this had declined to 30% as silage making grew in popularity. This, along with the more general intensification of farming practices in the United Kingdom, has had a significant impact on biodiversity (see previous article).
‘Semi-natural grasslands and species rich pastures, i.e. hay meadows and pastures that are not intensively cultivated or fertilised, evolved as a result of centuries of low intensity farming and comprise of native strains of grasses and flowers. They can be among the most species-rich ecosystems in the world.’
The shift away from hay in favour of silage is due to several factors. Haymaking requires roughly four to five days of dry weather to allow proper desiccation and to prevent rotting when baled – in contrast, haylage and silage is wrapped when still slightly moist (which allows fermentation) and so is a more flexible way of preserving forage when the weather might not allow for full drying.
Silage making also allows for large acreages to be harvested in a shorter amount of time, with fewer staff. Due to being harvested when less mature and subsequently fermented, silage has the potential to have a higher protein content than hay, making it more appealing in more productive systems.
However from a biodiversity standpoint, because silage is typically cut earlier in the season than hay it can reduce the plant diversity of a field, as later flowering species are unable to set seed. It also reduces a field’s ability to provide fodder and shelter for other invertebrate and animal species.
More intensive systems may see inorganic fertiliser applied to grasslands to allow for several cuts of silage to be made throughout a single season, further reducing their ability to provide food and shelter for wildlife species. “Improved” pastures will typically have been ploughed and re- sown with vigorous, productive species such as ryegrass and white clover. These practices are incompatible with the maintenance of species-rich grassland.
(Photo: haymeadow at PfL certified Essebeare Farm Devon)
Hay meadows have numerous benefits for biodiversity due to many of the factors outlined in our most recent post on the biodiversity benefits of low-input grazing systems. These chiefly arise from taller, more mature pastures which provide habitat and forage for the insects, birds, and other wildlife species who depend on them.
‘Increased vegetation height was observed on PfL farms, which is known to be beneficial for biodiversity ranging from invertebrates, such as butterflies and bees, to mammals and birds. Vegetation height was also positively associated with soil moisture, C, N and total invertebrate abundance.’
Recent estimates of hay meadows made according to traditional methods indicate that there are now less than 1000 ha in England, which are largely confined to the Uplands of Northern England, and less than 100 ha in Scotland, although the total amount of hay made is larger.
The enclosed hay meadows, in tandem with other components of the upland landscape, provide important nesting and feeding habitat for various waders, notably redshank, lapwing, snipe, oystercatcher and curlew. In addition, passerines, such as yellow wagtail, skylark, meadow pipit, linnet and twite, are closely associated with hay meadows either for feeding or breeding (1).
(Photo: PfL certified New Holland Farm, Orkney)
Research looking at the best management options for hay meadows found that the traditional time for hay-cutting (late July) results in more seed (2) than a June cut, producing nearly equal amounts of forb and grass seed. The earlier cutting date associated with silage making reduces the quantity of seed shed when compared with later cutting for hay.
The tedding and field drying of the mown grass crop during hay-making is important for ensuring that a large portion of the total available seed is shed back onto the pasture. Later season aftermath grazing of areas mown for hay also serves a role, creating some structural diversity in a mown area, and by providing dung for insects.
Another review paper looking at conservation management of upland hay meadows explored the effects of the restricted working of the grass crop associated with silage-making, finding that it reduced the populations of species that rely on regeneration from seed (3). They concluded that species richness is maximised by management involving spring and autumn grazing, a mid to late July hay cut, no inorganic fertiliser and minimal levels of farmyard manure.
A number of Pasture for Life members are practicing a further option by reducing their area of conserved forage in favour of deferred grazing i.e. leaving an area out of the grazing rotation from mid-summer as with hay making, but subsequently grazing, rather than mowing it. Not only does this deliver the biodiversity benefits of a late hay cut, it also reduces the costs associated with hay and silage making, such as diesel.
For those farmers who rely on contractors to cut their hay, increasing the proportion of deferred grazing may be beneficial from a cost savings perspective in that it reduces reliance on, and competition for, contractors. Feeding livestock in situ can also play a role in extending the grazing season and reducing overwintering costs. This is being further explored by farmers who are bale grazing (feeding hay bales unrolled on pasture) on deferred grazing as an out-wintering strategy.
‘There are a many different reasons for giving bale grazing a go. It can offer a low risk, yet much cheaper overwintering option for many beef farmers, using less labour, less machinery and less fuel.’
(Photo: bale grazing at PfL certified FAI Farms, Oxfordshire)
Rotating which fields are left to deferred grazing each year can change or increase their diversity; fields which are cut or grazed at the same time each year may have a more predictable species composition than ones which are grazed at different times or allowed to set seed periodically.
Deferred areas can also serve as a useful “backup” for a farmer who is short of grazing during their ordinary rotation, such as during periods of prolonged drought when pasture growth may have slowed. Deferring grazing rather than cutting it for hay may also be beneficial in drought periods as tall pasture protects soil better compared to a recently mown, more exposed acreage.
The benefits of taller pasture covers, whether mown for hay, left for deferred grazing, or simply as part of a long grazing rotation, are well-evidenced. Every farm business will need to make decisions about their winter feeding regime within the context of their system, but there is no doubt that when we look at the system from a biodiversity point of view, deferred grazing and using hay instead of silage can deliver important benefits.
(Photo: haymaking by PfL farmer Jeff Glyn Jones)
Bibliography
- Brown A, Grice P. Birds in England by Andy Brown Phil Grice – AbeBooks [Internet]. 2005
- Smith RS, Pullan S, Shiel RS. Seed shed in the making of hay from mesotrophic grassland in a field in Northern England: effects of hay cut date, grazing and fertilizer in a split-split-plot experiment. J Appl Ecol U K [Internet]. 1996 [cited 2024 July 15]
- Jefferson R. The conservation management of upland hay meadows in Britain: A review. Grass Forage Sci. 2005 Nov 11;60:322–31
