How to Rewild

Grassland Management

HomeGuides

Grassland Management
Management Guide

Contents

The kind of grassland you’ll find on your property will depend largely on your soil type, pH, and the history of your land. Acid Grassland soils have a pH below 5.5, Calcareous Grassland are their opposite, with a pH over 6.5 on lime-rich soils. In middle are Neutral Grasslands, with a pH between 5.5 to 6.5.

But some grasslands have been heavily altered by humans. These Modified Grasslands have a fairly neutral pH, though the soil may have been neutralised by the application of lime. The fertility has been enhanced over time by enrichment with artificial fertilisers, muck spreading, or other sources including dog excrement.

All types of grassland are used for grazing, though modified grassland is the most productive. Modified is also most widespread, making up as much as 3,000,000 hectares in England alone, compared with 800,000ha of Calcareous, 700,000ha of Neutral and just 300,000ha of Acid Grassland (not including Bracken).

These figures don’t include temporary grassland, in the form of clover leys, which are an important part of crop rotation cycles in many arable systems. It’s estimated that this combination of temporary and permanent grasslands covers nearly half of the UK’s land area.

Grassland Management Overview

This article is a summary of what you’ll need to know when managing grassland. While there is an awful lot of information here, we’re really just scratching the surface of a very complex topic.

To summarise this summary, the key points are:

  • Different livestock species, breeds, sexes and ages graze differently
  • Grazing creates more diversity than mowing
  • Nitrogen levels in soil tend to fall slowly over time if the land is grazed and/or mown
  • Hemiparasitic plants mask the effects of high nutrients
  • Cutting once annually is enough for healthy grasslands – late June to July; unhealthy grassland can take two cuts per year
  • The later you cut, the lower nutritional quality the grass, but the better it is for biodiversity (April is great for silage production, August for wildflowers)
  • Some grasslands have special conditions – these may require unique management regimes

For those who want to get their goggles on and take a deep dive into grassland management (including specific breeds of livestock), we’ve pulled together this 469 page PDF. It’s the most useful parts of Natural England’s ‘Lowland Grassland Management Handbook’ – you can find the full guide (including Chapters 1, 16, 17 and the appendix) on their website.

What Can a Grassland Produce?

A grassland isn’t just a place to graze livestock, though that can be a valuable source of revenue. It’s also possible to combine this habitat with other services and production systems, to create more value.

  • Meat, dairy
  • Petting zoo, model farm, farm tours
  • Camping/glamping
  • Livery (equestrian facility), dog field (fenced, private access)
  • Wildflower seed production
  • Silage production
  • Orchard
  • Events (weddings, corporate days, fairs, festivals, markets etc)
  • Cover crop / green manure (particularly with leguminous plants)
  • Playground, eatery, festive trail (e.g. Halloween, Easter)
  • Agroforestry (fruit, nuts, timber grown in-field)
  • Viticulture (grapevines)
  • Caravan / boat storage
  • Overflow parking, airport parking (with grass protection)
  • Skills workshops (traditional crafts, foraging, farming etc)
  • Natural burial
  • Solar and wind energy
  • Allotments (habitat lost to Arable/Horticulture)
 

Not all of these systems are of equal value to biodiversity, and some, like silage production and allotments, may degrade the ecosystem over time. This doesn’t necessarily mean that the land will reduce in productivity – higher nutrient levels may result in larger harvests. But the artificially-high levels of nutrients in the soil may take decades to remove if you wish to restore the habitat to a healthy grassland ecosystem after these uses.

Orchard
High intensity orchard on heritage land - this could be higher productivity if also grazed by sheep and/or cattle rather than mown.

Grassland is Temporary

Without management, the neat and tidy Modified Grassland and Clover Leys found in most farms and gardens will revert to scrub. This is the typical pattern of succession that you’ll see:

Cultivated Lawns – neat and emerald green, short-cropped turf which is high in available nutrients.

Seed-rich Grassland – the original state of wild grassland habitats, with taller seedheads mixed in. On land succeeding from arable, this habitat is dominated by agricultural weeds like ragwort, dock and thistle. On lower nutrient patches, there is a more diverse community of wildflowers.

Low Scrub – scrub encroaches from the edges, and isolated bushes pop up in the grassland, from bird droppings. The boundary is less well-defined as linear hedgerows become bushier.

High Scrub – the grassland closes over and this habitat is effectively lost except for a few glades and animal tracks.

Of course, this doesn’t happen exactly the same way in every habitat – in some, planted trees may cause woodland to appear before high scrub appears. And in certain parts of the country, repeated flooding, severe exposure, toxic soils or altitude can restrict tree and scrub growth. However, as a general rule, without intensive grazing, a diverse guild of herbivores and/or scrub management, grassland will eventually succeed to scrub.

Calcareous grassland
Calcareous grassland succeeding to scrub in the absence of grazing on a limestone headland - the former site of a golf course.

Livestock vs Mowing

As grasslands are a fragile system, which only exist due to grazing pressure, the importance of livestock cannot be overstated. While mowing is fine in the short term, in the long term there’s just no substitute for the physical disturbance, random grazing, and fertilising that you get with an animal.

There’s a big difference between grass clippings and manure, too – the latter affects the soil pH and provides a more concentrated form of nitrogen in tiny spikes, at intervals across the habitat. There’s also the benefit that when dairy and/or meat products are produced from the animals, this means nutrients are exported off the land, offsetting the excess in nitrogen from atmospheric deposition.

Livestock Units

But getting the right density of grazers can be tricky, and it relies on the ‘livestock unit’ (LU). One LU is not always the same as one animal, because some animals have a larger impact than others. For example, a deer has twice the grazing impact of a sheep. Here is a useful reference table for livestock units (figures combined from multiple sources):

1.0 LU – Cattle (aged 2y+)
1.0 LU – Horse
0.8 LU – Pony / Donkey
0.6 LU – Cattle (aged 6m – 2y)
0.3 LU – Red deer
0.15 LU – Sika deer / Fallow deer
0.12 LU – Goat
0.12 LU – Lowland ewe and lamb / Ram
0.08 LU – Store lamb, Hill ewe and lamb / Hogg / Teg
0.08 LU – Roe deer
0.02 LU – Mountain hare
0.01 LU – Rabbit

Grazing Differently

Larger animals tend to have a bigger impact on the soil, as they can cause compaction, whereas smaller animals tread more lightly. However, the way that animals graze also differs not just from species to species but between breeds, age classes and sexes. 

For example, sheep bite off short grass just above ground level and are very selective eaters, while cattle prefer longer grass and take bigger mouthfuls. Soay ewes may browse more scrub and trees, while rams prefer grasses, and some breeds like Hebrideans are more accustomed to scrub control.

Finding the right breed for your land can make all the difference to how the ecosystem develops over time. This is a very site-specific problem, and the detailed PDF from Natural England linked below may help, but you can also get assistance from the Rare Breeds Survival Trust, which has plenty of useful information available on their website. Rare breeds are hardier, and require less veterinary attention – they may also produce more premium meat products.

 

Sheep pasture
These 11 sheep have roughly the same grazing pressure as 1.3 horses, but more legs.

Restoring Nitrogen-Enriched Soil

If you’ve got lush, emerald green grass, then you’ve likely got Modified Grassland – it’s a degraded habitat that is dominated by rye grass. This ecosystem is typically of low value for biodiversity, so ecologists and nature enthusiasts tend to get very passionate about restoring wildflower meadows on these sites.

When nitrogen fertiliser (artificial or muck spreading) is sprayed onto to grassland, its effects last far beyond the initial application. The soils and plant community can continue to be degraded for at least a decade, and even 25 years after the last treatment. Some landowners may wish to try and reduce the nitrogen levels present in their soils, to help re-establish a more biodiverse grassland habitat.

However, there is a lot of disagreement in the ecology community about which strategy is most effective for dealing with nutrient rich grassland. Researching this topic in detail uncovered that the evidence for each technique is mixed and sometimes contradictory. Some methods may be acting as placebos – over a long time period a more diverse grassland community naturally becomes re-established if no additional nitrogen is added.

Atmospheric Pollution

In intensive farming regions, can cause significant nitrogen pollution. 

Fertilisers’ effect are complicated by atmospheric nitrogen pollution, which has mainly been decreasing since the late 1980s, though levels are still high. It comes from fossil fuel emissions and emissions from agricultural processes like fertilising fields, with reactive nitrogen deposited on grass in rainwater.

This higher than normal background deposition rate means that, without an output, some ecosystems may accumulate nitrogen over time. This is particularly the case downwind of intensive livestock farms, where reactive ammonia is more likely to be released.

Removing Inputs

The simplest way to reduce nutrient levels.

When soil nutrient levels are higher than in nature, nutrients tend to leach out of the system over time, becoming washed away and taken up by plants. That’s why farmers re-apply fertilisers every year – to reverse these losses. So, rather than putting effort into outputs, it is often more effective to first focus on removing and mitigating any artificial inputs.

These inputs may come from sources you might not expect, like supplementary feeding of livestock (e.g. grain troughs, imported hay bales), nutrient-enriched floodwaters, and runoff from neighbouring farms. By avoiding fertilisers and muck-spreading, stopping or reducing supplementary feeding in the field, and preventing incoming runoff, you should see a slow decline in soil nutrients. However, it is possible that there may still be another input which hasn’t yet been identified, like high atmospheric deposition or even dog excrement!

Grazing

Typically reduces nutrients over longer time periods.

In most pastures, grazing with livestock should reduce nitrogen levels over time, for a few different reasons. The animals will excrete nutrients into the soil – these pass through the plant layer and leach into groundwater, where they’re carried away. Nutrients are also released as volatile compounds into the air from dung, breath, and other gaseous emissions. Finally, the nitrogen is taken off the field in the form of animal products like wool and milk; and also in their meat.

The size of these outputs varies a lot depending on the livestock, site, soils, climate etc. Grazing off the nutrients is slow but steady, and creates biodiversity along the way, as the grassland will be more varied in height than if you use a mower. This beneficial effect is known in ecology as ‘selective defoliation’ – some plants are eaten more than others, and some areas are left longer than others, creating diversity.

Grazing also has the added benefit that it ‘masks’ the effects of nutrient-enrichment – cattle prefer eating taller, dominant plants like grasses, allowing shorter wildflowers to get established, provided that the area isn’t overgrazed. 

Mowing

A very slow impact, with mixed results for biodiversity.

Over a decade or two, you’ll usually find that consistent cutting and removal of hay (especially alongside grazing) should reduce the available nutrients in the soil and create a more diverse grassland community.

However, in the short term, frequent mowing can create more vigorous grass growth, especially if the ground is rich in nutrients. It may also encourage shorter, nitrogen-enriching plants like clover to thrive.

Mowing always removes some plant seed heads before they have a chance to scatter onto the soil. It’s a balancing act, finding the right timing and frequency – twice a year is typically recommended for nutrient-enriched sites – less frequently for healthier grasslands. The hay must be removed each time, not just from the surface, but from the site, to prevent a steady build-up of nutrients and choking-out fresh growth.

Turf / Sod stripping

Removes nutrients but damages biodiversity.

This is the nuclear option, though it does work! Given that nutrients are concentrated in the topsoil, removing the topsoil will of course remove the nutrients. This method works extremely effectively, but it also comes with some very significant downsides:

  • The soil must be disposed of, creating a new issue at another location
  • Bare ground has high susceptibility to erosion
  • Removal of the topsoil also removes much of the native seedbank
  • The soil ecosystem can suffer degradation which persists for at least 3 years after the work
  • As exposed soils dry out, they tend to lose organic matter and carbon
  • Strip removal will create regular patterning which could be visible for decades
  • If done across large areas, plant reestablishment may be slow
  • Some soils may not be deep enough for this treatment
  • Biodiversity both above and below ground will be destroyed, including hibernating invertebrates, butterfly eggs, mammal nests etc

 

Hemiparasitic Plants

Restores biodiversity but increases nutrients.

Certain types of plant, which are native to British grassland ecosystems, suck nutrients from the roots of grasses – these plants, which include Eyebrights and Rattles, are called hemiparasites. Rather than reducing nitrogen in the soil, they mask its effects, and may even increase nutrient loading. But they have a much less physical impact on an ecosystem than any of the other options. In fact, they are a good alternative if there are sensitive invertebrates and ground-nesting birds which need protecting.

While nitrogen levels in the soil may increase, the vigour of the grass itself is knocked back, allowing wildflowers to take hold. However, the sward will get too deep, and scrub will encroach unless moderate levels of grazing or mowing also accompanies planting of hemiparasites.

These plants are annuals, so they will need to set seed successfully every year, if the next year is to be a success. They are also hard to establish, as relatively-expensive fresh seed is required, sown on scarified soil, with the grass kept short enough for them to become established (with mowing or grazing). On very nutrient-rich soils, grasses may choke out the growth of hemiparasites like Yellow Rattle, which struggle to get enough light once the sward height is too high.

Yellow Rattle
Yellow Rattle is a hemiparasitic plant which sucks nutrients from the roots of grasses, encouraging more diverse wildflower growth.

When to Cut - Different Mowing Regimes

Depending on which product you’re hoping to farm, there are a variety of different strategies for managing grassland, which involve cutting at different times of year and/or grazing.

Spring Silage

Silage is effectively pickled grass, which is harvested and then allowed to ferment for a few months before consumption. It tends to be produced on grassland which is fertilised, and may be oversown with rye grass and leguminous plants like clover to enhance nutritional value. Farmers cutting for silage typically do so at least twice per year – once from late April to mid May and again six weeks later. 

Silage production has a negative impact on biodiversity, by enriching the soil nutrients and cutting wildflowers at a sensitive time of year. However, the machinery used to gather the grass crop – forage harvesters – can also be repurposed to remove grass when landowners wish to remove it for nitrogen reduction purposes (see above).

Summer Hay

As the season progresses, the grass harvest will becomes less digestible, until seedheads are produced, at which point it is low quality forage. So, grass is typically cut for hay in June or early July in lowland areas, though this varies by region. The grass is left out on the field to dry, before being rolled into large cylindrical bales by machine. An alternative method is manual raking, stacking the arisings into haystacks, though this is hard, sweaty, time-consuming work!

The earlier cutting date of silage makes it more nutritious as winter supplementary feed, but hay is better for the ecosystem, as it avoids disturbing plants during the flowering period. However, late-flowering species like Fleabane may suffer, as a June or July cut can knock them out just before peak pollination season. On nature reserves, hay may be cut later than on agricultural land – even as late as September in some places.

Experts recommend varying the time of your cut across the project where possible, and leaving some patches uncut from one season into the next. These will become ‘rank grassland’ and the flowers and grasses will collapse over winter, creating a deep layer of leaf litter, which is valuable for small rodents and invertebrates. A mosaic of rank and short grassland may sustain the most biodiversity over time.

On fields which have been unmanaged for a while, the rank grassland may attract Kestrels and Barn Owls, due to a superabundance of rodents. However, this style of management chokes out low-growing wildflowers, creating low light, dank conditions at ground level. This can be particularly risky for annual plants (which grow from seed every year), which are seriously knocked back by one bad season.

Aftermath Grazing

While cutting for hay and silage can be a useful way of keeping grassland growth in check, and restricting some scrub encroachment, it isn’t ideal for plant diversity. Grazing at moderate levels can open up the sward, disturbing the soil, adding patches of nutrients where dung falls and eating back dominant plants. This disturbance creates new opportunities for seeds to germinate, and lets light down through denser grassy growth, to reach the wildflowers at ground level.

The many benefits of grazing mean that landowners may combine this strategy with mowing, in a system known as ‘aftermath grazing’. This typically occurs after the summer harvest, which is taken in June or July, and grazing will continue until November (or until the ground becomes too soggy to allow it).

However, when grazing, it’s important to avoid poaching of soils – this is when the ground becomes compacted and oxygen-deprived (anaerobic). Puddles tend to form on the surface, creating a hard pan, which resists the growth of plants. Some poaching around ponds and scrapes is natural, but it’s not usual to find it in grassland. 

Silverweed is a useful early indicator species which tends to pop up when the ground is compacted and approaching the point of poaching – the silvery, fern-shaped leaves and yellow flowers are easy to identify. Native yarrow and non-native chicory can be sown to break up compacted soil – they are also valuable as part of a grazer’s diet.

If you don’t have livestock, you can imitate their behaviour in the aftermath period by lightly cutting patches of the meadows throughout late summer and beyond until March. At this point, the land can be rested, allowing plants to grow vigorously into their flowering season.

Hay bales on a grassland
Traditional hay meadows are cut in late June or July. The later the cut, the less nutritional the hay, but the more biodiverse the grassland.

Managing for Biodiversity

Creating a biodiverse grassland is a balancing act between human management practices and natural processes.

Dung Beetles

A truly healthy grassland community also includes dung beetles, as they incorporate rich manure into the soil. But dung beetles need year-round grazing to thrive and they are killed off by worming medicine in the diet of livestock. Worming cattle offsite can reduce the risks, or mob grazing them, which reduces parasite load and has been found to improve dung beetle abundance. Some plants like Chicory contain effective natural worming agents, so these can be sown as part of a grassland to reduce the need for worming.

Green Haying

Restoring plant diversity is an essential part of rebuilding or creating a healthy ecosystem. The best place to get that diversity is from locally-sourced seeds, but that is a tall order when it comes to meadows (perhaps Habitat Aid is your friend here).

Green haying is a good system for transferring diversity from one place to another. It involves cutting a healthy grassland with the same soil type, in your local area, and, while the arisings are still fresh and green, spreading them across your own grassland. This allows the seeds to pop out into your soil (as they tend to be released from drying seedheads).

This strategy works most effectively when your field has first been scarified, exposing some bare patches of soil for seeds to drop into. This can be done with a chain harrow pulled behind a tractor, a petrol-powered push scarifier, or manually, with a stiff rake and a lot of elbow grease. 

If you aren’t able to identify a suitable site in the local area, speak to farmers and Wildlife Trusts to see if they can provide you with something suitable.

Scything/Brushcutting

The lowest impact alternative to livestock is not mowing, which tends to create a uniform grassland with low diversity, and compacts the ground, but scything. However, anyone who’s tried scything will testify that managing a meadow larger than half an acre in size feels like cruel and unusual punishment. Add to that the importance of raking up the arisings in hot summer weather and it’s a recipe for heatstroke, tantrums or divorce.

A brushcutter is a much more pleasant system to use (though even this has its limits), and battery-powered units are available which, despite the relatively short operating time, are very quiet and less messy. Electric brushcutters allow you to work during cooler summer evenings without disturbing neighbours 100m away. Fitting a metal blade will reduce the potential microplastic pollution and make the system suitable for controlling scrub encroachment.

Bracken Management

On Acid Grassland, Bracken, like scrub, will slowly colonise the habitat over time if left unchecked. By fixing nitrogen and producing prodigious quantities of leaf litter, this large fern can shift the soil quality over time, enriching the nutrients. This degrades habitat quality, as most Acid Grassland species thrive in nutrient-poor soils. 

However, Bracken is a native plant, and is naturally found in these ecosystems. It can provide a home for invertebrates, perches for birds and a refuge for reptiles and mammals. In the past, this plant would likely have been kept at bay by a combination of wild horse grazing and auroch activity. Today, we can replicate this control strategy with wild ponies and cattle. You can find out more about Bracken on its subhabitat page.

Bracken
Bracken has value as a refuge for biodiversity, but like scrub can accelerate succession into woodland.

Specialist Grasslands

There are some general rules to follow for maximising grassland biodiversity; cut later, graze with cattle, avoid supplementary feeding, avoid worming onsite. However, some grasslands are a special case and require sensitive management. 

These special habitats will often be recognised with an SSSI (Site of Special Scientific Interest, pronounced ‘triple ess eye’) designation, which will guide you towards specific methods for conserving existing biodiversity. If you have a degraded grassland habitat which isn’t designated and has the potential of being restored to a specialist grassland, it may fall into one of these categories:

Waxcap Grassland

Some Neutral and Acid Grasslands with short-cropped turf support highly abundant populations of waxcaps. These colourful mushrooms spread through the soil with hyphae, and thrive in nutrient-poor conditions, on moss-rich grassland. This habitat can be degraded through ploughing, muck spreading, fertilising and spraying of pesticide. They are most often found in upland habitats which are intensively grazed by sheep and/or horses.

Coastal Grazing Marsh

This is typically land reclaimed from salt marsh, which may still be flooded in winter with freshwater. It is often a valuable breeding habitat for wading birds, and provides lush, rich grazing due to the alluvial soils. While traditional conservationists have maintained a short sward for breeding birds through intensive grazing and mowing, research has found that ground-nesting waders are more likely to be successful where there are patches of longer grass and scrub scattered across the habitat. These are thought to create more abundant sources of alternative food – small rodents – which distract predators from the eggs.

As a transitional habitat with high productivity, coastal grazing marsh may rapidly succeed to scrub and then wet woodland if left ungrazed. However, if regular flooding is severe enough, this alone may prevent scrub from colonising lower sections of the habitat. Flooding also attracts large flocks of wildfowl, which eat invertebrates in the grass and soil. Drainage can severely reduce the biodiversity of this habitat by preventing winter flooding.

Calaminarian Grassland

On toxic soils, with high levels of heavy metal contamination due to natural sources or (more likely) mining, a nutrient poor grassland habitat forms. This habitat hosts a unique community of specialist plants which are adapted to the toxins. The grassland may persist for many decades, but eventually it will succeed to scrub and woodland. 

This process of succession can protect the toxins in the soils from leaching into nearby watercourses by sealing them in with a layer of nutrient-rich leaf litter. However, some organisations prefer to maintain the specialist Calaminarian Grassland habitat, by stripping off the richer soils above, exposing the toxic substrate below. This can increase the likelihood that toxins flow into local watercourses.

Sand Dunes

Shifting sand dunes are stabilised by Marram Grass, then colonised by grassland, which is often home to rabbits in Britain. This creates a short sward that may be rich in biodiversity, hosting many hundreds of different plant species. 

However, without disturbance, scrub will rapidly encroach (especially Gorse and Sea Buckthorn), so many land managers carry out burning or cutting of scrub on a cyclical basis. An alternative system which maintains a short sward involves grazing with a large herd of Highland Cattle and Ponies at moderate intensity. Sheep are used in some dune systems, as they have a similar grazing effect to rabbits.

Contents