Managing pasture for horses

UK - January 31, 2011

What type of pasture do horses need?
Most horses can derive all their dietary needs from grazed grass and hay. But the type of grass they need is very different to that of cattle and sheep - ideally fibrous material with moderate digestible energy and low protein.

The high sugar and protein content of modern agricultural swards, particularly those that have been heavily fertilised, can be dangerous for horses – leading to potentially life-threatening health problems such as obesity, laminitis and colic.

Horses also appreciate a wide selection of different grasses such as creeping red fescue and timothy, and herbs such as yarrow and sainfoin, something perennial ryegrass monocultures cannot offer.

Horses have small stomachs and spend most of their time grazing to achieve a constant supply. They use their nose and lips to search out desirable plants, and use their long front teeth to grasp and cut vegetation off to within 1cm of the ground.

Does horse pasture need fertiliser?
Nitrogen fertiliser should not be applied to pasture where horses are grazing as it produces feed too rich in nutrients. However, swards shut up for hay may benefit from extra nitrogen to maximise production. Clover, often incorporated into agricultural seeds mixtures because of its ability to add nitrogen to the soil, is not good for horses.

What should be done with droppings?
Unlike cattle and sheep, horses create latrine areas where they return to urinate and defecate, but will not graze. This may be natural worm control – as these toilet areas contain 500 times the number of infective worm larvae compared to the grazed areas.

Horse latrines are characterised by tall, coarse grass and weeds that have been stimulated by the over-supply of nutrients, and a lack of grazing. These areas are referred to as ‘roughs’, as opposed to the closely cropped areas called ‘lawns.’

Latrine areas must be managed to stop them spreading. Harrowing will distribute the dung and reduce the worm burden by breaking up and drying out the manure, killing the worms. It is essential to rest a paddock after harrowing and to follow a sound veterinary worming regime.

Droppings can be removed manually or with a motorised muck collector. This stops the spread of latrines but removes potentially useful nutrients that the grass could benefit from in future. It also may increase the risk of worm infection as horses may unknowingly graze areas where dropping once lay.

Picking up some, but not all droppings offers an acceptable compromise. By removing those at the edge of a latrine, horses will keep using the same area but will not extend the boundary.

Controlling weeds in horse pasture
Weeds such as ragwort, thistles, docks and nettles, are opportunistic invaders which will take every chance to establish in disturbed ground and bare patches of soil.

Weeds need controlling for many reasons. Some such as ragwort are poisonous to horses; others will take over the paddock if left unchecked leaving no space for grazing, while others can spread to neighbouring properties which won’t help neighbour relations. Weeds also make pastures look messy and untidy.

The Weeds Act 1959 requires that if an order is served on them, landowners have to control common ragwort, broadleaved and curled docks and spear and creeping thistles – all commonly seen on badly managed horse pasture. 

The Ragwort Control Act (2003) strengthens this by placing the onus on the occupier to take action where ragwort is posing a serious risk to grazing animals.
 
Prevention is better than cure – so keeping out-wintered horses on a sacrifice paddock rather than poaching the whole grazing area, will restrict where weeds can invade the following spring.

Where weeds have taken hold, there are ways to get rid of them – including digging them out, cutting them down and using herbicides – either as a targeted spot treatment using a knapsack sprayer, or as a broad-acre application using a weed wiper or a boom sprayer on the back of an ATV or tractor. Before blanket spraying check whether the pasture is species-rich and call in an expert to identify the plants if unsure.

A range of herbicides is available, from those that kill everything, including the plants that horses like to eat, as well as any other desirable species, to those that are more selective in action – not harming the grasses but killing the undesirable broad-leaved weeds.

If herbicides are to be used, horse-owners, particularly those renting pasture, should seek professional advice and assistance. People born before 1964, or who hold a PA1 and/or PA6 certificate of competence in the safe use of pesticides (issued by the National Proficiency Test Council) can use professional use products. For others it is advisable to seek training (visit www.nptc.org.uk for details of your nearest course), or employ a contractor or local farmer.
Whoever applies the spray should always read the product label and follow manufacturer’s recommendations for safe handling and application – including the timing of spraying, how much to put on, how much water to mix with the chemical,  and how long animals should be kept out of the field after spraying.
When selecting herbicides – choose translocated products that have been specifically developed to control weeds in grassland, as these deliver effective, long-lasting control, and negate the need for regular spraying year on year. 

Ragwort
Ragwort is an accumulative poison which affects the horse liver over time and can be fatal. Unpalatable while it is growing, the danger comes when the plant is wilting when it becomes more attractive to eat. It is a particular danger in hay.
Wet springs and summers stimulate its growth and it flowers between June and October. Seeds successfully establish in gaps left by poaching. It can also regenerate from root fragments. Therefore ‘pulling’ to get rid of it is not advisable and manual removal requires digging out the whole plant, most easily done when the soil is damp. Wear gloves to do this.

Cutting only encourages ragwort to grow more – and wilted cuttings must be removed as they pose a high risk. Ragwort can be sprayed with a selective herbicide containing clopyralid as a spot treatment or with a weed wiper which applies the chemical purely to the upstanding ragwort plants. This is best done in late April or May. Horses must be kept out until the ragwort has fully wilted and been removed.

Thistles
Thistles often appear in horse pasture. Creeping thistle spreads vegetatively and any fragmentation of the roots or cutting of the stems encourages even more aggressive growth, from buds carried below ground. Thistles thrive on high levels of potassium, and are therefore often found in horse latrines.

Creeping thistle can only be controlled manually by continual cutting through the season. Spraying with a targeted clopyralid herbicide like Thistlex will do a better/quicker job.

Spear thistles have sharp spiny leaves and unlike creeping thistle only spread by seed which drops within a metre or two of the mother plant. It is therefore vital to stop it seeding, either by cutting or spraying with a selective herbicide before it flowers in July.

Docks
Docks grow in soils rich in nitrogen and phosphorous and flower from June onwards, producing a large number of long-lived seeds which spread on the wind, in hay and manure and by animals that eat them. They can exist in the soil’s seed bank for up to 80 years.  Poaching and ground disturbance encourage their establishment and they can stand a large amount of trampling.

Cutting does not control docks as the parent plant simply sends up a new stem. Digging is more effective, although the roots can reach to many metres deep. The best way to get rid of docks is to use a translocated herbicide that will reach down into the roots and kill them, for example Doxstar which contains fluroxypyr.

Post spraying – important points

• Take horses out of the field while it is being sprayed and do not put back until the withdrawal period is over. This will be indicated on the product label. Some weeds like Ragwort can become more palatable as they die back – be aware of this when re-introducing your animals. 
• Re-seed the bare patches of soil left where the weeds have been removed immediately, so that new weed seeds don’t take the opportunity to re-establish
• Where fields have been sprayed with herbicide – it is best practice to collect any future droppings, compost them and re-apply when well rotted to grazing ground. Do not apply to areas where hay is to be made, or sold/given away to gardeners or allotment holders.

Grazing management
Good grassland management will prevent over- and under-grazing. It can be a difficult balancing act – especially as grass grows as different rates throughout the season. The ideal ‘stocking rate’ is 1-2ha per horse – to produce hay for winter as well as summer grazing.

Where under-grazing is a problem – shut an area up for hay or winter grazing and concentrate the grazing in one area. If this is not possible, excess growth should be cut regularly to stop the grass getting too long and rank and therefore unpalatable.

Over-grazing is more often the problem as horses tend to graze the same areas very short and fields can become ‘horse-sick.’ Rotating horses around a paddock, using electric fence to divide it into smaller sections, will help prevent this – and gives each area chance to recover.

Horses should be moved on to the next section when the height of the shortest grass in the lawns is about 2.5cm, and come back to it when it has grown back to between 8 and 12cm.

Further reading: Managing grass for horses – the responsible owner’s guide by Elizabeth O’Beirne-Ranelagh.