The main event at Defender Burghley Horse Trials

Defender Burghley Horse Trials is a firm fixture in the calendar for many horse lovers, attracting more than 173,000 visitors over the four days to witness the world's top event riders compete.

Many spectators would, however, be surprised to know that the competition surfaces are professionally managed year-round.

The first event was held at Burghley, near Stamford in Lincolnshire, in 1961 after a leading competition at Harewood in Yorkshire was cancelled due to a suspected outbreak of Foot and Mouth disease. It has since hosted two World Championships, six European Championships and one Young Riders European Championship. The parkland venue is also in the running for the 2026 FEI World Championship, despite a move to synthetic arena surfaces for the dressage and showjumping elsewhere.

Scene of the climactic show jumping phase that has cemented the career of many an eventing legend and the initial dressage phase, the main arena has remained in the same spot since 1961, but the cross-country course has taken many different routes, explains clerk of the course Philip Herbert.

"The cross-country track is 6000-7000m long or longer, depending on the nature of the competition - whether it is a championship or young rider event. The most significant development is that we now maintain the track year-round rather than relying on livestock grazing the parkland."

Until about 2000, all the obstacles were built on site and had to be dismantled to alter the course. With the advent of rough terrain forklifts, many fences are now built in the workshop and then anchored onto the course, meaning they can be moved for ground maintenance.

Often, they are redesigned or reversed so that the track can run in the opposite direction.

In the 1980s, eventing's international body, the FEI, its national affiliates and rider groups pressed for better management of ground at competitions and for Burghley, which takes place in early September, this is especially demanding.

"It can be any weather: very wet or very dry. Our first action was to remove the livestock from the course - they can damage the obstacles and cause poaching or tracks. Fencing the course also protects it from vehicles driving over or the hunt riding over it."

To tackle dry conditions, an irrigation programme was put in place - initially with equipment borrowed from a local potato grower!

"We started by fencing the course off in early July and then adding the crowd fence just before the event; now the majority is protected with 'permanent' electric fence, which is however easy to move if we re-route the track."

A programme of weekly mowing from March to October was instigated, and the mower of choice is a seven-deck Toro Groundsmaster 4700D. Mowing height is key, explains Guy Herbert, responsible for much of the groundcare work at Burghley.

"We aim for a cut height of 3in on cross-country days but work down at 2.5in for much of the year, going to 2in in spring and early summer when we're putting on water and fertiliser. Heading towards the event, cut height is raised by ¼in each week, which I find helps avoid thatch building up in the top."

Fertiliser and water applied to ensure the perfect green sward for the world's TV cameras means plenty of growth in the final few days before the event.

"George Burnham, who drives the mower, used to do a final cut on the Friday before Saturday's cross-country," says Philip, "But the site is so busy now, it's hard to get round, so the mower has LED lights fitted and he cuts through the night."

A handy addition to the mower, a star strimmer, is swapped for one of the decks to cut around the fence posts, but is now due for replacement. The yearly maintenance programme begins on the Sunday after the event, Guy confirms.

"If it's been a dry year and there is minimal damage, a pass with an Aera-vator will take out hoof marks. I try to avoid manual divoting as the soil mix can encourage weeds, but in a wet year we do need to add some material."

In the dressage arena, the centre line and perimeter may need subsoiling to take out compacted tracks. Mowing three or four times in the autumn helps revitalise the sward, and Guy adds:

"If there's been a lot of damage, I'll use a Twose slitter which has multiple 200mm long blades, with a Joskin harrow towed behind it. This takes out poaching and the harrow tines encourage regrowth."

The slitter comes out once again at the end of autumn to let any frost get into the ground; slow release fertiliser is also applied.

"We'd build any new ditches or steps at this time too, and reprofile ground where needed," comments Philip.

Leaf mould and waste rubber or fibre from synthetic riding surfaces are also deployed where needed, spread and integrated with the soil to add stability at the same time as 'give'.

Repairing take-off and landing points has become more significant in recent years, Guy comments, due to the increased use of 'skinny' fences to test rider accuracy. "Each horse uses the same piece of ground, so it has to be firm and stable."

At the end of winter, slitting takes place as early as possible with the harrow taking out dead material.

"We'll spot spray weeds to keep the sward clean; in 2022 when grass was dying off, the weeds persisted. We also tackle clover which has deep roots and withstands drought but is slippery underfoot, so has to be removed."

In the main arena, creeping bent is an issue, so is scarified off with a Wiedenmann flail collector in late summer.

"The surface looks sparse afterwards, but soon comes back," comments Philip. Summer fertiliser with iron is applied to green up ahead of the event, and in a dry year, a programme of Aera-vating and irrigation is used.

"We Aera-vate first to loosen the surface and make the most of the water," explains Guy. "There's a modern irrigation system with three Briggs reels fed by an electric pump extracting from the lake via 4500m of underground pipe.

At full capacity, the system can put a cubic metre of water on the cross-country course every 45sec."

It's a delicate balance, however, since the ideal ground for eventing is what a racecourse groundsman would call 'good to firm'. A moisture meter is deployed and the team works with consultant Mark Lucey to measure ground firmness using a drop test in the final weeks before the event. Of equal importance, Philip walks the track - all 7000m of it - regularly.

"Most of all it has to be consistent over that 7000m, where there are four different soil types, from clay around the lake to limestone, and varying soil depths," he comments.

All clay areas have land drains and the subsoiler is deployed, if necessary - in this case, a Howard Paraplow with angled legs that lift rather than opening up the surface. A notched Guttler press follows to firm and even the surface without compacting.

As Burghley becomes a hive of activity in the final week before the event - most marquees and other infrastructure start coming in a month ahead - there is little left for Philip, Guy and the team to do. Fence judges (who record any competitor faults at each obstacle) are briefed and fences dressed with flowers, greenery or, in the case of Daniel Lambert's Sofa, a two-thirds life size figure of England's heaviest man himself.

"We're always pleased if there is a shower of rain in the final week before the event; we might irrigate at night in extreme heat but not at the detriment of consistency. With the good thick sward, the footing doesn't change much," Philip comments.

Climate change has offered groundsmen some extra dilemmas in recent years, and in hot years such as 2018 and 2022 the shortage of water meant having to irrigate to green up and soften up at the same time. "This wet summer has actually been useful," he says. "Everything has remained green and growing."

Water crossings are required to be no more than 150-200mm deep for safe negotiation at speed. At Burghley, natural features the Trout Hatchery and Lake are used, but the soft material below the surface is dug out and replaced with hardcore topped with 100mm of 20mm limestone, which is firm with a small amount of give. To include an island on the lake, 'aqua dams' (waterfilled barriers) are installed to control the water level.

Philip's team work closely with the estate staff who maintain the public areas at the event and include a head forester, responsible for the wonderful trees that add to the visual appeal of the course.

It's a huge team effort all round to produce arguably the ultimate test of the equine athlete on natural turf, a surface that horses have been bred to perform on for centuries.

A renovation revolution

Requirement for higher standards of turf presentation has filtered down through the levels of eventing and to other related sports and it is common for equestrian fixtures to use an 'aera-vator' of some sort to address firm ground conditions.

"The previous approach was to apply sand, especially to fence take-off and landing points. Prior to installing irrigation at Burghley, we put silt along the course in three dry years," Philip recalls. A visit to Saltex brought the Aera-vator to his attention.

"I couldn't understand why one piece of turf was softer than the ground around it, but it had been treated with the Aera-vator. This, and its bigger brother the Agri-vator, use an oscillating, vibrating tine system to loosen the soil to relieve compaction and allow air and water to infiltrate. British Eventing built up a fleet of 18 machines which are loaned out to events across the country, and Philip comments that they have been key to the progression of the sport."

"But they can be a bit slow if you are looking to treat a large area. So I commissioned the 'Equi-vator' which is a 5.2m folding version, built out of Aera-vator components."

Parts are costly, he comments, at £1600 for a new set of tines, but Reesink UK now have the franchise and offer a ready supply of spares.