Land drainage: Farmer's creation extends grazing season

Ireland, like the UK, is blessed with some of the best climatic conditions for growing grass in Europe, and that, as we all know, can also be a curse. The ample rain we enjoy favours excellent grass growth on good ground, but it also reduces some areas to bogland upon which only reeds and rushes thrive and into which cows and tractors sink.

A novel approach

Drainage is the obvious answer to this problem, but just how to go about doing so is a question that has puzzled and frustrated farmers in many areas over over the centuries.

Sean Dillon limerick — Sean Dillon on land which was until recently, no better than bog

It is often the case that standard drainage methods don’t work, or fail shortly after installation – unstable soil being one major problem, as is the accumulation of silt within perforated pipes. Due to these difficulties, much ground has been left to nature with bog-type vegetation dominating land which might otherwise be productive, and the problem areas are not just confined to the mountains.

Limerick woes

One local region in the Republic of Ireland which suffers from poor drainage is that which roughly lies between Limerick city and Tipperary town.

Limerick drainage drains — Closely spaced drains may well be the answer for Limerick soils

Here, the much rush-infested land has defeated all attempts at drainage, the soil strata being made up of alternative layers of clay and running sands which can easily shift to disrupt any tile or pipe drainage works. Even subsoiling may only last a few months before the channels are filled again and water is left to accumulate on the surface, and therein lies a clue to a possible answer.

Big diggers, big costs

Removing the surface water, be it flooding the ground or saturating the top 50cm or so, is usually attempted by getting it to flow away vertically, down towards deeply buried pipes

Peebles drainage limerick — A 15cm-wide slot filled with pebbles and spaced at 5m is the answer to saturated ground, according to James Coen

Another approach is to dig larger drains by an excavator and ‘V’ bucket, and then backfill with stone. These tend to be slow and expensive to construct, and run the risk of having the side collapse before the operator has time to place the stone. The idea behind the Scorpion, is to create smaller and shallower trenches, more closely set together, which are immediately backfilled with stone in one single pass.

Soil pressure

The secret, explains farmer James Coen, is to remove the soil from the trench altogether and spread it over the adjacent surface. This eliminates the problem of lateral soil pressure acting to block or distort the passages as it tries to return to position, having been been displaced sideways by a mole or even trenching machine.

Scorpion limerick Coowen — Knocking the soil to the right as it comes to the surface is a key element of the drainage method

It is a question of soil removal rather than displacement, and the affect is to create a strip of ground that is highly porous, rather than rely on an artificial structure formed by pushing soil aside to allow water to run through. The water is then free to drain from the surface and due to the close spacing of the channels it quickly clears the field.

Own design

James, who had been running a drainage contracting business in Co. Galway on the west coast of Ireland, was very much taken by the theory, but could not find a machine to do the job – so he built his own.

Drainage Scorpion James Galway — Here the drum can be clearly seen as the blade enters the soil at the start of a run

The result is a sturdy tool which does just what he wants it to do. This no quick tacking together of a few lengths of angle iron, but a fully thought-through implement that took a good deal of time and effort to perfect. Called the Scorpion after the the design of the tail, it is the result of two years of trial and error with much of the fabrication being done in a professional engineering workshop.

Scorpion tail

The business end comprises of a blade faced with hardened steel which creates a trench around 40cm deep and 15cm wide. As the soil is lifted out of the ground, flails, attached to a spinning drum, knock it sideways to the right-hand side.

Stone scorpion hopper — The farmer provides the stone and a method of loading the six tonne hopper

Two discs run in front of the blade; set 6in apart, they cut the turf to allow a neat trench to be formed without tearing at the sward. Immediately after the share has done its job stone is let into the ground from the trailer hopper to form a narrow stone-filled trench which does not collapse in on itself.

Pebbles rather than chips

The stone used is preferably pebbles of between 25-50mm; crushed limestone is avoided as the associated dust and grit tends to clog up the pores.

Stone cost drainage — The rate at which the stone enters the slit is regulated by a door on the chute

James, who now runs the business with his son Seamus, charges 80c/metre for the service, the farmer supplying both the stone and a loader for filling the topper. Presently, it is the cost of the stone that is making farmers think twice about doing the work, but James believes that he is still one third the price of a digger and uses a lot less stone.

A harrowing finish

The result looks a little untidy to begin with but one or two passes with a grass harrow normally smartens it up and the grass is left to grow through the spoil and soon covers the trench itself, causing minimal loss of growth or crop.

Harrow New Holland drainage contractor — A pass with a grass harrow tidies the surface and allows the grass to resume its growth

A further trick it has up its sleeve is that the axle is powered, helping to prevent it from becoming bogged down, and maintains a consistent speed of around 4km/h. Powering it is a 155hp New Holland T6080 which drives two hydraulic motors mounted on the trailer: One for the drive axle and the other for the other hydraulic motors and rams on the machine.

Extended grazing season

At least two farmers in the Limerick area have tried the Scorpion and are now enthusiastic converts.

Sean Dillon of Pallas Green is one, and he notes that the difference made by the machine is quite incredible. Rush-filled fields which showed around 10% grass are now perfectly grazable over an extended season. The problem he has with his ground is the mix of alluvial deposits which can exceed 80ft in depth before hitting bedrock, and none of these clays and sands are stable.

Last season he treated 17ac and is back for more this year, having been greatly impressed by the results achieved so far. Besides reclaiming land it is the attraction of gaining better results from his fertilser that stokes his enthusiasm.

Earlier grazing

A second farmer who has decided to use the Scorpion again is award-winning Gearoid Maher who has managed to squeeze two more grazings from the land he had drained last year.

Scorpion drainage Gearoid Maher — Gearoid Maher hasn’t touched the mole plough since using the Scorpion.

As a great advocate of soil nutrient management, he is also of the view that the drier ground will make better use of his inputs and increase both grazing and silage quality. He also notes that he was able to turn cattle on to the ground two months earlier than normal and appreciates the lack of damage to the soil caused by the Scorpion when compared to other methods.

MACHINERY