Big areas of land have been underwater for long periods over the past few months, which may affect the productivity of the ground for the year to come. Land drainage can be very expensive, costing from as much as €2,500 to €3,000/acre where very big jobs are carried out on wet farms.

However, substantial land drainage jobs are not always required and, often, by simply cleaning the drains and rivers already on your own land, a massive difference can be made. Numerous drains and rivers across the country are full of silt, or are overgrown with trees and briars that are reducing their effectiveness. By simply cleaning these drains (not deepening), a huge improvement can be achieved.

Taking out a tree growing in the bank of a river is a good place to start (you may need permission from the Department to do this). Cut the tree first if it is safe to do so and remove what remains with a digger. The bank of the drain/river may have to be reshaped when the roots are taken away. By removing a tree, you are reducing the chance of branches falling into a river and clogging up the flow of water. The tree itself causes the banks to close in, reducing the volume of water a river can hold. When farmers open and clean old drains, they often stumble across very old shores that could be over 100 years old. Once the drain is cleaned, these ancient shores start working again just as they did 100 years before. In the 1970s, farmers removed old ditches and drains in their land to increase the field size for larger-scale tractor work. This progressive step resulted in old drains being closed in.

In the majority of cases, these drains were put in for good reason and not on a whim. If you put in a drain with a pick and a shovel it wasn’t for the good of your health. Farmers should reassess areas where drains were removed and consider adding a pipe drain or open drain, if necessary.

Cleaning drains

Jim Leamy, a plant hire contractor from Cashel, Co Tipperary, is a big advocate of the maintenance of drains on farmland.

“A drain that is maintained and cleaned regularly (every five to six years) is very easy to clean and a digger will fly through work because there won’t be a huge amount of material to move, which will help keep the cost low,” explains Jim.

He says the water in a drain that is maintained will move faster which helps to keep it clean and reduces the buildup of debris and weeds. In Tipperary, it has mainly been dairy farmers who have been looking for his services in the last two years.

“The expanding dairy farmers are trying to improve the marginal areas in their farms because these areas will be needed as cow numbers increase,” according to Jim.

“A good digger driver will find it very easy to clean a drain or a river. When, they put the bucket in they shouldn’t find it hard to know the base of the river because it will be firm. If they go any lower, they will find that they are digging rather than cleaning and this is not required in the majority of cases,” says Jim.

The need to transport material a distance away depends on the state of the watercourse being cleaned. “If there is a lot of silt and weeds, a dumper will be used to take it away for spreading on the land again, but if there is only a small amount it will be placed at the side of the bank where it will disintegrate,” said Jim.

In a day, Jim says he would clean 300 to 400 metres of a well-maintained drain and this would cost €45 to €50/hour.

If there was a lot of material to be moved, it costs another €35 to €40/hour for a tractor and dumper but every site is different.

Sometimes Jim comes across deep, open drains that have banks fallen in certain places. He says the pressure of water has caused the collapse and the best way to solve this is to put a stone drain in to meet the source of the water pressure. This will let the water away quickly without causing the bank to collapse.

Over the past number of years, wet spots and ponds have developed on both tillage and livestock land that were never there before and they are very slow to disappear. These wet spots have developed for a number of reasons, including large volumes of water falling over a prolonged period degrading the natural structure of the soil, land tightening due to machinery and livestock traffic in damp weather and poor soil health.

Jim says that, in the past, wet spots were tackled with sub-soilers in an effort to break the pan, but this method did not work in the long run. Now, when he comes across a large wet spot in a field, he puts in a drain with 80mm perforated plastic pipe and 2in round drainage stone and goes to the nearest watercourse.

“You need to get the water away from the spot first and, when it is dry enough, you can then start trying to improve the area fertility wise to avoid the problem happening again,” says Jim. Having good soil structure in the first place is one of the best ways to have land in good shape to cope with prolonged wet weather. A healthy soil regenerates its structure, enables water percolation and storage and supports plant and biological life.

Soil crumbs are made up of sand, silt and clay that are held together by organic matter. A soil with lots of these crumbs has good pore space, which allows water to percolate and also enables soil to breathe. However, if these crumbs degrade, the clay and silt will break down and wash into the pores clogging up the natural drainage.

The best way that farmers can ensure the natural drainage of their soils is working well is to improve the overall fertility and feed the soil with organic matter.

Earthworms play a critical role in maintaining healthy soils by consuming the fine soil that is moved down into the soil profile and taking it back to the surface where it is mixed with organic matter to help form humus.

Earthworms will be most active where there is food. By feeding the earthworms you are helping your soil’s drainage and its ability to cope with difficult weather.

This practice will help to avoid wet spots and ponds in your field forming in the future.