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Waterlogging

a lawn that is heavily waterlogged creating large puddles
a heavily waterlogged lawn which has created puddles

Into every life some rain must fall – just don’t let it water-log my lawn…

To quote the stereotype it’s true that the English love to talk about the weather as much as we like tea, crumpets and the Antiques Roadshow. However, although we know it’s guaranteed to rain, it is impossible to know how much we are going to get – just ask the Met Office (are you sure there’s no hurricane coming Michael?…).

At Lawntech we treat thousands of lawns and see many different problems due to excess water. When we get too much rain there comes a point where the soil struggles to absorb any more water and it gets saturated to the point where it becomes waterlogged. Stepping onto a waterlogged lawn you will notice the soil feels `squelchy’ underfoot and in some cases, puddles may form on the lawn. In extreme cases, the lawn becomes flooded and submerged, whilst prolonged waterlogging can cause lawns to suffer and in extreme cases, it can die.

What Causes Waterlogging?

This really is as straightforward as it sounds. The soil becomes waterlogged when water builds up and is unable to drain away, which in turn creates various issues for the grass. A sudden downpour rarely harms the grass plants which make up your lawn, it is prolonged periods of saturated soils that cause the most damage.

Waterlogging brings a number of problems, one being the presence of the water itself which limits the crucial oxygen supply to the grassroots. It also prevents carbon dioxide from diffusing. The roots’ functionality is reduced or even stopped completely as they start to die, which in turn enables the invasion of rot and decay organisms. In addition, essential nutrients are leached out which results in hungry soil as well as severe compaction. The lawn can also thin out, creating an environment where moss will pitch-in to the new gaps and thrive in the damp conditions.

In most cases saturated lawns naturally recover as conditions start to dry out but it could be that repairs are needed to reinstate a severely waterlogged lawn once the water has receded to create an environment where new grass seed can thrive. This will likely involve aeration, top dressing, seeding moss control and fertiliser application. We recommend that lawns prone to regular water-logging should be assessed to see if it is possible to fit land drainage which will relieve the problem.

How to Deal With a Waterlogged Lawn?

Let’s begin with the short-term solutions; If the waterlogging was caused by a flood, then wash down hard surfaces and collect up debris to avoid drains being blocked and allow a steady flow of water to remove pollutants. Try not to step on the soil, as doing so will compact it and worsen the conditions. Remove any damaged shoots from affected grass plants. If the waterlogging has occurred in the spring, then apply a balanced fertiliser to improve growth.

Now for Long term solutions. If your waterlogging is serious, and with prevention being better than cure, we would suggest trying to improve the soil structure and drainage.  The most popular of these solutions are Land Drains and French Drains. Both of these consists of a trench (or series of trenches), dug into the lawn and lined with a porous membrane. The trench is then filled with shingle and/or graded stone before being finished off with topsoil so that the relaid turf on the surface returns to being level with the rest of the lawn. The difference between a Land Drain and a French Drain is that the former also has a pipe (often perforated) embedded along its length to carry the excess water away more quickly and efficiently. In both of these cases, the trenches are dug at a shallow angle so the water flows along the trench by gravity to a strategically-placed Soakaway. From there it is guided to dissipate harmlessly underground. The porous membrane is designed to filter out silt from any water which is washed into the trench. Without this filtration, drains of either type can easily be clogged with silt and inundated with the very water which they exist to channel away.

Air Blast Aeration

If the soil underneath a waterlogged area has been badly compacted over time, your lawn may be a good candidate for Air Blast Aeration. Unlike traditional aeration, which typically involves inserting a set of spikes or tines into the soil to a depth of 3” (7.62cm) to leave thousands of bore holes behind, Air Blast Aeration uses a single spike (or pair of spikes) to drive right down to 1 metre below the surface. Once there, a shot of compressed air is blasted at high pressure, in up to 4 directions at a time. This breaks up the compacted sub-soil, helping to drain away any water which is already present and creating new channels for rainwater to drain away. The machine is used in a pattern which enables the ground which has been broken up below ground to make a new labyrinth of inter-connected pathways which not only allow the free passage of rainwater, but also essential oxygen and nutrients to help reinvigorate the lawn as a whole. Some operators will also add dried seaweed on the final blast, to help keep the new probe holes open and enable continued free drainage of rainwater. Others top up the holes with fine gravel to keep the pathways from filling up with soil. Air Blast Aeration is seen as an excellent long-term solution to waterlogging, to the point where operators are prepared to offer a 10 year guarantee on the effectiveness of their treatments. For more information, click on this link;   

http://www.airblastaeration.co.uk/

If your lawn does not warrant such extreme measures but you plan to grow your own plants in areas which are prone to waterlogging, you might consider doing so in raised beds. This will raise the growing plants’ roots higher up and clear of the inundated soil.

Hopefully, these suggestions will help your lawn to combat even the worst effects of waterlogging. Your lawn’s condition should improve as a result, but it’s equally important to stay vigilant and not let it go the other way and become too dry

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