Why good drainage in winter can make the difference by spring

Alistair Dunsmuir
By Alistair Dunsmuir February 25, 2012 12:48

Why good drainage in winter can make the difference by spring

Good drainage is a fundamental requirement of any sports’ turf playing surface, but particularly where the sport is played through the winter months. Where golf used to be predominantly a summer sport, in recent decades the demand for winter golf has increased, encouraged by innovations in waterproof clothing. The increasing pressure from golfers to keep the main greens open, coupled with the economic desire of clubs to maximise their winter revenue, means play is often being allowed to continue where instead it should be halted. Un-drained, soil-based greens do not usually drain quick enough to allow play to continue unrestricted. The result of this is a decline in the quality of greens and a slow spring recovery which, in recent years, has been further exacerbated by cold and dry spring weather.

Why is good drainage so important?

Good drainage should provide firm, underfoot conditions and a strong, wear-tolerant sward dominated by desirable grass species (bent and fescue) capable of coping with sensible levels of play. Poor drainage on the other hand, can lead to a multitude of problems including:

• Influence on sward composition – desirable fine bent / fescue surfaces requires good drainage.

• Thatch levels – poor drainage will lead to a decrease in microbial activity, therefore reducing the speed at which organic matter is broken down.

• Increased susceptibility of the sward to damaging turfgrass diseases.

• Increased surface softness as a result of saturated soil and increased thatch levels leaves the surface vulnerable to footprinting and damage by machinery, which reduces surface smoothness, trueness and pace.

• The level of maintenance able to be completed is reduced, as taking heavy machinery onto soft greens will result in damage to the surface.

• Algae, moss and weed populations may increase.

What are the options for improving drainage?

Where drainage is problematic on golf greens, consideration should be given to improving the maintenance programme. Particular focus should be given to reducing compaction within the soil profile by optimising the frequency and timings of aeration operations, as well as the type of aeration being carried out. Ongoing aeration at constant depth may lead to the formation of a ‘pan’ at the base of the penetration depth, therefore impeding water infiltration, as well as causing other problems such as restricted rooting. Aeration depth must be varied as much as possible and should include the occasional really deep aeration with a verti-drain-type machine or, where the problem lies deeper in the profile, using one of the air-injection machines.

Optimising aeration operations should also help to promote the natural breakdown of organic matter in the profile, therefore reducing thatch levels and enhancing infiltration rates. Ideally it should be dovetailed with top-dressing where possible to maintain the integrity of the tines’ holes, dilute organic matter at the turf base and ameliorate the upper profile. Furthermore, the growing environment around affected greens should also be improved. In particular, the aim should be to reduce shade and increase sunlight and airflow to help dry out surfaces more quickly, therefore reducing the dependence on infiltration rates. If such measures fall short of solving the problem however, more extensive work will need to be considered. The main options include: reconstructing greens to the USGA orUKguidelines, installing a system of pipe drainage or introducing gravel bands.

Green reconstruction

Complete reconstruction should only really be considered where other methods have failed to provide improvement, or where poor design is contributing significantly to the drainage problem. It is a very disruptive and expensive operation, particularly if completed properly and in line with the recommendations of the USGA greens’ section or theUKguidelines (as produced by STRI). Both such methods are based on a suspended water table construction, with a series of pipe drains being installed beneath a gravel carpet before being overlaid with a blinding sand / grit and covered with an appropriate depth of rootzone. Using the correct depth of materials is vitally important to the performance of the resulting playing surface but so is the quality of the materials used – particularly with regards to particle size, shape and uniformity. If the depth of rootzone is too deep or the particles too coarse, the surface will dry out quickly and be difficult to maintain. Conversely, if this layer is too shallow or the material too fine or of poor uniformity, the surface will tend to hold water.

If good quality materials are used and the correct design installed, this approach will provide good drainage and performance criteria for the long-term, given appropriate maintenance. The initial level of maintenance on completion of the surface is increased, however, so it is important that an appropriate budget is available. Similarly, the existence of a high quality automatic irrigation system is vital for this option to be considered. A further disadvantage relates to maintaining consistency between playing surfaces, as the expense of reconstruction usually means that only some greens are rebuilt. The result is to create a playing surface that performs very differently to other greens at a course, unless funds are available to allow all the greens to be reconstructed in the same way. Even when the work is phased over a number of years, however, inconsistencies will tend to occur as the availability of materials change or personnel (greenkeepers and committee members alike) move on.

Pipe drainage

Pipe drainage should be considered the first step for improving basic drainage where full reconstruction is not necessary or too expensive. Ideally, a complete system should be installed wherever possible with lateral drains at two-to-three metre centres and connecting to a positive outfall. Perforated plastic pipes should be introduced into the base of each trench, ensuring that an adequate depth to invert is achieved to avoid drain lines standing out in dry weather and interfering with routine maintenance operations such as deep decompaction. It is also important to consider the fall along the drain line which needs to be adequate enough to transport water away from the area efficiently. A typical cross-section of a drain trench is illustrated – the perforated plastic pipe is clearly defined in the base of the trench, with the remainder being backfilled with a small, hard aggregate, blinded with a coarse sand / grit and topped off with a good depth of approved, high quality rootzone.

Installing pipe drainage is considered to be a relatively inexpensive way to improve drainage, certainly when compared to reconstructing an entire green. It should also provide a relatively long-term solution, although the actual longevity achieved will very much depend on the quality of the initial installation, as well as the level of ongoing maintenance. Unfortunately, installing pipe drainage is quite disruptive and greens do need to be taken out of play to allow the process to proceed successfully, and allow time for the turf to be re-established along the drain lines. Surface levels may also be affected in the short-term as settlement along drain lines takes place. Usually this is only minor and can be easily overcome with top-dressing, however, as long as the installation process ensures each layer is adequately firmed.

Gravel banding

Gravel banding should only be considered as a secondary system of drains, where at least some underlying pipe drains have already been installed. Narrow bands are introduced into the surface at very close spacings and backfilled with a small hard aggregate or Lytag, with the aim of improving surface drainage by increasing the efficiency with which water can move from the surface to the underlying drains.

Being relatively inexpensive and non-disruptive, this is an option often taken by many clubs and often where no underlying pipe drainage is installed. There are disadvantages to this approach which should be carefully considered prior to embarking on extensive work. Firstly, gravel bands can be relatively short-lived in their effectiveness, although the exact life expectancy will very much depend on the quality of ongoing maintenance. There is also an increased risk of treated surfaces suffering as a result of differential drying during hot dry weather, as well as the aggregate material interfering with hole cutting and certain aeration operations. Although disruption to the playing surface is minimal compared with that caused by installing pipe drainage, there is also a risk of surface levels being adversely affected on completion as a result of heave of the surface during installation.

Conclusion

There is much to consider, therefore, when deciding on the best approach for improving drainage. Often compromises are made due to budget constraints or because of the requirement for immediate gratification with only minimal upset. The options available for improving individual greens are often constrained by site limitations or design, however, and it is for this reason that it is usually best to seek the advice of an independent agronomist or drainage specialist who can provide guidance about the best options as well as the pros and cons of each. One thing is for certain, it usually does not pay to compromise on the work being undertaken by using sub-standard materials. Whilst saving money in the short-term, such compromises usually lead to a wealth of problems, usually drainage related!

Kath Bentley BSc (hons) is a turfgrass agronomist with the STRI

Alistair Dunsmuir
By Alistair Dunsmuir February 25, 2012 12:48
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1 Comment

  1. termofillness (@termofillness) February 25, 13:04

    Get your drainage sorted out NOW http://t.co/ocLZdg6P

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