Thatch is best described as the dead and decaying plant material found within the upper surface of a green's profile. It is the contributory factor for good or bad playing performance of a bowling green.
If allowed to develop to an excessive amount, it will cause slow and heavy playability, especially when the green is wet. You will see and feel the bowl sink into the surface taking a massive amount of momentum out of each shot played. Tracks in the surface can also be produced after repeated use.
Firmness is everything! Also, secondary management problems, such as disease outbreaks, dry patches and the promotion of annual meadow-grass, will also be more common.
It is the intention of this article to offer something new and exciting to the industry for bowling green thatch management: analysis and implementation.
Thatch - inputs versus outputs
The production of thatch is the result of accumulating dead and decaying material from roots, stolons and rhizomes, dead leaves etc. However, this accumulating material will, hopefully, be removed at the same speed as it is produced so that excess amounts are not created.
The speed at which it is produced depends on many variables probably unique to each and every green; drainage quality, soil type, grass species, climate, maintenance programme, etc. The speed at which it breaks down and/or is removed also depends upon these same factors, but more so related to the appropriateness of the maintenance programme. Balance inputs with outputs and quality is usually secured.
How do you know if you have too much thatch? What is the right amount to have in the first place? How long will it take to remove, and what methods do you need to use to do it? You must first answer these questions if meaningful objectives are to be set and achieved within any improvement programme.
: the current way the industry measures thatch (by visual depth in mm) is not really accurate enough to fully understand it and mitigate its risks.
Fact: if we are to successfully rule out thatch as a performance problem we must understand its impact by first accurately measuring it.
STRI has developed a low cost testing service to help bowls clubs understand their situation regarding thatch management. Before now, a rather rough and ready method of measuring its depth was used, which is nowhere near as accurate or meaningful as laboratory testing for the exact amount. You need to fully understand where you are now, before you can hope to understand where you need to be (and how to get there!).
Core samples from within the green's upper profile (100mm, 4 inches) are taken by hand on site, sent in to our laboratory, before being divided up into depth sections. Each section cut is weighed, put through a burning process, and re-weighed, producing the result of exact thatch/organic matter material content by % weight not visual depth. It is both highly accurate/objective and quick to complete. An STRI agronomist, who assigns an optimum target value to work to, then gives the results feedback to the club. Once this target is known, STRI can supply the key information needed to successfully get from point A to point B to reduce thatch amount and meet the target set.
This feedback will include the type of machinery, frequency of practice, and expected timeframe. Conditions will then improve as the programme is fully implemented: producing a firmer, faster playing surface over time.
Targeting the correct areas
The testing service will tell you both the amount in need of removal and, critically, where it lies within the green's profile. If the material is close to the surface (within one and a half inches, 35mm or so), deep scarification and hollow coring combined will be the best options to choose, with emphasis on scarification.
Scarification has a limited working depth but can, if used correctly, remove much larger amounts of thatch than hollow coring alone (especially with some of the more modern pieces of scarification equipment). If the material lies deeper than one and a half inches, or 35mm, hollow coring will play a bigger part, used in conjunction with scarification.
If we didn't know where the target was, we may choose the wrong options and delay the development process or not move forward at all.
Getting on top of the situation
It is essential to the current and future performance of the green that a curative programme be implemented to solve the problem, if highlighted.
Fact: Increasing preventative maintenance only, such as solid tine aeration, topdressing rate/quantity, and/or verticutting etc., will often not make sufficient headway where thatch amounts are excessive.
They are, however, all-important preventative measures but, if an excess exists, better to tackle it using curative methods and reap the benefits quickly.
This could mean contractor assistance owing to the specialised machinery needed to de-thatch effectively. It should, thankfully, come as much comfort that a lot can be achieved in a short space of time; provided the correct de-thatching methods are used.
Too much thatch in your green is nothing for you to be embarrassed about. Recent climatic changes, the natural growth of grass and, perhaps in some instances, inappropriate past management, may have collectively led to the current situation where thatch amounts are too great. It is more important that the main threat to achieving firm, fast playing quality - excessive thatch - is recognised, curative measures implemented and the problem overcome, than to continue on the same path with ongoing problems.
Two major innovations have occurred that will make the difference here: STRI's thatch/organic matter testing service, and improved de-thatching equipment. The testing service should be used as the starting point to find out what actions are needed at your club regarding thatch, so that you can successfully overcome them and enjoy better playing quality.
Fact: In the author's experience, excessive thatch is the most common cause of poor performance-related problems for both surface playability and maintenance management, together with its associated costs.
Let's work together to get on top of it!