Greens measurement


“Are the Nations Courses up to Scratch?”  by Alistair Beggs


Alistair Beggs, stri agronomist, official agronomist to the ransa open championship committee,cons

Alistair Beggs

Alistair Beggs, who has recently joined the R&A (and therefore has stood down from FineGolf’s Advisory Panel) used to be an STRI agronomist and an Official Agronomist to The R&A’s Championship Committee (a role that Jim Arthur – the world’s foremost golf agronomist – held for many years).

Alistair has kindly written for the FineGolf  readership a report on the major work the STRI (the UK’s leading agronomist consultancy) has been conducting over recent years.

The STRI have been collecting objective measurement data on some 4,000 greens across 586 British courses (that is up to 2016 and it continues) and Alistair’s report gives the most accurate picture of the state of the nation’s courses as has ever been taken.

An old clubhouse joke frequently asserts that every golfer thinks they know the answer to improving their golf course. True to form, a recent survey even suggested that 74% of golfers blame greenkeepers if a course is below standard.

The reality is that greenkeepers and agronomists are the experts and they need support from golfers to be able to pursue a long-term policy of improvement in line with the conclusions of the STRI report:

“Greens dominated by finer grasses offer superior performance.”

which can be summed up by FineGolf’s own philosophy on the subject:

“In all aspects of smoothness, trueness, high green speed, dryness, firmness, and low thatch content, greens with a higher proportion of fine grasses give better outcomes of putting performance, all the year round, than those dominated by annual meadow grass (Poa annua)”

All discerning golfers should read this report in conjunction with Nick Park’s article on the value of FineGolf and then politely ask the management of their own club what steps they are taking to objectively measure outcomes of greens performance, as a first step on the road to improved putting surfaces!

Alistair says:-

“In recent years there has been a real clamour from many clubs for the development of a system which allows them to measure performance and progress on the golf course. We live in an era where target setting is king and there is little sense in having targets if we can’t measure progress against them. Up until now assessments on golf courses have been largely qualitative or subjective and the problem with this approach is that there are always those who do not believe. Some will agree and some will not. The need for second and third opinions abounds and often clubs fail to make the progress they seek. Measuring eliminates opinion and deals in facts which cannot be disputed.

STRI has been proactive and led the market in the development of a suite of tools which are now being used to quantitatively assess the playing performance of golf greens up and down the country. Over the last four years performance testing has taken place as part of our site visit work and has allowed a large amount of data to be captured on the performance of the nation’s courses. We call this the STRI Programme. Some 4,000 greens have been tested during this period, from those being prepared for golf’s greatest championship, to those courses where most of us play our day-to-day golf. Live data is now being used to influence maintenance programmes on golf courses. The results are fascinating but before these are discussed there is a need to explain the process, what is being measured, and how?

In determining the characteristics that are important to the golfer and the greenkeeper (it is vital to take both into account) we focussed on five main areas:

1. Smoothness and Trueness of Roll

Over the years many golfers have said that the most important characteristic of a golf green is how smooth or true it is. In fact in scientific terms we have identified that smoothness and trueness are two totally different parameters. Smoothness is a measure of vertical deflection or “bobble”, whereas trueness is a measure of lateral deflection or “snake.” Golfers will appreciate that both can impact on the run of a putt and whether or not it goes in the hole. So how do we measure smoothness and trueness? In conjunction with The R&A and Sheffield Hallam University, STRI has developed the STRI Trueness Meter™ which measures both parameters very accurately. The unit is pushed over the surface of a green, with a steel ball underneath, which has the same footprint and down pressure of a golf ball and measures the deflection across vertical and lateral planes. The degree of deflection is measured over a ten metre run, a number of runs are carried out on each test green and averaged together to give a final value. Its use is currently exclusive to the STRI Programme and provides courses with a benchmark of quality and performance across greens and, subsequently, clubs are able to measure annual improvements in their playing surfaces.

The ‘Holing Out Test’  recently developed by The R&A measures reliability of surface (see rather than smoothness or trueness. This is a repeatable and affordable method and when used in conjunction with the STRI Trueness Meter™   it gives a more complete picture of how greens are performing around the year.

trueness meter, truenessmeter

The Trueness Meter on the 10th green at Royal St George’s

2. Green Speed

Whether we like it or not green speed is very important to the golfer and seems to be a key factor in how much or how little a golfer enjoys the playing experience. However, as has been the case in the past, when speed is used as the sole arbiter of quality, outcomes can be very misleading, and the reality is that fast bumpy greens are probably the worst surfaces to putt on! So optimising speed within realistic target ranges (adjusted to take account of course type, resourcing, geography etc) and balancing results with smoothness and trueness is very important. Green speed is measured using a stimpmeter  and normally yields values of between 7ft and 11ft in the UK.

(Editor: It is worth reading the Turf Fox’s article on ‘green speed new facts’ for more detailed information.


The Stimpmeter


3. Moisture Content of Profiles

Moisture levels within soil profiles can have a big impact on how greens perform. Some greens (particularly those with low organic matter levels in surface layers) show relatively low levels of moisture even after substantial rainfall. This is because moisture passes through their profiles reasonably quickly because it is unimpeded by spongy thatch. Interestingly these same greens stay firmer after rain. The other extreme where even relatively small amounts of moisture lead to pronounced softening is very common and is usually associated with thatch problems. Moisture content data is strategic in its value particularly when it is combined with firmness and organic matter data. It can tell us a certain amount on its own but in combination with other data sets it is really powerful. It is measured using a moisture probe.

4. Firmness of Surface

Is a key characteristic if the authentic experience of playing the game along the ground in the UK is to be preserved. As I have already suggested firmness is inextricably linked with moisture and organic matter levels and in combination these characteristics determine how a surface will perform in a variety of situations. Agronomically greens should be firm both to support the grasses and to ensure that surfaces remain playable even in extremes of wet weather (which seem to be becoming all too common). Firmness is measured using a Clegg Impact Hammer which has its origins in civil engineering. A decelerometer is dropped from a fixed height and measures the hardness of a surface in gravities. We can usually expect values between 70 (soft) and 130 (firm).

Clegg Hammer

The Clegg Hammer


5. Organic Matter (thatch content of profiles)

Organic matter is a natural component of all soils and rootzones but it is important that its presence in upper layers is not excessive. If there is too much it can lead to moisture retention and surface softness. Furthermore certain grass types, particularly annual meadow grass (Poa annua), produce a particularly water retentive type of material, rich in cellulose, of which there does not need to be excessive amounts for organic matter to cause problems. In contrast the finer grasses tend to produce a woodier type of organic matter which is nowhere near as water retentive. Therefore greens with a high content of finer grasses can tolerate higher organic matter levels without softness becoming a problem. Organic matter is measured by taking cores of soil from golf greens and burning off organic matter in the laboratory. The result is given as a percentage and can be assessed through varying depths. Accumulations are not always at the immediate surface.

Data have now been collected from golf courses since 2009. In total some 3,775 greens have been assessed on 586 courses across the UK. Data collection has taken place in a variety of weather types and in a variety of situations, with some clubs undertaking major improvement programmes when preparing for major championships and other clubs doing little or nothing to improve surfaces.

It is not possible to present all the data but here are the most interesting indications that have been drawn from the data analysed.  The sample size is large enough to smooth out climatic and maintenance anomalies and give as accurate a picture of the state of the nation’s courses as has ever been taken.

Conclusions :

1. Most of STRI clients who have participated in the STRI Programme have made progress over their period of involvement. Those who have participated the longest have seen the greatest relative improvements in the performance of their greens.

2. Average smoothness and average trueness indicate that UK golf greens are far from where they should be in terms of the quality of roll they offer. Links greens, which tend to have higher proportions of fine grasses (although not exclusively so), tend to perform better than parkland in both categories being on average 20% better.

3. Green speed averaged out at 8ft 10in across all course types over the four year test period. Again there was a distinct difference between parkland and links with parkland greens averaging 8ft 3in compared with 9ft 3in on links courses. Average green speeds have increased over the last ten years, which is positive, but there is still room for further improvement. We must be careful not to focus on this characteristic alone, but there is a need for average green speeds to improve further if the game is to become more enjoyable. This is particularly important on parkland courses.

4. Greens that show average volumetric moisture content (VMC) values below 30% tend to show higher proportions of fine grasses. Conversely greens with VMC values regularly above this threshold tend to show higher proportions of Poa annua. Thus wetter soils, and factors that promote wetness may tend to favour Poa annua.

5. Average firmness across both main course types is still lower than we would like. Admittedly 2012 was a wet year but this data has been collected over four years and shows that 42% of links courses and 57% of parkland courses are meeting the target levels of firmness (target ranges for the two types of course are different i.e. higher for links). However it should be noted that those clubs who have been on the programme for four years show a marked improvement against target figures.

6. Organic matter levels in rootzones beneath greens are too high and are also the cause of poor performance in the firmness data. 10% of parkland courses and 15% of links courses meet the 0-20mm STRI depth target, with levels generally having crept upwards in 2012.

In summary

The STRI Programme, which records and collects data and benchmarks golf greens, has been extremely valuable and as it continues over the next few years will yield further interesting information and no doubt show further progress for those involved. However there is no hiding the fact that the data as a whole shows a need for further improvement. We must improve in all surface performance categories, but particularly in the areas of organic matter management and firmness. How this is achieved is the key question, but our belief is that performance measuring in a regular, structured manner should help protect the nation’s greenkeepers, and their courses, and provide the evidence to allow them to do their jobs unimpeded by short term agendas.


Reader Comments

On March 21st, 2013 John Chapman said:

An excellent article. Alastair has been working closely with Mark Heveran at Royal Cromer and provided great advice.

On March 21st, 2013 Brian Ward said:

An excellent piece which should be required reading for all head greenkeepers and greens chairmen.

On March 26th, 2018 Steve Turrell said:

Hi there great article, really informative. Is there any links to actual performance quality standard tables in golf? or does each course differ rather than creating a standard structural quality, presentational quality or playing quality, I was really interested to know if there is meant to be an average height of cut to produce a certain ball speed/bounce etc???
Thanks Steve, it might be worth your while to read the Turf Fox’s article on ‘green speed new facts’

On September 4th, 2018 John Spraggs said:

A very good read

On January 19th, 2021 * TEST* Rolling Greens – Jeffrey Kaye's Turf 1000 Reflective Journal said:

[…] How to Measure Green Speed – Golf Tip Greens measurement […]

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