Organic Matter Management

Understanding Organic Matter Testing


As I have written about before in a previous post, the build up of thatch or organic matter is one of the most important if not the most important aspect of our roles as turf managers in consistently maintaining high quality playing surfaces across many sports disciplines, but has our knowledge and understanding of it and it’s management changed over time?

There are countless research, articles and opinions available when it comes to organic matter management, yet it still remains and will continue to remain a dominant issue in our maintenance and renovation programs. Through accurate assessment of organic matter, the turf industry’s knowledge of its development and maintenance is evolving.

Using devices like the Trufirm (pictured above) or the Clegg Hammer, the turf manager can accurately measure the firmness of their respective playing surface and track the progress over time. Maintenance programs can then be modified where necessary to achieve the desired results.

Using devices like the Trufirm (pictured above) or the Clegg Hammer, the turf manager can accurately measure the firmness of their respective playing surface and track the progress over time. Maintenance programs can then be modified where necessary to achieve the desired results.

Failure to deal with organic matter and allowing it to increase, results in a long list of negative consequences to the playing surface and the turf health, such as:

  • Reduced surface firmness

  • Reduced soil infiltration rates

  • Higher moisture retention

  • A more favourable environment for disease development

  • More favourable conditions for pest activity

  • More favourable conditions for moss, algae and other weeds

  • Increased Poa annua content

  • Decreased tolerance to play during frosty conditions

  • Reduced playability during wet conditions

  • Reduced playability during the Winter months

  • Increase in pitch mark severity

  • Decrease in root length

It doesn’t matter if you are the turf manager, club manager, financial controller or club owner, excessive or increasing levels of organic matter is not good for the long term health of the facility. For some clubs this may be a contributing factor and for others it could be the root cause of their biggest maintenance challenges and poor playing quality experienced by the players.

However, knowledge, awareness and understanding of organic matter and its management has increased in recent years and when understanding increases, it becomes apparent where past shortfalls in dealing with it have been present.

It is difficult to visually measure the organic matter content in a diluted soil profile accurately.

It is difficult to visually measure the organic matter content in a diluted soil profile accurately.

Quantifying Organic Matter

The industry has been quantifying its organic matter levels through various methods for a number of years. For the most part, these methods have been largely unquestioned and have included low, moderate and high opinion based observations or, in recent years, reviewing its depth in millimetres.

Such methods were fine in years of low costs and plentiful budgets, but we are in a new era now, and accurate decisions year on year are required by club managers, boards of directors and even committee members. These periodic ‘guestimates’ often fail to provide suitable/accurate information on which serious and costly decisions can be made.

Clubs are spending thousands of dollars every year on sand top dressing and renovations to deal with organic matter and this does not include the labour hours and bespoke machinery required for organic matter management. We are now seeing a hunger for accurate, objective information on which to base the decisions turf managers are making on behalf of their clubs.

Testing Organic Matter Concentration via Loss on Ignition (LOI) at 440 Degrees Celsius

Organic matter can now be measured using laboratory testing via weight loss on ignition. We prefer to use LOI at 440 degrees celsius as it gives more of a full burn, with no visible signs of organic material remaining and feel it is more accurate as opposed to LOI at 360 degrees. This testing method enables course managers and clubs to determine their exact levels of organic matter at varying depths in the soil profile year on year. Such testing, combined with onsite experience and surface performance targets allows the turf manager to clearly identify the target area or organic matter level in the soil, then create and tailor a cultural program to achieve the clubs surface performance targets over time

Soil samples being tested for organic matter content by loss on ignition

Soil samples being tested for organic matter content by loss on ignition

Organic Matter Accumulation at Differing Depths

With an ever increasing arsenal of machinery and tools to manage organic matter content, knowing exactly how much is present at exact depths is of high importance and financial consequence to clubs.

The nature and depth of organic matter can vary from course to course, and even green to green, and visual assessments are not always able to pick up such variations, unless present in extremes, by which point it is often too late and is causing a notable difference in the quality of the playing surface.

By breaking samples into pre­determined depths (0-20, 20-40, 40-60mm) exact percentages of organic matter can be determined at each 20mm depth in the soil profile. On request, we can even measure depths of 0-10mm or deeper at 60-80mm if required.

This allows us to determine the exact percentage content at each depth, establishing clear strategies for management programmes to be determined, optimum selection of machinery used and avoidance of any unnecessary works and labour hours.

The bulk concentration of organic matter accumulation is usually contained within the upper 0-40mm with Poa annua and ultra dwarf bermuda grasses tend to have organic matter production concentrated in the top 0-20mm. Most turfgrasses tend to produce organic matter through 0-40mm of the soil profile. 

As clubs move to deal with organic matter quickly and achieve improved playing surfaces, layers of buried organic matter at 20-50mm deep in the profile, are becoming more common. These layers cause a lot of the issues listed earlier in the article including reduced infiltration rate and shorter root length. Where possible, light applications of sand top dressing should be applied regularly with quantities adjusted as per the growth rate of the turf with the aim to dilute the organic matter through the profile and avoid the creation of layers.

The Value of LOI Organic Matter Testing

Our industry is evolving. For many of us, budgets have reduced, and now as never before, has spending it wisely been so important. The need for course managers and clubs to allocate and spend their resources accurately has never been higher.

Through LOI testing, decisions can be formed accurately and annually. Where resources over and above our normal budgets are required, clear and concise communications can be had within our clubs, providing clearer levels of understanding.

Knowledge of long term results and requirements to get from your existing levels of organic matter to bespoke ideal ranges can now be costed accurately, budgeted years in advance and scheduled in long term plans. With the technology available now, turf managers can now accurately measure every performance characteristic of their surface and diagnose almost all turf health issues and make decisions based on this objective data; this is a position the industry has not been in before.

If you are interested in LOI organic matter testing, please see our analytics page for more information or contact us for special offers.

2018 Course Renovations @ Nikanti Golf Club

The 2nd of April saw the beginning of the annual course renovations for Nikanti Golf Club. The aim of the process was to remove the excess organic matter that has accumulated over the last 12 months, relieve any compaction and present the surfaces in top condition for the clubs biggest event of the year, the BMW Golf Cup which begins on the 10th of May.

We have created a set of Course Quality Objectives for the club which include target ranges for various performance parameters including firmness, green speed, infiltration rate and soil organic matter levels. These parameters are aimed at maintaining a high performing playing surface consistently through the year. 

Renovation practices like what we completed this year and in previous years, allow the club to achieve those goals and target specific areas that have been identified as underperforming. Since incorporating the Course Quality Objectives, the main focus during renovations has been removing the maximum amount of organic matter from the fairways. The fairways are harbouring a dense organic matter layer at their surface which holds excess moisture and results in a softer surface.

Soil organic matter levels in the greens were tested by Loss on Ignition at three different levels. 0-20mm, 20-40mm and 40-60mm. From these results, we could effectively target the problem area for maximum results. The test results showed that the OM levels are still within the target ranges. The decision was then made to use a solid tine rather than a coring tine and focus the verti-cutting on the top 5mm of the soil to remove the OM which had accumulated over the previous 12 months. The club will also incorporate more regular verti-cutting and dusting in their regular program through the year.

A step by step video of the golf course renovation practices at Nikanti Golf Club in 2018

Below is a summary of the program in chronological order for all surfaces including approximate costs. 


  • Vertical mow at -5mm up and back on the same line in 3 directions
  • Double cut at 3mm
  • Aerate with 9.7mm solid tines in a 1.5" x 1.5" pattern
  • Top-dress by hand
  • Level lawn when the sand has dried
  • Double roll
  • Brush with a medium-soft hand broom
  • Apply fertiliser and irrigation. Ammonium sulphate (21-0-0) and Eon 75 (humic acids)

After 4 days...

  • Vertical mow at 0mm
  • Aerate with 6.3mm solid tines in a 1.5" x 1.5" pattern
  • Brush with a medium-sof hand broom
  • Apply fertiliser and irrigation. Mono Ammonium Phosphate (12-60-0), Potassium Nitrate (13.5-0-44) and a retention wetting agent.

Approximate costs (initial 2 days):

  • Sand = US$1238.71 (60m3)
  • Labour = US$1,043.98 (31 staff)
  • Tines = US$1,045.20
  • Fertiliser = US$616.88 (21-0-0 = $36.23 + Humic Acid = $580.65)


  • Vertical mow at -5mm up and back on the same stripe in 3 directions (Triplex)
  • Graden at -5mm in 1 direction (collars and other small areas)
  • Double cut at 9mm
  • Top dress
  • Aerate with 9.7mm solid tines in a 1.5" x 2" pattern
  • Rub in with coconut drag mat
  • Heavy roll
  • Apply fertiliser and irrigation. Ammonium sulphate (21-0-0)

Approximate costs:

  • Sand = US$1,48.39 (75m3)
  • Labour = US$811.69 (25 staff)
  • Tines = US$537.10
  • Fertiliser = US$45.29


  • Circle cut at 7mm
  • Graden in 1 direction at -20mm
  • Drag with a steel mat (after Rak-O-Vac)
  • Cut at 7mm in 1 direction
  • Top dress
  • Rub in sand when dry with a coconut mat
  • Apply fertiliser and irrigation. Ammonium sulphate (21-0-0)

Approximate costs:

  • Sand = US$9,290.32 (450m3)
  • Labour = US$503.05
  • Fertiliser = US$271.74


  • Cut from 40mm to 20mm
  • Top dress and aerate high traffic areas with 16mm coring tines in a 2.5" x 2" pattern
  • Rub in with a steel drag mat when dry
  • Apply fertiliser and irrigation. Ammonium sulphate (21-0-0)

Approximate costs:

  • Sand = US$412.90 (20m3)
  • Labour = US$226.2
  • Fertiliser = US$301.94


Tees were completed two weeks later as part of our regular maintenance routine. The program below is completed on the tees every 4 weeks and has provided fantastic results allowing the club to forgo a major renovation.

  • Cut at 5mm
  • Light top dress
  • Aerate with 6.3mm solid tines in a 1.5" x 2" pattern

Approximate costs

  • Sand = US$495.48 (24m3)
  • Labour = US$78.13 (5 staff @ US$1.56/hour)
  • Tines = US$508.10

A huge thank you to the team at Nikanti, it was a tough week but they did an expert job allowing us to finish on schedule with a fantastic result.

Please feel free to contact me if you have any questions regarding any of the processes above.

2017 Course Renovations

From the first week of April we began our course renovation practices which would include re-landscaping some large focus areas. We were lucky enough to have the course closed for 10 days as there were also some maintenance scheduled on the clubhouse.

This was a big opportunity to go a little more aggressively in some areas (predominately the fairways and approaches) than we have done in the past and will allow us to achieve the surface performance standards that we have been targeting.

It was also great to have Nigel Taylor stop by on the first day to see how we were doing and to take some great footage of the process.

A chat with Nikanti Golf Club Director of Golf Course Maintenance, Brad Revill about his annual course renovations.

Thanks for that Nigel! If you haven't already seen it, check out Nigel's Vlog on Youtube. He gets to visit some pretty amazing courses around South East Asia and meet the Superintendents who are responsible for them.

I have also made my own video chronicling our renovation process below

2017 Course Renovation Program:


  • Vertical mow at -5mm in 2 directions up and back on the same line
  • Blow off debris and cut at 3mm with a firm brush in front of the mower
  • Topdress
  • Wait for sand to dry and then aerate with 10mm solid tines at a 1.5" x 1.5" spacing
  • Use the coco fibre mat and hand brooms to work the sand into the holes
  • Heavy roll
  • Fertilise with 21-0-0 @ 100Kg/Ha + Eon 75 (Humic Acid) @ 60Kg/Ha
  • Irrigate
  • 3 days later - Aerate with 6mm solid tines at a 2" x 2" spacing
  • Double roll
  • Fertilise with 18-22-5 @ 140Kg/Ha
  • Irrigate


  • Cut at 5mm
  • Topdress
  • Wait for the sand to dry and hen aerate with 12mm solid tines at a 2" x 2" spacing
  • Use the coco fibre mat to work the sand into the holes
  • Heavy roll
  • Fertilise with 15-15-15 @ 200Kg/Ha
  • Irrigate


  • Cut at 7mm
  • Scarify with the walk behind Graden at -25mm
  • Clean up debris
  • Topdress
  • Wait for the sand to dry and then aerate with 12mm solid tines at a 2" x 2" spacing
  • Use the coco fibre mat to work the sand into the holes
  • Heavy roll
  • Fertilise with 21-0-0 @ 160Kg/Ha
  • Irrigate


  • Circle cut at 7mm
  • Aerate with 16mm coring tines
  • Aerate and topdress using the Koro Recycling Dresser at -125mm
  • Separate the sand from the debris with a steel drag mat
  • Blow off and collect the debris
  • Brush in the sand
  • Heavy roll
  • Fertilise with 21-0-0 @ 120Kg/Ha
  • Irrigate


  • Cut from 40mm to 25mm
  • Cut from 25mm to 20mm
  • Fertilise with 21-0-0 @ 120Kg/Ha
  • Irrigate

We are also in the process of re-landscaping the majority of the out of play areas on all 18 holes in an effort to reduce maintenance and frame the hole. During the closure we managed to plant 25,000 Red Fountain Grasses (Pennisetum rubrum) along hole 18 and we are currently half way through planting 27,000 Lemon Grasses (Cymbopogon spp.) along hole 1 and 6. 

A huge thank you to my team and the 120 caddies that came to assist us with the landscaping!

If anyone has any questions, please feel free to ask anytime!

The End of Coring?

Organic matter management. Probably one of, if not the most important aspect of our role as turf managers in consistently maintaining high performing playing surfaces.

Do we need to core greens? Can we manage organic matter with sand top dressing and the use of solid tines only? How much sand is needed and how often do we need to apply?

It is these questions I often ponder about on my 1-2 hour daily commute home from work each evening. Over the last 6 months, I have taken advantage of this commute time to listen to all the podcasts from TurfNet Radio and in particular, Frank Rossi's "Frankly Speaking" episodes. If you haven't yet discovered the TurfNet Radio podcasts, I highly recommend them.  It was one of these episodes in particular with Frank and guest Dr. Roch Goussoin who was the head of the Agronomy Department at the University of Nebraska, talking about managing organic matter in fine turf that first opened my eyes to at least the possibility that we didn't need to core! A possibility that I would never have thought of before as it is engrained into us that we core aerify and top dress in the Spring and Autumn to control organic matter build up and relieve compaction, amongst other benefits.

Negotiating the mayhem that is Bangkok

Dr. Roch discusses the survey that they conducted in 17 states and on over 200 golf courses over almost 3 years in an attempt to identify which greens consistently had the lowest organic matter and why. He explains that the results show that for all the greens that were surveyed, the dominating factor for the greens that had the lowest organic matter percentage was the amount of sand applied over the growing season, not necessarily if they cored or didn't core or how frequently or aggressively they pulled a core, but the amount of sand applied followed by the frequency in which they top dressed.

Dr. Roch then conducted a 2 year study to determine if the way you make a hole matters and if it was possible to manage organic matter with top dressing only. All test plots (180 altogether!) received the same amount of top dressing sand with different cultivation techniques including coring, no coring, solid tining, bayonet tines, planet air, hydrojecting and also looked at greens of different ages. He then goes on to say...

...we basically proved that core aerification does not lower organic matter any more then not pulling a core or using a solid tine.

Wow! This made me start to question everything we were doing in regards to managing organic matter. This theory was further backed up by Dr. Norm Hummel in another episode with Dr. Frank Rossi, titled Aerating and Topdressing High Performance Putting Surfaces. Micah Woods also has some interesting thoughts of managing organic matter and biomass in this blog.

Great, so was there anyone who has actually had any success trialling this approach? Luckily enough, Chris Tritabaugh, the Superintendent at Hazeltine National and recent host of the Ryder Cup, talks about his management techniques in this episode and the fact that he has not pulled a core since August 2013! He only uses deep solid tines, needle tines and dryjecting in combination with regular topdressing through the growing season to manage organic matter. I think it's safe to say that nobody was questioning the quality of surfaces that were presented for that event!

I also read an article titled "Unconventional wisdom" in the January 2017 GCM Magazine where Jamie Kizer who was the Superintendent at Hidden Falls GC, Texas had only core aerified his greens once in the past 7 years. He utilises a biological approach, brewing and applying compost teas to stimulate microbial activity in the soil combined with the use of the Air2G2 machine to inject air directly into the soil profile once per month to further stimulate the microbes and digest the organic material.

Irrelevant practice??

So is this the end of coring? I personally think there will always be a place for core aerification as a tool for compaction relief and to remove excessive organic matter in combination with machines like the Graden. But once we have that excessive organic matter removed, it makes sense to me that we should be able to keep it sufficiently diluted with regular sand topdressing, solid tining and/or in combination with a biological program and Air2G2 machine.

We do not have an Air2G2 at Nikanti Golf Club but with our last core aerification in June 2016 and average OM% sitting at 1.2% (Nov. 2016) in our 4 year old greens, we will definitely be testing the topdressing and solid tining approach moving forward. 

This OM% figure is taken from a sample depth of 100mm when we do our regular soil fertility testing. I would like to send some samples away in the next month that are taken from the top 5cm of the soil which I think will be much more relavent.

Current profile of our 2nd green

It was my hope to present you with some data on our cultural practices, fertiliser applications and performance data in this post but I admit I have not finished compiling the 2016 data. This just means you will be hearing from me again on this matter very soon. I will leave you with a quote from my first boss and Superintendent at Bermagui Country Club, David Thomson, which will stick with me forever...

When we stop evaluating everything we practice, that’s the time to leave the trade.