Understanding Organic Matter Testing

Organic_Matter_Black_Layer

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.