Organic matter v material

Added on December 22nd, 2015 by Lorne Smith
Posted in General, Greenkeeping

Organic matter v organic material


Travelling around GB&I and visiting golf courses purely as an amateur player but also talking to greenkeepers about what they are trying to do, I pick up the sentiment that ‘all-year-round firmness’ in greens is becoming a major objective – Hoorah!

FineGolf is not suggesting it has all the answers to the complex question of achieving all-year-round firmness, which continues to baffle even the experts but we believe it is worth trying to identify from an independent viewpoint what are the issues with the different approaches.

Digging a little deeper and reading lots of greenkeeping monthly magazines where grass consultants write articles on how to achieve this ‘firmness’, there does seem to be an increasing emphasis on the need to

top-dress greens with tons of expensive pure sand.

This apparently not only smoothes the greens for better putting but it also, in greenkeeping parlance, “dilutes the thatch layer”.

thatch, jim arthur, fescues,

High thatch rootzone

‘Thatch’ is a combination of soft cellulose and woody lignin that results from dead grass and roots and other ‘organic material’, such as leaf stalks etc, which reside in the rootzone, just below the living grass.

In natural greenkeeping, the equal balance of good bacteria and fungi in the ‘organic matter’, or humus, within the soil around the grass roots, ensures the successful breakdown and degradation of the dead thatch (organic material), turning it back into nutrients for the drought-resistant, deep rooted fine grasses. This process requires good aeration and the grass being cut at above 4mm so the natural plant food-chain grass system remains friable and drains well, which the perennial fine grasses love and stay disease free.

In chemical controlled greenkeeping however, the natural nutrient uptake is swamped and overridden by inorganic fertilisers and the weed grasses, primarily annual meadow grass (Poa annua), cut below 4mm (some greens being cropped as low as 1.75mm) become stressed, needing extra water and fertiliser. In addition, the weed grass grows quicker dosed with fertiliser and becomes prone to excessive fungal disease and thatch build-up.

If this thatch layer (organic material) becomes too thick it is either too mushy, holding excess moisture or becomes the very opposite, creating a barrier to moisture reaching the shallow weed grass roots. (Water management products like wetting agents ameliorate these problems in the short term but fail to solve the underlying thick thatch problem).

Therefore thatch build-up needs to be controlled if the objective of ‘all-year-round firmness’ is to be achieved.

Everybody desires this outcome apart from a few diehard 2mm Poa brigade greenkeepers with high input budgets who produce ‘target-golf’ greens.


This vital goal of controlling the thatch is delivered in one, or more, of three ways:

1)     Mechanically – using machinery like a ‘Graden’ or ‘hollow coring’ with all the concomitant disturbance to golfers if undertaken during the summer season when the growing grass recovers quicker.




2)     Top-dressing – diluting the thatch layer with many tons of pure sand, which runs the risk of burying a problem as an impermeable layer, restricting aeration, draining and deep root growth.




3)     Increasing the microbial and fungal activity to naturally convert the thatch layer (organic material) to humus and acids that slowly feed the continually evolving natural grass food chain. A healthy balanced soil is created with the ‘organic matter’ giving a medium for good bacteria and fungi to thrive and do their work. The use of ‘Compost Teas’ is one way of boosting this activity.







A side effect of using pure sand top-dressing and hollow-coring infill is that this action creates the perfect inert environment into which weed grass (Poa anuua) can invade, enjoying the artificially high fertilised environment containing a high bacteria and low fungi balance. Pure sand dressings also increase the risk of poor moisture retention and can place unwelcome demands on irrigation in dry parts of the country.

Mycorrhizae, Mycorrhizal

Mycorrhizae around grass roots

The soil biology one seeks is one where mycorrhizal fungi attach to fine grass roots and help extend their feeding root system while good microbial activity boosts the natural defences to disease.

So it is the creation of ‘organic material’ not ‘organic matter’ that is part of the larger problem and if the two similar phrases continue to be mixed up by advisors to greenkeepers, the solution to how to move from soft weed grass to firm fine grass will be further confused.

The science of soil biology in golf has become better understood through research conducted at many universities and the technology developed by Symbio in recent years, since Jim Arthur died in 2005. To promote further interest in this area FineGolf has hosted some articles by Martin Ward MD of Symbio, although we note that the STRI, the largest agronomic service company, who earn considerable income from hosting grass trials for all sorts of companies and providing laboratory soil analysis to golf clubs with weed and fine greens, don’t yet seem convinced of the proof of the efficacy of compost teas.

jim arthur,

Jim Arthur at Notts(Holinwell)

Perhaps it is useful to return to Jim Arthur and his instinctive understanding of natural greenkeeping which he saw as much an art as a science and who continues to give the simple non-chemical way forward. He was happy with links courses using top spit sand and seaweed mixed, as top-dressing, while advising use of 70/30 sand/fensoil as a replacement dressing for courses using high silt clay content mixed with sand.

The provision of some ‘organic matter’ within the rootzone where healthy microbes and fungi can live in competition against the pathogens that thrive in high fertilised environments that produce disease, clearly must be a good policy.

However, as in all healthy activity there is seldom one solution that fits all and the correct answer depends on the particulars of the specific site.




Practical Greenkeeping, Jim Arthur

Practical Greenkeeping by Jim Arthur

FineGolf continues to recommend that golf clubs do not trust the snake-oil salesmen of the high input fertiliser and pesticide brigade but rather to check out your problems and solutions by reference to Jim Arthur’s bible of natural greenkeeping ‘Practical greenkeeping’.

If a golf club is contemplating going through a change from managing Poa to introducing fine grasses, take advice from the experts who have a track record of this change. Only engage them if they recognise that it is not just the technical advice that is necessary but also positive communication and involvement with the club’s membership to build an understanding of the vision of where and how to get there. This will ensure long term success.

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