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Moisture vs OM

Organic Matter, Soil Moisture and Bowls Green Performance

Last time I revealed the results from an experiment I did to establish the percentage of Organic Matter (OM) in 3 very different greens. My hypothesis says that there is a link between Soil Moisture and Bowls Green Performance. To recap, one of these greens was a natural seaside links type green with a good homogenous sandy loam all the way down the profile with no layering and just a little thatch near the surface.

The second green was a 20 year old green that was built to USGA specification using a quarry sand and local sandy loam topsoil. This green, although boasting a nice homogenous rootzone mix, was showing signs of excessive thatch (organic material) build up at the surface.

The third of our greens was a typical push up type green, simply made from local (quite heavy) soil and suffering as a result of that and decades of inappropriate maintenance and now showing a high percentage of Organic Material, much of which was probably mat and thatch at the surface and only partly decomposed Organic Matter in layers within the deeper profile.

By homogenous, I mean that the soil is a well mixed combination of Mineral Material and Organic Matter throughout the depth of the soil profile. There are no distinct layers in the soil profile, it is a completely mixed material and it isn’t possible to distinguish between the Organic and Mineral components by sight alone. To achieve this, the Organic Matter has been completely decomposed by the soil micro-organisms into a state known as Humus. This material is a critical component of a healthy, living bowls green as it provides a mechanism for moisture and nutrient retention in the soil.


Prior to doing what is termed the Loss on Ignition test to ascertain the Organic Matter content of these 3 soil samples we had also undertaken firmness tests with the Clegg Hammer and these showed that the greens that were higher in Organic Matter content, were less firm and so less likely to provide a true and smooth bowling surface.

You might remember what the graph looked like of Firmness against Moisture content from my earlier article. Here it is again:

Measuring Bowls Green Surface Firmness

You can see from the chart above that there is a very clear correlation between moisture content and firmness. When moisture goes up, firmness (and of course smoothness/trueness) reduces.

So far I’m not revealing anything you don’t instinctively know, but let us now look at

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