Page 11 - GM Fall 2025 flipbook

Look at Organic Matter
Surface Performance
Figure 2: A depth scatterplot illustrates the variation in OM values across multiple greens,
capturing data at all three depths simultaneously.
involves cutting cores at 2 cm
increments while leaving the turf on
(see Figure 1). To ensure a depen-
dable average, collect a minimum of
five sub-samples from each area
sampled. Be sure to avoid atypical
areas—such as entry and exit
pathways, bunker splash zones, and
shaded spots—that might skew the
representation of the green’s overall
condition.
The choice of sampling tools also
plays an important role. A 3/4 inch
sampler or larger is effective, provided
it can pull a straight uniform core.
Once collected, the samples should
be dried immediately to halt biological
activity before sending them to a
laboratory equipped for OM246
testing like Brookside Laboratories.
Unlike standard soil tests,
OM246 samples are not ground or
sieved upon arrival at the laboratory,
as undecomposed OM like thatch
influences surface firmness. Samples
are burned at 440°C – higher than
the typical 360°C used in
conventional soil tests – to accurately
measure total organic content. It is
essential to have samples sent to labs
equipped for OM246 testing.
MAKING SENSE OF THE DATA
Let us say a superintendent receives
their OM246 results: 6.4% OM at 0–2
cm. What does that mean? Is that
high? Low? Without context, it’s
difficult to tell. That is where data
visualization becomes essential.
OM246 results are best interpreted
using visual tools that add context and
clarity to raw numbers. Two key
formats that are particularly useful are:
1. Scatterplot Comparisons
(see Figure 2)
A depth scatterplot shows how OM
values compare across multiple greens
at all 3 depths at a single point in time.
The grey background dots on Figure 2
represent data from other golf courses
and can be used to determine
provincial averages for each depth.
Over the past two seasons in British
Columbia, the averages have been:
• 0-2 cm: 5.8%
• 2-4 cm: 2.5%
• 4-6 cm: 1.9%
OM is produced at the surface; a
trend reflected consistently in the
depth averages across the scatterplot.
The coloured dots represent specific
greens at a course of interest. It is a
helpful starting point to see what the
highest vs lowest OM surfaces are and
how they compare to the provincial
average.
Usually, large full sun greens have
higher OM than smaller shadier greens.
We look at the range of OM especially
at the 0-2 cm depth and ideally, we
have a narrow range at a desired value.
A narrow range suggests consis-
tency across greens whereas a wide
range indicates variability. Whether a
golf course has a wide or narrow
range, the end goal is to achieve
consistency at a desired value.
GreenMaster • CGSA •
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