A Guide to
Drainage
golf on it! As soon as a golfer sets foot on a golf
green it is compacted a little bit. The more people
play golf on it the more it is compacted. When
soil is compacted all the particles get squashed
together so there are no spaces between them.
Particularly since most soil particles are irregular
or angular in shape they nestle into each other.
It is these spaces which allow water to move
through the soil so if there are no spaces there is
no drainage. Even if a good piped drainage system
has been installed, if the water can’t move through
the soil to get to the drainage pipes it will not drain.
This is why greenkeepers put so much effort into
keeping the soil aerated to maintain a more open
There are three types of water in soil. soil texture.
‘Hygroscopic water’ surrounds, and is held tightly
to the surface of soil particles. It is held so tightly,
partly because of electrolytic action, that it is
unavailable to plant roots. ‘Capillary water’ is held
in the spaces between particles and is available
to plant roots. ‘Gravitational water’ is passing
between the particles draining through the soil by
gravity. Eventually in a free draining soil this water
will be replaced by air.
Before this gravitational water drains away all
the pore spaces are full of water and the soil is said
to be ‘saturated’. If the only water in the soil is the
hygroscopic water unavailable to plants the soil is
so dry it has reached ‘wilting point’. Between these
two conditions is the ideal state and the soil is said
to be at ‘field capacity’.
SOIL WATER
Thus at field capacity in a well-structured,
organic, well aerated soil we have the necessary
conditions for healthy plant growth.
Sadly in the case of sportsturf, in spite of the
best efforts of groundsmen and greenkeepers to
create and maintain these perfect conditions, we
go and spoil it all by playing sport on it!
For example golf course drainage, especially of
greens, would be much easier if people didn’t play
That is why all golf greens should have sign saying
“Please Keep off the Grass”!
To put it into perspective a 70/30 rootzone
material will have an infiltration rate of up to
800mm/hour, a normal sandy loam will be as low
as 100, a clay soil only 50, but a compacted clay
soil is virtually nil.
www.rugbyclub.biz
13