|by James C. Thomas
Many high performance putting greens and athletic fields are designed
and built based on the USGA recommendations which call for placement of
a 12 inch deep uniform root zone mixture over a gravel drainage blanket.
The root zone mixtures are carefully chosen mixtures of sand and organic
amendment designed to have a specific particle size distribution, saturated
hydraulic conductivity, and pore space distribution. These properties
are chosen to provide resistance to compaction plus excellent drainage
and aeration to promote optimal turf growth. For these systems to perform
correctly, it is important that the root zone mixture be as uniform as
possible from top to bottom since the presence of layers of differing
materials will interfere with the desired water and air movement through
the root zone.