Sports
fields are usually constructed on sand-based root zones which provide an ideal
medium for turf systems with respect to physical characteristics. However, sand has low water and nutrient
holding capacity. Modification of the root zone by applying amendments provides
a potential for enhancing water and nutrient retention. Addition of organic
amendments such as peat helps to increase water and nutrient retention, but
peat decomposes over time, reducing air-filled porosity. Inorganic amendments offer
a number of benefits for improving water and nutrient retention and since an
ideal putting green root zone is expensive to build,
their resilience also helps to delay reconstruction. However, little
information is available on their effects on root zone. We investigated
physical, and hydraulic properties of seven inorganic amendments marketed in
the southeastern United States.
These were zeolites (Clinolite
and Ecolite), calcined
diatomaceous earth (Isolite and Axis) and fired clays
(Moltan plus, Profile, and Pro's choice). The properties
analyzed were bulk density (BD), particle density (PD), porosity, particle size
distribution (PSD), saturated hydraulic conductivity, water retention (WR) and available
water-holding capacity (AWC). The AWC is defined as the difference between the
permanent wilting point (PWP) and field capacity (FC). We divided the AWC into
easily available water-holding capacity (EAWC), moderately available
water-holding capacity (MAWC) and less available water-holding capacity (LAWC).
The PD of the amendments ranged from 2.18 to 2.44 g
cm-3 which is lower than that of sand (2.67 g cm-3). However, most particle sizes
ranged from 0.5 to 2.0 mm, which is comparable to that of coarse sand. The zeolites had the least suitable physical and hydraulic
properties, while the calcined diatomaceous earth had
the best. Axis showed the best physical and
hydraulic characteristics; i.e. highest AWC, and total
porosity (0.79 cm3cm-3), and low PD (2.20 g cm-3)
and BD (0.47 g cm-3).