Physical Properties of Sand as Affected by Clinoptilolite Zeolite Particle Size and Quantity

Little is known about how the particle size of amendments influences the physical properties of amendment-sand mixtures. In two laboratory experiments, the amendment clinoptilolite zeolite (CZ) was used to amend sand at two sand:CZ ratios of 5 and 10 (w/w) and six CZ particle sizes, including: >1 mm, 1 to 0.5 mm, 0.5 to 0.25 mm, 0.25 to 0.105 mm, 0.105 to 0.047 mm and <0.047 mm. Saturated hydraulic conductivity (SHC) ranged from 3 to 48 cm hr¯¹, decreased with the decreasing CZ particle size which was most noticeable at the finest CZ particle size. The water content of CZ-sand mixtures at soil matric potentials from -3 kPa to - 10 kPa increased with decreasing CZ particle size. Bulk density of the CZ-sand mixtures (except for CZ-mixtures < 0.047 mm) ranged from 1.37 to 1.42 g cm¯³, which were significantly (p = 0.01) lowered than the unamended sand (1.48 g cm¯³) . Sand amended with 10% of the finest CZ particle size had the lowest total porosity (41.5 g Kg¯²). Aeration porosity (at -3 kPa soil matric potential) of the mixtures containing coarse CZ particles (>0.25 mm) ranged between 35 and 38% (v/v), similar to the unamended sand. In humid regions where higher SHC is necessary for good drainage and aeration, CZ particle sizes >0.25 mm would be desirable to amend a sand of this nature. However, in arid area where water is limited, sand could be amended with finer CZ particle sizes (0.25-0.047 mm) to increase water holding capacity of the putting green root zone media while still maintaining a moderately high SHC.