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Inorganic soil amendments have been suggested for use in turf to alleviate soil compaction, increase water retention and hydraulic conductivity, and improve many other soil physical properties. Many types of soil amendments have been used under various climate conditions and for different purposes, and the results are mixed. There is a need for systematic investigation of the physical properties of root-zones affected by soil amendments and construction methods. The stability of sand or soil amendments has been a concern when the media is subjected to weathering. The chemical and physical effects and seasonal freezing/thawing involved in the weathering process have significant impact on the physical properties after construction. This information is needed in the design process to improve performance characteristics of soil media. Unlike golf course greens, sports turf fields require a more stable playing surface to facilitate play and avoid player injuries. Many athletic fields have adapted a sand-based root zone system to avoid compaction and poor drainage. However, sand-based systems may be unstable. Research on the roles of inherent properties of sand in playing surface stability has been limited to evaluations of particle-size distribution. Although sand shape and roundness are considered to be an important component of surface stability, their roles relative to other factors still are not clearly understood because of the technical difficulties involved in quantitatively assessing these characteristics. The overall objective of my research is to gain a better understanding of the physical properties, such as water conductivity, water holding capacity, and porosity of sand-based media affected by soil amendments, either as root-zone mixtures or as topdressing materials. Specific objectives include the investigation of the changes of those soil physical properties over time, comparison of the effects of green construction methods (flat green vs sloped green) on these physical properties, and quantitative evaluation of particle shape and roundness. In a flat green study, porous ceramic clay (PCC), calcined diatomaceous earth (CDE), polymer coated clay (PC), and ceramic were used in the top 15 cm root zone at 10% (v/v) rate. The control contained 5% (v/v) peat. The treatments were applied in completely randomized block with three replications. Data collected on the flat green included saturated hydraulic conductivity (Ksat), water retention, water release curves, bulk density and total porosity on compacted samples collected at construction and undisturbed samples collected from the treated plots one and two years after establishment. The PCC treatment had an 8 and 7% higher cation exchange capacity (CEC) than the control in 1997 and 1998, respectively. The PCC increased Ksat by 26 and 20% in the compacted and undisturbed samples, respectively, in 1998. The CDE increased water retention by 13% in both compacted and undisturbed samples. Hydraulic conductivity of the sand/inorganic mixtures decreased over the two years, although some increase in hydraulic conductivity were observed each spring. In a laboratory study, inorganic soil amendments were mixed with sand, repacked in a cylinder and compacted to certain bulk density according to the USGA specification. The samples then were saturated, frozen, thawed for 0 to 20 cycles to simulate freeze/thaw effects. It was found that after 20 freeze/thaw cycles, sand amended with PC had a 7.6% decrease in bulk density from the compacted sample. The percentage weight of the finest fraction that passed through the 0.106 mm sieve to the bottom pan increased due to freeze/thaw cycles in zeolite, clinoptilolite and lapillus treatments compared to the sand control. After 20 cycles of freeze/thaw, Ksat values of sand amended with PCC and CDE were 25 and 33% higher than the control, respectively. Twenty freeze/thaw cycles resulted in 24.7 and 16.2 cm h"1 increases in Ksat of the sand amended with PC and CDE, respectively. The increases of Ksat by PC and CDE are likely due to their bulk density decreases. The sloped research green (SRG) contained a 7.0% slope facing north, a knoll, a 6.6% slope facing south, and a swale (the low portion to the south end of the green). The green was seeded with 'Crenshaw' creeping bentgrass (Agrostis palustris Huds.). The topdressing treatments included 80% sand and 20% peat (v/v), PCC, CDE, zeolite clinoptilolite, and zeolite clinoptilolite preloaded with fertilizers (ZPF). Turf color and cover quality were evaluated in 1999 and 2000 during the growing seasons and before and after two cycles of dry down treatments in the four areas on the green. During most of the growing season in 1999, ZPF treatment showed better turf color and coverage. This advantage was lost during the irrigated recovery period that followed two periods of water stress. It is possible that the extra 49 kg ha"1 of N in ZPF could have made turf quality appear better during most of the summer, but also predisposed the grass to more drought injury as was evident from the lower quality ratings during the water stress period. The low turf quality of ZPF in the spring of 2000 could have been caused by toxicity from Na and K which were 47.7 g kg"1 and 557.7 g kg"1 in the 0-2.5 cm of root zones, respectively. We did not find benefits of inorganic amendments used as topdressing materials to prevent dry patch problems on a sloped green. In the study of sand shape and roundness evaluation, mason sand, concrete sand, silica sand, crushed brick, and crushed stone were used to cover a wide range of shapes and

Physical properties of golf and sports turf root-zones as affected by amendments, construction methods, and management practices