Date of Award

5-2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Committee Member

Dr. L. B. McCarty, Committee Chair

Committee Member

Dr. V. L. Quisenberry

Committee Member

Dr. B. R. Smith

Committee Member

Dr. L. R. Hubbard

Abstract

Soil physical characteristics of golf courses, greens, and fairways, include many factors determining play quality. The United States Golf Association (USGA) has developed extensive guidelines that address many course issues, but various concerns remain, drainage often being the main problem. Sand capping is often suggested as a solution for problem drainage areas on fairways. This work addresses the question of how thick a sand cap must be. Several methods have been proposed to determine an adequate depth with nearly all these methods using some form of a soil moisture retention curve (SMRC) and its air entry point. SMRCs were run for four sand mixes, and the curves used to determine the depth of sand necessary to achieve given volumetric soil water content and aeration porosities. These methods provided suggested sand depths ranging from 4 cm to greater than 35 cm. No method seemed to yield a reliable, reasonable, and scientific based depth. A more reasonable approach is suggested: determination of an equivalent depth of water required to saturate a given depth of a sand cap. Thus, if a golf course or sports field superintendent wants a sand cap that can hold 5 cm of rainfall, and will allow play to continue, its required depth can be determined using a SMRC. All sand cap depths estimations in this work should be considered worst-case conditions: 0 cm tension at the lower cap boundary. With tensions at the boundary of 10 or 20 cm, a great more pore space exists for water storage. For example, for a sand cap depth of 15 cm and 0 tension at the lower boundary, 0.3 cm of water will saturate the cap. With 10 and 20 cm tensions at the boundary, a cap hold 2 cm and 4.5 cm of water respectively. Additional work indicated: 1) small amounts of fines (clay and silt) can be added to sand mixes without detrimental effects on water flow properties; 2) several new USGA recommendations for green specifications are questionable; and 3) the zone with the lowest hydraulic conductivity in a golf green is near the surface, in the thatch layer.

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