Evaluation of Temporal and Spatial Dynamics of Water Movement in Sand-Based Construction Systems.

Increasingly, golf course and sports fields around the world are moving toward sand-based root zone construction for ensuring optimal playability, performance, and longevity of turfgrass playing surfaces.  Ideally, sand is placed atop a constructed drainage layer that allows rapid lateral movement of excess water to drainage lines.  Sand capping without a drainage layer offers a lower-cost option that is gaining in popularity, especially on golf courses and athletic fields in situations where low water quality and/or heavy soils necessitate rapid drainage and ability to flush salts.  While the dynamics of water movement in fields constructed with a drainage layer beneath the sand root zone has been well studied, it has not been in fields capped with sand directly over soil. The objectives of this study were to evaluate temporal and spatial dynamics of water movement in sand capped fields, and to demonstrate how these dynamics vary from those in a field constructed with a drainage layer.  A field study was conducted in 2015 and 2016 at the Texas A&M Turfgrass Ecology Field Laboratory in College Station, TX.  Measurements of water content and water tension were made after irrigation in the sand root zones of small test plots constructed with and without drainage layers.  The results demonstrated that that there are appreciable differences in water movement in the sand root zones of fields constructed without a drainage layer compared to those constructed with a drainage layer, and that these differences were predictable, knowing the hydraulic properties of the soil beneath the sand capped plots.