Management of surface hydrophobicity and subsoil sodicity in sand‐capped turf systems

Abstract Sand‐capping of golf courses and sports fields is becoming a common practice, especially in high rainfall areas or where irrigation water contains elevated sodium that has degraded native soil over time. While sand‐capping can provide improved playing conditions, unique management issues may develop over time in these systems including loss of subsoil permeability due to Na, accumulation of surface organic matter, and/or development of surface hydrophobicity. The objectives of this study were to evaluate individual and combined effects of gypsum and wetting agent application programs on mitigation of surface hydrophobicity and subsoil sodicity in sand‐capped Tifway bermudagrass ( Cynodon dactylon × C. transvalensis Burt. Davy) systems. Studies were conducted over 2 years on sand‐capped plots ranging in depth from 5 to 20 cm. Results demonstrated that capping depth played a critical role in overall turfgrass quality, percent green cover, soil water relations, and development of surface hydrophobicity, with shallower capping depths (5 and 10 cm) outperforming deeper capping depths (20 cm) for almost all parameters. While wetting agent applications helped to increase surface soil moisture, they were only beneficial for deeper capping depths, as little to no hydrophobicity was observed with shallower capping depths. Results also showed that a single yearly application of a high rate (490 g m −2 ) of gypsum was more effective than 10 monthly low‐rate (49 g m −2 ) applications at reducing subsoil sodium adsorption ratio under high Na‐irrigation water.