TECHNOLOGY: URBAN GOOD SPORTS FIELD CONSTRUCTION CAN CUT WATER USE IN HALF AND ENSURE TURF SURVIVES DROUGHT SNAPSHOT • Sand can be a good material for sports field construction if certain criteria are met. • However, unless an underlying gravel layer (known as a perched water table) and quality soil amenders are used, sand can result in various issues, including higher irrigation requirements and low resilience to drought. • The perched water table approach is also expensive and complex to implement. • Often a better approach is to amend the existing soil at a site, which can result in lower irrigation requirements and greater carrying capacity.
Many in the industry believe sand is the ideal material for a sports field due to its excellent drainage properties. However, sand is not good at retaining water or nutrients, and can be an unstable surface if particles are uniform in size and/or rounded in shape. Here, Dr Mick Battam and Dr Paul Lamble discuss the requirements when constructing sports fields with sand, and the mistakes that are often made along the way. They outline other viable approaches such as the amendment of existing topsoil, which is often a cheaper strategy that allows turf to thrive with less water.
Overcoming the limitations of sand Internationally adopted guidelines, such as the American Society for Testing and Materials (ASTM) Standard Guide for Construction of High Performance Sand-Based Rootzones for Athletic Fields (F2396-11) and The United State Golf Association’s (USGA) 2018 recommendations for putting greens, establish specific criteria for the performance of sand profiles. The guidelines stipulate that sands must meet precise requirements regarding particle shape and size distribution, in addition to possessing a minimum water holding capacity of 15 to 25 per cent. To meet these requirements, two conditions must be met: 1. The sand must be laid over a gravel layer – an approach known as a perched water table design. This enables the sand to hold more water than if it were laid directly over soil, which would suck the moisture out of the overlying sand (the field capacity principle). 2. Amenders must be applied to the sand. The USGA lists suitable amenders as peat, mature composts and zeolite. The ACT guidelines (published by the ACT Government) also approve the use of coir. On some high-profile racecourses, the growing media consists of a mixture of 70 per cent sand and 30 per cent soil, which is laid over gravel. This enables adequate moisture storage while allowing excess water to drain away rapidly through the growing media. Many believe that sand is the best material for a sports field, but often amending the existing topsoil is a better approach, which can allow turf to thrive with less water.
10