One of the key elements to any sustainability strategy is the procurement of local materials from local suppliers. Sourcing locally contributes to the economy of your region, supporting nearby businesses who supply and those that deliver. It also drives down the carbon footprint of long-distance haulage, and the potential waste of lost material during transport. There will also be a cost benefit to be had through buying locally, as haulage can cost at least as much as the materials themselves. This has clear implications for new golf developments or existing facilities considering the reconstruction of a number of poorly performing putting surfaces.
There are a number of documented processes for building a golf putting green that an architect or an agronomist will default to if asked to specify a construction method. These are, however, prescriptive in terms of the make-up and depth of the rootzone and underlying drainage systems, with recommended ranges of mechanical parameters that the sand, organic amendment and gravel have to achieve. Whilst providing some insurance as to the drainage capabilities of the end product, each is limiting in terms of the source of suitable sand and gravel, with local materials being rejected in many instances because they do not comply with the documented process. This has resulted in many greens being built in the spirit of the recommendations, but using materials that have to be transported from some distance and that may perform to the extremes of the guidelines, which often results in failure. Finding ideal sands, organic amendments and gravels which comply with these methods can be a problem in many parts of the world where these finite resources, to the specification demanded, are becoming scarce locally, resulting in supplies having to be transported from greater distances, adding significantly to the cost and carbon footprint of the project.
All materials used to build a green must be laboratory tested to ensure they are suitable.
The R&A is proposing a new approach to golf green construction, and one that is being applied to the development of our new Equipment Test Centre, where golf clubs and balls are tested to see if they conform with the Rules of Golf, together with being a facility for research into all aspects of the sport. Finding a local source of materials, or as local as possible, for your golf green construction should be your starting point. However, this must not compromise on the quality of the finished product, which must be assessed in accordance with climatic conditions (how much rain or drought will it have to cope with), laboratory analysis on performance factors, and the turfgrass type with which is to be established. All construction methods are compromised if the rootzone is capped with an incompatible soil brought in with imported turf, if this is the method used to establish a grass sward. So, the grass establishment method is vitally important, as is post-construction management. Once established, grass and its natural organic deposition can, even if managed well, reduce the drainage potential of a construction by as much as 90%. If poorly managed, there can be a 99% reduction in drainage potential and a complete failure of the construction and the turf.
The process to determine how such a sustainable green would be built should take the following path:
- Employ a qualified turfgrass agronomist to advise on material selection, to organise laboratory testing, to interpret the results, to confirm the type of green construction most appropriate for your circumstances, to monitor the construction process and to assess its performance post-construction.
- Identify the necessary performance criteria for the putting surface in terms of how quickly it needs to drain or to what degree it needs to be able to retain water. Take care when assessing drainage rates as any construction that can cope with monsoon rains may not be capable of growing grass without massive quantities of irrigation. In such a situation, excessive amounts of fertiliser will be required to get grass to grow. This is not just costly, it is a waste of water and fertiliser, can result in pollution as nutrients leach through the rootzone, and if you are successful in holding a grass cover, it will be prone to rapid thatch accumulation and the soft, spongy and disease-prone turf that is a consequence of such management.
- The end product needs to be taken into consideration, i.e. how you want the green to play. The design of the course dictates how approach shots to the greens will be executed and, consequently, how the desired firmness of the greens. The construction technique will impact on this, as will the selection of grass and how it is managed. A conscientious designer will keep this in mind from right from the very start of the project.
- Investigate the site and weather conditions to determine if materials in situ may be suitable. For example, on links the local sand may be ideal. Light textured soils may be fine if amended with more sand, which will need to be imported. On sites where the soil is heavy in nature, it will be necessary to replace this with imported materials, but these should be sourced as locally as possible.
- This approach should also determine the need for a drainage system, identifying key elements such as the suitability of local gravels, the drainage layers required, the design of the pipe or other water evacuation system, and potential positive outlets and falls.
- Allied to the point above is the need to determine whether the construction method should incorporate a perched water table or should it provide more predictable and constant conduction of water through the rootzone into draining subsoils or drainage carpets.
- If it is necessary to import materials for the rootzone, identify sands in the locality which may be suitable.
- Identify local sources of organic matter or other amendment which comply with certified standards for blending with the sand.
- Submit samples for testing to a laboratory which has American Association for Laboratory Accreditation (A2LA). The key tests to ask for are particle size analysis, lime content, total porosity, air-filled porosity, capillary porosity, percolation rate and saturated hydraulic conductivity.
- The samples should be tested to ascertain how deep the approved blend needs to be laid down in order to meet the performance criteria for a golf green rootzone.
- If a drainage layer or layers are required, identify gravel(s) in the locality for testing at a laboratory which has American Association for Laboratory Accreditation (A2LA).
- The gravel should be assessed by the laboratory for its compatibility with the selected rootzone blend. The key tests to ask for are bridging factor, permeability factor and uniformity factor and, as for the rootzone, an assessment will need to be made on the depth of gravel required and if a blinding layer is required to ensure optimum performance.
- Grass selection is critical for the production of a quality playing surface which can be achieved through the efficient use of resources. Those best adapted to the local climate and the quality/quantity of the available water supply for irrigation should be favoured.
- Choose a grass establishment method which will not compromise the construction, in terms of its drainage capability. Seed, sprigs, washed turf, turf grown on a material compatible with the selected rootzone or cores extracted from greens grown on a compatible material are all suitable options. Avoid bring in turf or cores grown on a soil which is incompatible with the rootzone.
The construction and grow-in stages of a putting surface are critical to its long-term and sustainable success. However, ongoing maintenance can make or break a good construction. Organic matter must be well managed so as not to witness a level of deterioration in drainage that will result in failure. The R&A recommends ongoing monitoring of performance throughout the lifetime of a putting surface, which should include the agronomic parameters of organic matter content and soil moisture content, as well as playing performance characteristics; firmness, trueness, smoothness and speed.
Whilst our guidance will widen the options for material selection, it may well result in the selection of one of the documented putting surface construction methods for any particular project. The key is that the method chosen suits the site, its climate, the desired performance outcomes and locally available materials, as opposed to selecting materials to suit the construction method.
Throughout the process, professional advice is critical to support decisions on the selection of materials.
The R&A utilise the services of the Sports Turf Research Institute (STRI) for its agronomic advice and soil laboratory testing, including consultation on the construction of putting surfaces at the new Equipment Testing Centre.