When I teach about turfgrass maintenance, much of the discussion involves putting greens or other highly trafficked turf areas, because that is where most of the shots are played. And I am invariably asked questions about the type of sand to use, whether river sand can be used, or what type of amendments should be mixed with sand, and so on.
These are important questions, and I have six things that I usually talk about when these questions are raised.
1. Sand is a terrible medium for plant growth because sand has a low water holding capacity and low nutrient content. Plants, including turfgrasses, will generally grow better in soils containing some silt and clay than they will in sand. Of course, with regular maintenance, turfgrass managers are able to produce excellent turf in sand rootzones through the provision of water and nutrients to meet the plant requirements.
2. However, a sand can be chosen that has two especially useful characteristics for high traffic turf areas. With the right particle size distribution, sands can be used that have a) a rapid infiltration rate, so that the surface is usable soon after a heavy rain, and b) resistance to compaction, even though there is a lot of traffic on the area. Infiltration rate and resistance to compaction — those are the reasons sands are used for high traffic areas.
3. There are very specific recommendations for putting green construction provided by the USGA. This document, USGA Recommendations for a Method of Putting Green Construction, is freely available (http://bit.ly/USGA_green). These are sometimes called the “USGA specifications” and they outline everything from the depth of sand to the type of drainage to the sand particle size and various physical properties that the sand must have if the green is to meet the specifications set out in the USGA Recommendations document. Make variations from these Recommendations, and the green may still perform well, but please don’t call it a “USGA” green if the Recommendations are not followed.
4. For topdressing sands, a good starting point is to look for sands that have physical properties that meet USGA Recommendations.
5. I don’t think the Method outlined in the USGA Recommendations is necessarily the best way to build a green, but it is one that works, and it is a way to build a green that many people understand and know how to manage. Figure 1 shows the construction of a USGA green in Krabi, Thailand in 2006, and Figure 2 shows the same green still performing well in 2014. That type of predictable result is what we expect when building a green to USGA Recommendations.
6. If I were building a putting green for myself, and if I knew that I would be the one to manage it, I would probably build a green with some soil in it, with lots of surface drainage, with a slower infiltration rate than in the USGA Recommendations. But if I were building a green for someone else, and I knew that I would not be responsible for maintaining it, I would choose the USGA Recommendations. That way, the risk of unexpected problems is much reduced.
I encourage everyone to download a copy of the USGA Recommendations and to be familiar with the document. Many problems and confusions could be avoided by a broader understanding of this Method.