Turfgrass archaeology

This soil profile, showing how the soil has been modified after about 70 years of management as a golf course putting green, is absolutely fascinating. This photo is from a course in Sydney, Australia. Because this hole is now closed for a complete renovation, the superintendent decided to make some archaeological researches by digging down to the original dune sand that the green was built on. Click on the photo above to get a full size image for closer inspection.

Starting from the bottom of the profile, we can see the clean sand that is the original dune, meters deep, that the green was planted on. Moving up, we see darker material at the base, this probably being some organic material that was mixed in the soil at the time of planting the green. Then we start to see distinct layering, dark and then white bands moving horizontally across the profile; these would be the bands of sand topdressing laid down at annual renovations, as the scarifying-aerifying-topdressing activity is often referred to in Australia. And we start to see aerification holes, filled with sand from decades ago, still providing vertical channels through the soil profile.

Moving up through the central part of the profile we can see perhaps a change of topdressing sands, perhaps some periods when more coring was carried out, and less topdressing sand was laid down, and then nearer the surface we see even more coring holes filled with sand, and what appears to be a higher organic matter content, still diluted with sand, but perhaps less so than lower in the historical profile.

This profile is one of the most interesting things I’ve seen on a golf course, and it helps to remind me that the maintenance work we do on a daily basis will have an impact on how water, nutrients, and air (and consequently roots) move through the soil profile for years to come. Also, that there can be layers and discontinuities of various sorts in a rootzone, and the grass can still grow well. Layers are not always a bad thing.