Formation of Clay Lamellae in Golf Course Soils of Mississippi, USA.

Clay lamellae have been observed in the sand putting green soils of a golf course in Mississippi. These layers result in reduced water infiltration, saturated soils, and decreased turfgrass density. The soils featured A horizons of 4 to 5 cm, mixed A/C horizons of approximately 10 cm, and C horizons of about 30 cm over gravel. The soils were constructed in 2005 with 90% quartz sand and 10% (by volume) sand-sized calcined clay over a subgrade of compacted subsoil. Clay lamellae were observed at the interface of sand and gravel, with the exception of a soil profile directly above a drain pipe. Clay contents in lamellae ranged from 1.7 to 3.4 percent. We proposed three hypotheses to explain the formation of these lamellae: 1) clay was present in the sand and moved downward, 2) clay originated from the breakdown and subsequent translocation of the calcined soil amendment used during construction, or 3) clay from the underlying compacted subgrade moved upwards through the gravel and into the sand. In each hypothesis, clay accumulated at the boundary of sand and gravel due to preferential retention of water in the sand above the gravel. X-ray diffraction showed that the lamellae contained kaolinite and quartz, whereas the calcined soil amendment contained illite and no kaolinite. The underlying subgrade soil contained kaolinite, quartz, and hydroxy-interlayered vermiculite. Discriminant analysis of x-ray fluorescence spectra showed that the clay fractions of these three different samples had unique fingerprints. These findings suggest that the lamellae did not likely originate from the calcined soil amendment or the subgrade soil. They most likely originated from translocation of clay that was initially present in the sand. This study provides evidence for formation of lamellae in less than 10 years, and provides an example of accelerated soil formation due to anthropogenic factors.