Impermeable Lamellae Formation In Two-Tiered Golf Course Putting Greens.

Two-tiered golf course putting greens drain quickly after large rainfalls, yet supply water to the turfgrass over a long period of time. This is accomplished by the two-tiered design: a layer of sand overlays a layer of washed pea stone, and this creates a perched water table that does not begin to drain until the sand layer reaches saturation. These drainage events occur often in areas that receive regular rainfall, but rarely in more arid regions. A unique problem has been witnessed in the two-tiered putting greens of two golf courses in Hawaii and  Vietnam. At the sand-gravel interface of the putting greens, mineral lamellae have formed that impede downward water flow and result in anaerobic soil conditions in the root zone and deterioration of turf quality. This problem develops rapidly; the golf course in Hawaii was experiencing this issue within five years of construction. The lamellae have been characterized mineralogically by x-ray diffraction and chemical analysis. Formation of the lamellae is presumed due to iron chemistry at the textural discontinuity and associated redox conditions, where iron is derived from either the component sand and pea stone or from iron sulfate treatment of the turfgrass.