Iron-cemented layers in soils of golf putting greens.

Layers cemented by iron have been observed in the soils of golf course putting green across the USA. The layers result in reduced water infiltration, saturated conditions in the root zone, and a decline in turfgrass quality and density. The physical and chemical properties of these layers have not been characterized in turfgrass soils. Six sites with cemented layers were sampled and these represent a range of geographic locations and climatic conditions. The cemented layers were found at the lower interface of organic-rich topsoils, or at the interface of sand and gravel. Levels of total Fe in the cemented layers ranged from 0.4 to 16.2 kg ha^-1_, and these were accompanied by accumulations of soil organic C and sometimes Mn and Al. These cemented layers meet the criteria of the placic horizon in Soil Taxonomy. The downward movement of water, high levels of iron, and a textural discontinuity are key factors in the formation of the cemented layers, which may become cemented in less than 10 years.