Soils with iron-cemented layers on golf courses in the USA

a r t i c l e i n f o Layers cemented by iron and manganese have been observed in soils of putting greens at golf courses throughout the USA. They result in reduced water infiltration, saturated conditions in the root zone, and a decline in turfgrass density and quality. The physical and chemical properties of these layers have not been investigated nor described in detail. Here we present a detailed analysis of the physicochemical properties and a conceptual pedogenetic model for the formation of Fe-cemented layers in soils of golf putting greens across the USA. These man-made soils have an A horizon of about 5 to 10 cm over 20 to 30 cm sand (C horizon) over gravel. The Fe-cemented layer is commonly found at the interface of the A and C horizons, or the C horizon and the gravel layer. Levels of total Fe in the cemented layers range from 0.41 to 16.21 g kg −1 and these are accompanied by accumulations of SOC and sometimes high levels of Mn and Al. The downward movement of water (irrigation), high levels of Fe (fertilization), and a textural discontinuity are key factors in the formation of the Fe-cemented layer. The layers may form at rates as high as 1.5 mm per year depending on Fe content and redox conditions in the root zone, and may become cemented in 10 years. These cemented layers meet the criteria of the placic horizon in Soil Taxonomy. Most soils in urban areas have been altered by human activities including moving, draining, paving or other forms of disturbance. In recent years, there is an increased interest in the soils of urban areas which is primarily driven by studies on pollution and environmental issues (e.g. Andersson et al., 2010; Li et al., 2013). Considerable research on urban soils is also conducted in relation to peri-urban and urban agriculture (Materechera, 2009; McClintock, 2012). Lawns and gardens often receive inputs (including fertilizer, water, and pesticides) and such soils have been significantly disturbed, but comprise the natural soil of the area. Soils of golf course putting greens also receive inputs but these soils are constructed like the soils of mine spoils; the materials are excavated, transported, and repositioned across the landscape. In the USA, there are over 16,000 golf courses (Beard, 2002) covering a land area of approximately 4850 km 2 (Throssell et al., 2009). On a typical …