O N reduces water use , nitrogen loss , and moss growth in a container nursery

verhead irrigation is the most common form of irrigation in forest and conservation nurseries (Landis and others 1989) and in greenhouse production overall (Leskovar 1998). Overhead irrigation systems are generally less expensive to install, and have the advantage of preventing the accumulation of fertilizer salts that can be detrimental to plant growth (Argo and Biernbaum 1995). A significant disadvantage, however, is that overhead irrigation can be fairly inefficient—in a reforestation nursery between 49% and 72% of the applied water was discharged from the nursery (Dumroese and others 1995). Because nursery and greenhouse production use higher rates of fertilization than do other agricultural crops (Molitor 1990), this discharge water can have significant amounts of unused fertilizer in it (Juntenen and others 2002; Dumroese and others 2005) and be a potential source of groundwater and surface water pollution. McAvoy and others (1992) found high amounts of nitrate in the soil below greenhouses. Several states now impose restrictions on the amount of wastewater that can be discharged from nurseries (Grey 1991), and some states are imposing restrictions on the amount of water that can be O