The extensive root systems and long growth seasons of energy crops make them very suitable for environmental solutions and recultivation projects. The Danish Institute of Agricultural Sciences has carried out measurements (cf. figure below) that show that leaching under energy crops is basically equivalent to levels for natural vegetation and forest. At the same time, willow and elephant grass are able to survive on poor soils. Factors such as salt resistance, nitrogen level, pH value, toxic chemicals and general soil conditions are vitally important in selecting the correct variety.