Assessing our nitrogen inheritance

摘要: A new challenge from a past solution Human perturbation of the nitrogen cycle represents major example global geo-engineering. Historically, limited availability reactive compounds has provided key constraint to human activities. Although element is extremely abundant, making up 78% Earth's atmosphere, it exists mainly as unreactive di-nitrogen (N 2 ). By contrast, be useable by most plants and animals, r ) forms are needed. These include oxidized reduced compounds, such nitric acid, ammonia, nitrates, ammonium organic each which normally scarce in natural environment. The two main historical needs for have been provide fertilizers increase food production basis manufacture munitions. Biological fixation always added into system, but inputs barely sufficient needs. As result, traditional agricultural was highly dependent on effective recycling manures. end nineteenth century, an increasing population combined with expanding military required that large amounts extra circulation. demands were met increased mining deposits, including Chile saltpetre guano, supplemented extraction coal peat (Vincent, 1901; Clow Clow, 1952; Watt, 2003; Sutton et al ., 2008).