Nitrogen: Too much of a vital resource

Nitrogen (N) is a key nutrient, vital for the survival of humans and all other living organisms. While di-nitrogen gas (N2) is abundant in the atmosphere, most organisms are unable to use this chemically unreactive form. First it must be converted or fixed߿ݠinto a reactive form such as ammonia (NH3) or nitrogen oxide (NOx). These and other forms...

Nitrogen footprints: past, present and future

The human alteration of the nitrogen cycle has evolved from minimal in the mid-19th century to extensive in the present time. The consequences to human and environmental health are significant. While much attention has been given to the extent and impacts of the alteration, little attention has been given to those entities (i.e., consumers,...

Consequences of human modification of the global nitrogen cycle

The demand for more food is increasing fertilizer and land use, and the demand for more energy is increasing fossil fuel combustion, leading to enhanced losses of reactive nitrogen (Nr) to the environment. Many thresholds for human and ecosystem health have been exceeded owing to Nr pollution, including those for drinking water (nitrates), air...

A chronology of human understanding of the nitrogen cycle

Nitrogen over the ages! It was discovered in the eighteenth century. The following century, its importance in agriculture was documented and the basic components of its cycle were elucidated. In the twentieth century, a process to provide an inexhaustible supply of reactive N (Nr; all N species except N2) for agricultural, industrial and...

A nitrogen footprint model to help consumers understand their role in nitrogen losses to the environment

The human use of reactive nitrogen (Nr) in the environment has profound beneficial and detrimental impacts on all people. Its beneficial impacts result from food production and industrial application. The detrimental impacts occur because most of the Nr used in food production and the entire amount of Nr formed during fossil fuel combustion are...