Modelling nitrous oxide emissions from agriculture once fertilizer leaves the field

Countries need to keep track of their national greenhouse gas emissions in an effort to meet targets to combat climate change. Even though carbon dioxide gets most of the attention, nitrous oxide is the most potent of the top three greenhouse gases that contribute to current global warming, having 300 times the warming strength of carbon dioxide. In many countries agriculture is the largest source of nitrous oxide emissions. Keeping track of these emissions after they leave the farm fields via water pathways is difficult.

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Nitrogen: Blessing and curse

The chemical element nitrogen (N) is an essential building block of all life on Earth and represents the fourth most common element in biological organisms, including us. Because of its importance for plant growth and food production humans have doubled the natural input of available nitrogen to our ecosystems, with adverse effects on the environment and our health. This surplus of nitrogen led to the expansion of the dead zones in the Gulf of Mexico and Baltic Sea, the concentration of the potent greenhouse gas nitrous oxide is increasing in the atmosphere and infants suffer from high nitrate concentration in the drinking water. Schlesinger describes in his article where all the nitrogen ends up that we humans produce for fertilising our fields. He also warns that our knowledge of the nitrogen cycle is still limited and that nitrogen accumulation in unexpected places will lead to environmental deterioration.

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