What are the main sources of Nitrous Oxide emissions?

Human-related sources are responsable for 96% of nitrous oxide emissions. The almost all of the emissions are coming from the following 3 sources:

• Artificial Soil Fertilization
• Mobile/Stationary Sources of Fossil Fuel Combustion
• Livestock Manure

Figure 1:Source: Inventory of U.S. Greenhouse Gas Emissions and Sinks (2008), EPA.

• Artificial Soil Fertilization:

  Crop fertilization has been called the great saviour of humanity. Aside from increasing crop yields to help feed a human population that keeps on growing it is assumed to help farmers by increasing their profits. Sadly both of these statements are false. Not only has the rates of malnutrition and famine risen but our over-use of synthetic fertilizers and pesticides has resulted in overall decreases of usable farm land.

  As for the myth of increased profits, the largest recuring annual expense for farmers is for synthetic fertilizers and pesticides. While there are small increases at harvest time, there is a heavy strain on the soil itself as well as on the quality of the food produced. These synthetic chemicals are absorbed by the plants which are then absorbed by us. Apart from this it takes a lot of energy/electricity to create synthetic fertilizers and pesticides so their impact on climate change is actually larger when we factor this in.

• Mobile/Stationary Sources of Fossil Fuel Combustion:

  Fossil fuel use is again a major contributor to the emissions of another greenhouse gas. When any fossil fuel is burnt it creates nitrous oxide emissions. The majority of stationary emissions of N₂O come from coal fired power plants. As for mobile emissions of N₂O, almost all of it comes from the passenger cars and trucks that are used to transport people and goods. This is because catalytic converters are designed to promote the emissions of N₂O even though it is a powerful greenhouse gas that can trap almost 300 times more heat than CO₂.

• Livestock Manure:

  Nitrous oxide is also emited when the organic nitrogen in manure and urine decomposes. So places like poultry, beef and dairy cattle farms produce significant amounts of N₂O. Because of this industrialized farming practices are the most important source of N₂O emissions. It would be easy to blame farmers for this current situation but consumers have to make demands on the market if there is to be any change from what has become the norm.

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