As with metal ores, it is useful to be able to calculate exactly what proportion the essential nutrients accounts for in a fertiliser. Ammonium nitrate (NH 4 NO 3) is commonly used as a fertiliser.

Nitrate fertilisers can be made through neutralisation reactions. To complete this, a supply of nitric acid is required. Nitric acid is then used to make ammonium nitrate which is high in nitrogen.

However, nitrate is also recycled within sediments by dissimilatory nitrate reduction to ammonium (DNRA). Understanding the factors that influence the balance between denitrification and DNRA is thus ...