Posted: 20/08/2014 at 22:17
You need actual lightning (ie a large spark) to split Nitrogen molecules (N2) into two separate atoms (N) as a lot of energy is required: N2 is very stable and unreactive until you split it by heating to several thousand degrees. The single atoms of Nitrogen will then combine with nearby Oxygen molecules to form Nitrate (N03) and Nitrite (NO2) which dissolve in the rain to form weak Nitric acid.
A far more efficient method is used by plants which can fix Nitrogen directly from the air by using enzymes which are almost magical in their ability to do this using far, far, lower levels of energy. We are talking thousands if not millions of times more efficient.
If you want to make your own Nitrates in the most efficient and ecologically friendly way possible, simply grow plants and stew them in cold water until they are broken down (again using enzymes) by naturally occurring bacteria. Life has been perfecting these processes for billions of years and has become extremely efficient at it!