It is now known that lightning helps greatly to fertilize the soil. Eighty percent of the atmosphere or sky is nitrogen, an essential food for plants. About 22,000,000 tons of this nutriment float over each square mile of the earth. But as it exists in the atmosphere nitrogen is unusable by plants. Before plants can take life from it, it must undergo a series of chemical changes, very much as food in our digestive system must undergo changes. Lightning in the sky touches off the series of changes. Air particles are made white-hot by lightning, for it can heat a two- to ten-inch channel of air hotter than the sun's surface. Under this intense heat, the nitrogen combines with the oxygen in the air to form nitrogen oxides that are soluble in water. The rain dissolves the oxides and carries them down to earth as dilute nitric acid. Reaching the earth, the nitric acid reacts with the minerals of the earth, there to become nitrates on which plants can feed. Since plants can feed and live, man and animals can feed on plants and live!
