I found this dialogue online concerning your question: "DB: I'm Deborah Byrd. JB: And I'm Joel Block for Earth and Sky, with a listener's question. "Why does my grass look greener after a lightning storm? Is it true that lightning acts like a fertilizer for plants?" DB: Lightning can help produce a form of nitrogen that's useful for growing plants. Lightning can cause oxygen and nitrogen in Earth's atmosphere to combine -- to form nitrogen oxide -- the main nutrient in lawn fertilizers. But that's not the whole story -- does the nitrogen oxide created during a lightning storm really cause your lawn to look greener? JB: And the answer to that is probably no. Lightning produces nitrogen oxide -- but storm winds generally blow it thousands of kilometers away. What's more, it can take days for the nitrogen oxide created in a lightning storm to wash down to the ground. Nitrogen oxide produced in a storm does add nutrients to the soil -- but only much later and in places far from where the storm took place. DB: So if your grass looks greener after a thunderstorm, you might want to consider a different explanation. It might be because of the extra rain -- and the quick return of sunshine. That's our show for today. Thanks for joining us. If you want to ask an Earth or sky question, come to our web site at earthsky.org. I'm Deborah Byrd. JB: And I'm Joel Block for Earth and Sky." http://www.earthsky.com/shows/show.php?date=20050522

EFFECTS OF LIGHNING ON GRASS Lightning makes grass and other plants greener because it is good for them. Lightning does help produce a form of nitrogen that is useful for growing plants. What happens is lightning causes oxygen and nitrogen to combine and form nitrogen oxide, a key ingredient in many fertilizers. (http://wiki.answers.com) Does the nitrogen in lightning turn grass green? In: Thunderstorms and Lightning Yes. Lightning provides the intense energy needed to combine atmospheric nitrogen and oxygen into nitrates. The rain then carries these nitrates down to the earth's surface enriching the soil. Acting as a fertilizer, nitrates in an indirect way helps make the grass green.