Your grass isn’t likely greener because of lightning. That isn’t to say that there isn’t some logic – and science – behind the possibility. It just isn’t likely.
And recall that unlikely does not mean impossible.
Going back to Chemistry class
Before we get to the greener part, we have to think back to Chemistry class. And back to Earth Science class, too.
The Nitrogen molecule (N2) makes up about 78-percent of the atmosphere. Oxygen (O2) is another 20-percent is Oxygen. Argon (AR) is about one-percent. And the rest of the atmosphere is composed of Methane (CH4), Carbon Dioxide (CO2), Water Vapor (H2O), and ‘other’ stuff.
Plants, like humans, love nutrients. One of the big ones needed for healthy plants is nitrates – which is one Nitrogen atom combined with two Oxygen atoms. Nitrates are found in a lot fertilizers. That is why manure does such a great job at greening up stuff – it is full of nitrates and phosphates.
As an aside: This is also why composting is so good. With composting, a portion of the Nitrogen molecule in the compost pile is “volatilized” as NH3, and a small amount may be emitted as N2O. The remainder is found either in the bodies of microorganisms as organic N, or as NO3, which is available to plants.
Manure is a good way to get nitrates, but a way cooler (or hotter, I suppose) way is using lightning.
Yeah! Lightning!
The heat from a lightning bolt can split the Nitrogen molecule (N2) in half leaving two Nitrogen atoms, instead of one Nitrogen molecule of two atoms – floating around. If, after splitting, one of those Nitrogen atoms has a positive charge, it can attract three Oxygen atoms to bond with it. That makes a Nitrate: NO3.
Plants love NO3.
After the lightning bolt splits the Nitrogen up, and it bonds with the oxygen, that new N03 is charged. It holds a negative charge.
Water, H2O, is a polar molecule and has both a positive and negative charge (that’s why it is good at cleaning stuff, btw). Then, since the nitrates are water soluble, the NO3 just dissolves into the water. And it falls out with the rain.
How would this help plants?
When the nitrogen-rich rainwater falls, it soaks into the ground and is then available for the plants to soak up. Because it is either nitric acid or apart of the rain itself, it can get pulled up by the roots of the grass easily.
Or, at least, that is the claim.
Indiana Public Media, at Indiana University breaks it down:
That available nitrogen is what could help green up the plants.
A lot of people think this works
From Chicago’s favorite meteorologist, Tom Skilling, to the TV show, “NOVA” on PBS. The science it pretty straight-forward. Plus, the results can be seen. People can simply look out into the yard.
And “seeing is believing,” right? (Well, it isn’t. But I’ll save that post for another day)
Maybe not completely. There may be some confirmation bias at work, too. For example, maybe someone heard that this lightning-Nitrogen thing made grass green. Then, after a two-week drought, they look into the backyard after it storms and the grass looks greener.
“Must be the extra nitrogen,” the person says.
Except, after two weeks of no rain, the grass was probably browning up anyway. And covered with pollen and dust. When the rain came through, it washed all of that pollen and dust off of the grass. And made it look greener.
Or, it could be something else.
But there are skeptics
No one questions the logic or the science. More so the timescale. A lot of people claim that, as little as, an hour after the thunderstorm the grass is visibly greener.
That transformation may be something a bit simpler.
“What’s most beneficial for the grass this time of the year is the water. The rainfall itself that’s falling. It’s a nice uniform watering with natural rainfall. And the green response you see after a thunderstorm is probably mostly due to the rain itself,” University of Arkansas associate professor of horticulture Doug Karcher told 4029tv.com
Even on longer timescales, it may be something different, too. Jennifer Knoepp, a research soil scientist with the USDA Forest Service, SRS, Coweeta Hydrologic Laboratory in Otto, North Carolina added her two cents in an interview with mnn.com:
“As plants grow, their small roots die and new roots grow. When that happens, soil microbes cause the dead roots to decay. Think of this process as similar to adding compost to your lawn, only this action takes place underground and naturally, without your intervention.
The roots are made up of large chemical compounds consisting mostly of carbon but also some nitrogen. Soil microbes use carbon and some of the nitrogen to cause the dead roots to decompose. As this happens, a portion of the nitrogen is released back into the soil as a sort of waste product.
As rain soaks into the soil, it activates the microbes to release more nitrogen. The grass benefits from the freshly fallen rain because the flush of water allows the roots to take up this “new” nitrogen as well as the nitrogen that the microbes have previously released. At the same time, “the grass is very active with photosynthesis” when the sun returns,” Knoepp told mnn.com.
So, even if there isn’t a lightning connection, Nitrogen may still be a big influence.
It may be a bit of both
Truly, it depends on the timescale, too. Did it just thunderstorm an hour ago, and now your grass is greener? Probably just the new water. Did it thunderstorm before sunrise in the morning, and your grass looks greener that afternoon? That might be the extra nitrogen from decaying plant material and lightning.
But, it can’t be known for sure unless soil samples are taken and research is done on a specific plot of land. But nitrogen deposition from lightning is a thing. And it is possible the new nitrogen in the soil could be responsible for the extra green lawn.
Or it could just be the rain that fell.
And since water is a bigger decider on if grass is green or not, I would lean more toward it being the water that did it, rather than the lightning.
