As the saying goes, April Showers bring May Flowers, but what do March showers bring us? Recently, I heard someone say that the lightning in early spring thunderstorms causes the grass to green up. After having a wave of thunderstorms move through our area in the last week and seeing the significant greening of the grass, I decided to investigate. It turns out that there does seem to be some science behind the idea.
If you think back to your middle school science lessons, you may recall that there is a process called the nitrogen cycle. Put simply, the nitrogen cycle shows that nitrogen is present in different forms based on where it is found. In the atmosphere nitrogen is in the form of N2 while in the soil we commonly think of nitrogen in the form of Nitrates or Nitrites (NO2 and NO3).
We may also recall from those long ago lessons that Earth’s atmosphere is 78% nitrogen and that the nitrogen (nitrates/nitrites) found in the soil help plants grow. In fact, many of us apply nitrogen-based fertilizers to our yards and gardens in order to give plants a boost.
Now, getting back to the concept that lightning in the spring thunderstorms will jump start our yards for the season. Although a large portion of our atmosphere is actually nitrogen, it is not beneficial to our plants whose roots grow down into the ground. In order for these plants to utilize the nitrogen available in the atmosphere, the nitrogen must undergo a change in the atmosphere and enter the soil. This is where the lightening comes in.
When lightning strikes, the rapid heating and cooling of the atmosphere in and around the lightning bolt causes the atmospheric Nitrogen or N2 to break apart into single nitrogen molecules which rapidly join with Oxygen molecules which forms Nitrogen Oxide or NO. These compounds quickly form bonds with additional oxygen molecules to form Nitrogen Dioxide or NO2. Nitrogen Dioxide quickly dissolves in water to create Nitric Acid. Since spring thunderstorms often bring torrential rains, nitric acid is formed quickly and is carried down to the earth in the raindrops. Thus, adding Nitrogen to the soil in a way that can be utilized by plants and other organisms.
It typically takes a few days for the plants to utilize this influx of nitrogen in the soil which means it generally takes a day or two for the grass to start showing the benefits of the extra nitrogen.
It has now been several days since the first thunderstorms of the season passed through our area and you may have noticed your grass looking greener this week. If so, you can thank last week’s thunderstorms for jump starting our lawns and moving us one step closer to yard work season.