Here’s a new issue for us to ponder in our quest for improved sustainability and environmentally-sound gardening and farming practices. It was recently reported by NOAA scientists that nitrous oxide has become the largest ozone-depleting substance emitted by human activities. Yes, nitrous oxide causes destruction of the ozone layer.

Nitrous oxide is emitted from natural sources, such as cow manure, as well as from sewage treatment and some industrial processes. So where is the connection to gardening and farming?

Well, nitrous oxide is a by-product of soil fertilization, specifically nitrogen. Bacteria in the soil and in the oceans break down nitrogen-containing compounds and release nitrous oxide. Nitrous oxide breaks down when it reaches the stratosphere to form nitrogen oxides that trigger ozone-destroying compounds.

As gardeners we have control over this process by limiting the amount of nitrogen fertilizers we use. For example, instead of fertilizing the lawn four times a year (which is simply overkill) apply a good slow-release winter fertilizer in September and maybe do a light fertilizing in early spring. The best way to check the amount of nitrogen in your soil is to do a soil test every three years … and then fertilize accordingly. We CAN protect the ozone layer, so let’s do it.