Snow: Poor Man's Fertilizer

Snow and other forms of precipitation contain nutrients such as nitrogen and sulfur. If the ground isn’t frozen or saturated, these nutrients can be absorbed into the soil. In addition, snow provides an insulating blanket over the ground that helps to protect delicate plants from severe cold and winter winds.

By Jennie Shurtleff

Perhaps you've heard the expression in which snow is referred to as "poor man's fertilizer." It turns out that this is more than just an "old wives' tale." Snow can actually add nutrients, most notably nitrogen, into the soil. In an article entitled "Poor Man's Fertilizer," naturalist and Woodstock resident Tim Traver explains how this happens.

Tim notes that while there is lots of nitrogen in the air, it cannot be used by most plants until it has become "fixed" by bonding with other types of molecules, such as oxygen or hydrogen and ammonium. In nature, there are several ways that this "fixing," or changing nitrogen into a useable form, occurs. One way is through a type of symbiotic nitrogren-fixing bacteria found in the root nodules of various legumes, including beans, peas, clover, and alfalfa. Another way is through precipitation. The air is filled with nitrogen gas. When lightening occurs, the energy in the lightening "fixes" the nitrogen by enabling it to react and bond with other molecules in the air. When precipitation - such as rain or snow - falls through the air, it can pick up these nitrogen compounds which are then released into the soil. Nitrogen is also picked up in the atmosphere by dust particles that settle on the earth thereby returning the nitrogen to the soil. Some agricultural studies estimate that, in the United States, between 2 to 12 pounds of nitrogen, per acre, are returned to the soil each year.

Once fixed nitrogen is in the soil, it can readily be absorbed by plants and, in turn, by other organisms. While nitrogen is often maligned because too much nitrogen can have harmful effects on plants and the environment, in appropriate quantities and when added so that it doesn't evaporate or wash off fields, it can increase production dramatically. Tim Traver notes that the invention of synthetic nitrogen fertilizer in the early twentieth century boosted crop yields "to previously unimaginable levels. Corn yields jumped from 22 bushels/acre in 1930 to 80 bushels/acre by 1968 in the United States. This exponential increase in food supply helped the human population to grow from 1.5 billion people in 1900 to 6 billion in the year 2000."

While it is unlikely that most of our forbears understood the science behind the nitrogen cycle, they were keen observers of nature, and clearly could see that their crops often did better after a snow or rain storm.