The American Meteorological Society defines “spring snow” as being coarse, granular, wet snow, resembling finely chopped melted ice. Foresters worry that this kind of snow can seriously harm trees. When such heavy snow piles up on branches, the stress can be too much, resulting in fractures. Such breaks are most common in March and April.
Tree experts can determine the point at which snow becomes dangerous by analyzing clusters of falling flakes. When the snow clusters are about the diameter of a quarter, trees’ safety is being threatened.
In this case, the snowflake’s physical condition is the trait of wet snow: a lot of water is being held, making the snowflake cluster sticky. Rather than falling through the tree branches like drier, smaller flakes, such wet snow adheres to them, piling up in thick, heavy layers. Wet snow falling on tall, sturdy trees can break branches. But the problem is worse on young trees with lanky branches and small crowns. Those are either broken by snow loads or bent over so far that they never right themselves entirely. Much smaller trees, including saplings, are usually limber enough to rebound.
On Feb. 19, the weather forecast called for freezing rain and/or wet snow. That night we got about six inches of the latter – a mere pittance compared to regions farther north. No branches were broken on any of our trees, but the snow made for difficult blowing with our 16-year-old machine. Snow removal was particularly challenging where the oversized snowflakes landed on puddles in our driveway, rapidly forming slush. Several times I had to shut off the impeller to claw out impacted slush. All this extra moisture apparently shorted out the spark plug too.
I had to drag the stalled machine to our garage, where a plummeting mercury transformed the slush into rock-hard grey frozen water. The temperature on Feb. 24 was in the 40s, and combined with hot water from the kitchen sink, it dispatched the once-frozen slush to the garage’s concrete floor. My faithful machine returned to active duty.
Although some refer to this form of precipitation as “heart attack snow,” many so-called old-timers refer to this spring snow as “poor man’s fertilizer.” This is because snow, like its liquid cousin rain, contains nitrogen (N) as well as minute but measurable levels of phosphorus (P) and sulfur (S).
Wetter snow – caused by drier flakes melting just a little and sticking together – wash these elements out of the atmosphere, depositing them on our fields, gardens, yards and trees. The airborne presence of these minerals has been increased by byproducts of industrialization (emissions). But they still are plant nutrients, donated at no charge to crop growers.
The amount of S in the atmosphere has decreased in recent years, largely due to the 1973 Federal Clean Air Act. Our atmosphere is approximately 78% N, but most of that N is rather insoluble in the couplet (N2) form. Pollutants, like the greenhouse gas nitrous oxide, merge much more readily with snow (and even raindrops) than does S.
The amount of N believed by scientists to merge with precipitation annually ranges from 2 to 12 lbs./acre; an average value of 7 lbs. is commonly presumed in soil nutrient calculations. Meteorologists believe that snowflakes, due to their crystalline nature, pick up more N than raindrops do.
How much N we get from snowfall depends on location and annual snow accumulation, particularly the spring kind. An average annual N deposit of 7 lbs. – compliments of Mother Nature – seems small compared to typical commercial N applications for corn exceeding 100 lbs., but it’s free. It’s a nice benefit, assuming we don’t lose too many tree branches.
While rain and lightning also deliver N, snow boasts several agronomic advantages over the other two sources. First, snow stays around for a while, releasing its nutrient package slowly. Snow also helps insulate plants from temperature fluctuations, which can cause heaving and related problems associated with freezing and thawing. Third, snow makes small plants, like strawberries, less visible to hungry critters. Snow helps prevent plant growth from starting too early.
Lastly, snow, unlike heavy rainfall, doesn’t leach nutrients away from plant roots. In Nova Scotia, locals categorize spring snowfall into three categories: “robins’ snow,” which occurs just as the robins migrate back; “smelt snow,” which happens when the smelt are “running” in the coastal rivers; and “poor man’s fertilizer,” delivered by snow landing on freshly plowed fields in early spring.
Now let’s place economic benefit on free snow-borne N. I monitor closely the Argus North America Newsletter, a fertilizer industry periodical published twice monthly. From Argus, recent average quotes for urea (45% N) and ammonium nitrate (33.5% N) were $455/short ton and $323/short ton, respectively. This means that 1 lb. of N in urea costs $0.506, and 1 lb. of N in ammonium nitrate costs $0.482. These commodity prices are a little higher than they were a year ago, but they’re much lower than they were four years ago during the early stages of the COVID pandemic. So the average of 7 lbs. of snow-borne N replaces $3.54 worth of urea or $3.37 worth of ammonium nitrate. Cutting back 7 lbs. of either form of N looks like a pretty good idea.
Regarding weather orneriness – i.e., spring or late winter snow: About 35 months ago I wrote about Mother Nature’s white bounty. Less than a week after that, bounty turned into headache, as wet snow disasters blanketed the Northeast with widespread power failures. Hundreds of power line service vehicles swarmed into our part of Central New York, many of them from Midwestern states – visiting Indiana license plates were common. We were without power for four days and three nights. During daytime, we kept our house warm with a kerosene heater; at night, we just put on more blankets with our Boston terrier Sophie, who normally sleeps with us.
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