By James DeDecker
As Michigan farmers look to the New Year and growing season ahead, recent snows encourage optimism. In northern climates, snow can account for a significant portion of annual precipitation, increasing soil moisture essential for plant growth. Beyond this clear advantage, snow positively impacts other aspects of agriculture from soil fertility to global trade.
Michigan receives average annual snowfall totals ranging from 30 inches in the southeast to as much as 200 inches in parts of the Upper Peninsula. This may seem like quite a bit, but it takes about 10 inches of snow to provide 1 inch of water. Annual precipitation totals vary much less across the state ranging between 30 and 38 inches on average. Therefore, snow accumulation provides between 7% and 66% of total annual precipitation. With nearly half of the state still facing abnormally dry conditions, the value of this winter precipitation is magnified. A few more significant snow events could put the drought of 2012 officially behind us.
However, growers need not wait until a spring thaw to realize the benefits of snow. In its frozen physical state, snow provides value beyond the water it contains. For example, air caught within accumulating snow acts as insulation for the soil ecosystem. Two to 4 inches of snow can raise the soil's surface temperature 30 to 35 degrees Fahrenheit. Many overwintered crops are dependent on this insulation factor. Wheat requires at least 3 inches of cover to avoid significant winterkill in cold climates; 4 to 6 inches provide additional protection.
Some livestock systems benefit from snow as well. Healthy cattle can ingest much of their water requirement as snow when grazed on winter pasture. Grazing snow is a learned behavior, and Michigan State University Extension recommends that cattle be observed closely as they adjust. Snow must be abundant, and not compacted or icy. Still, the right kind of snow may allow cattleman to extend the grazing season on stockpiled forage or crop residues without a winterized watering system.
Snow can also contribute to soil fertility. Snowflakes trap dissolved organic nitrogen, nitrate and ammonium in the atmosphere, delivering it free-of-charge to cold and quiet fields. Rain and snow together provide between 2 and 22 lbs of nitrogen per acre each year. Even the wildest winter storm would not be cause to cancel your fertilizer order, but could be worth as much as $18 per acre in urea equivalency.
Far downstream from the farm, snow keeps the gears of agricultural trade turning. Channel depths on the Mississippi River fell dramatically during the drought. The Army Corps of Engineers is removing rock pinnacles from the river bottom, and shippers worry that the Coast Guard will soon tighten restrictions on barge traffic. Recent snows and dam adjustments on the Missouri River may temporarily halt the decline.
DeDecker writes for Michigan State University Extension