Precipitation proves precious for plants preparing for spring

Mother Nature must have stumbled and bumped her head earlier this week. In our neck of the woods, the precipitation in a 24-hour period ranged from a gentle spring shower to a driving rain to a pleasant snowfall with swirls of flakes that measured up to 2 inches across.

Nature’s indecision – is it spring or winter? – is both the source of frustration and good news for the gardener. Although the level of satisfaction gained from viewing newly tilled garden is seriously diminished when a thick layer of snow has blanketed its pristine surface, we may think of springtime precipitation as a time-released, nutrient-saturated gift of much-needed moisture.

Our forebears called spring snowfalls such as these “poor man’s fertilizer.” Even those unable to describe the phenomenon in scientific terminology undoubtedly recognized that grasses looked greener after a spring rain or snow shower. Today we are able to define the greening of fields after a weather event in spring in scientific terms.

As gardeners, we think of the soil as the dominant source of our plant nutrients, and of course, rich soil is the most direct source of nutrition for our garden crops. The soil contains an abundance of some of the nutrients our plants require for growth. Carbon, nitrogen, hydrogen, oxygen, phosphorus, potassium, sulfur, calcium, iron and magnesium are essential nutrients. Some nutrients are derived from the minerals in soil, others from amendments we add to the soil and still others from the atmosphere.

In fact, a significant source of nutrients become available to our plants through rain and snowfall passing down to the soil from the air above us. Nutrients that enter the soil captured by rain and snow technically are called “wetfall.” Others are made useful to plants through “dryfall,” particles that settle on the ground during periods of no precipitation.

Rainwater and snowfall may contain solutions of trace chemical elements (read: garden nutrients) from the atmosphere that are derived from gases in the air. Nitrogen and sulfur are found in abundance in the atmosphere. Elements such as sodium, magnesium and chloride from evaporated ocean water also may contribute to the trace solution of elements in wetfall. Dryfall,

rich in calcium, potassium and

sulfate, may arise from dust

particles that result from

wildfires, volcanoes and windstorms.

Some particles and gases are “washed” from the atmosphere during a rain shower. At other times, particles and gases form the nucleus around which a rain droplet forms.

All things considered, nutrient concentrations are greater during a rainfall than in a snow shower, and droplets of fog are even more highly concentrated. The nutrient concentrations are greatest during the early part of a rainstorm. They reduce as the atmosphere is cleansed of elements over the course of the rainfall.

Many of the nutrients gleaned from the atmosphere enter the soil and are taken up by plants through their roots. Some elements, however, are absorbed through the leaves of plants.

Perhaps, then, there is a silver lining to these rather frustrating spring snowfalls. If we can’t be comforted with the thought that our hands soon will work the ground, perhaps we’ll find solace in knowing that the snow showers this week are feeding the soil from which our plants will shortly abound.

Diana George Chapin is the NEWS garden columnist. Send horticulture questions to Gardening Questions, RR1, Box 2120, Montville 04941, or e-mail them to dianagc@midcoast.com. Selected questions will be answered in future columns. Include name, address and telephone number.