Salvail: Wonders of science feed growth underground

Nitrogen is the primary nutrient responsible for that deep green colour in foliage and for vigorous plant growth.

As the days lengthen and we enjoy the sunshine on our eager faces again, an amazing world of biology and chemistry is taking place outside. What is often overlooked and under-appreciated is the remarkable changes and processes that are occurring in the ground under our feet.

One of the first dramatic changes to the soil in spring comes from the snow itself. As snow forms it fixes nitrogen from the atmosphere and holds it in the snowpack all winter. When warmer temperatures arrive in spring, all that melting causes the nitrogen to leach into the soil profile. Nitrogen is the primary nutrient responsible for that deep green colour in foliage and for vigorous plant growth. Ever notice your lawn always seems greener after a good rain? It’s that fixed nitrogen from the atmosphere that does it! So imagine the potential nitrogen added to soil from months of snow that melts over a short period of time.

The melt also reveals the leaf and plant litter that was left over from the last growing season, now breaking down and softening as it decays. And a good thing it’s around because there are billions of microbes in the soil that are also waking up and they are hungry! Soil microbes feast on this litter, or detritus as it technically called, and turn it into an extremely valuable compound called humus.

Humus, sometimes called ‘black gold’, is tremendously valuable to plants, soil and the environment. It helps plants take up nutrients from the soil that would ordinarily be difficult for them to absorb. Humus helps the soil retain moisture and it darkens the soil, which increases the absorption of heat from the sun’s rays. Remarkably, humus also breaks down toxic and polluting compounds in the soil, literally cleaning up some of the contaminants we put in our environment!

With early spring soil now saturated with nitrogen, teeming with hungry microbes and possessing rich humus, it’s time to turn our attention to the plants themselves. Ever wonder just how plants even know it’s time to wake up? It turns out that there is a molecule in the plant’s root structure that tells it to grow and to flower. When the temperatures go down, this molecule stops being produced and the plant safely prepares itself for the long winter. But after 20 days of consistently frigid temperatures the molecule becomes active again, and for reasons not fully understood, tells the plant to spend the next 20 days slowly ‘waking up’. This, of course, is exactly when the soil is coming into its richest, most ideal conditions; it’s a beautiful relationship in nature that has developed and evolved over millions of years. As the plant begins to grow, it uses reserves in its roots to get started. Without the richness of these spring soil conditions, the plant would be under stress and be far more susceptible to pests and diseases.

So go outside and look at your tulips coming up, look at your trees that are budding out and appreciate how much happens underground to make it all happen. It may have taken you an afternoon to clean up the patio and put out the lawn furniture but it has taken months for the microbes, molecules, nitrogen, decomposition, humus, and spring warmth just to coax open a beautiful flower for us to enjoy. And it all happened right under your feet.