The Great Black Swamp was born out of winter


Our landscape is covered with snow, and the weather is frigid and cold. Did you ever wonder how winter helps our soil?

In Northwest Ohio we are influenced by the Wisconsin Age glacier that slowly retreated approximately 10,000 to 20,000 years ago. This glacier was estimated to be 5 miles high of ice and rock that flattened our landscape. As it retreated, it left behind limestone as our underlying bedrock and soils consisting of clay with pockets of sand deposits, which was known as the Great Black Swamp. The swampy conditions allowed for the establishment of native prairie grasses and forested areas. When European settlers drained the swamp and converted the ground to agriculture the soil gained rich organic matter.

Fast forward to 2023. With the growth of urban centers, infrastructure such as roads and railways, as well as industrialized agriculture, our soil has lost some of this rich organic matter. Organic matter is what adds structure to our sand and clay. Structure is what opens the soil allowing for better oxygen and carbon dioxide exchange in the soil, as well as drainage for roots of plants to grow and thrive.

Organic matter is not the only component that makes this all work. Structure is also created during the winter in Northwest Ohio.

To understand this phenomenon, we need to examine clay particles. Clay particles are very tiny, very sticky, and are flat dinner-plate shaped. Clay particles easily stick to each other and because of their dinner plate like appearance water drains through the soil slowly. If you stack flat dinner plates in a sink and fill the sink with water and pull the drain plug, water will drain slowly in the sink as well.

During the growing season, unless it is extremely wet like back in 2019, plants during their respiration process pull moisture from the soil. Also, evaporation from the sun pulls moisture from the soil as well; however, during late autumn plants are going dormant and the sun’s energy is decreasing. Late autumn and early winter rains soak up the soil again. Snow comes, melts, and snow comes again. The soil becomes more saturated. Winter has a firm grip on Northwest Ohio.

The ground freezes. The water freezes in the soil and expands breaking the grip of the dinner plate appearance and creating small clods called peds in the soil. These peds become jagged in appearance and allow excess moisture to drain through the soil. The freezing and thawing of the soil all through the winter increases the amounts of these peds . As the peds increase in the soil, roots have better oxygen and carbon dioxide exchange in the soil, creating healthier root systems.

As spring approaches, bacteria and other fauna wake up in the soil and resume their functions benefitting as well from the peds created during the winter. Unfortunately, we humans have a way to destroy in an instant what nature created over several months.

The biggest culprit is lawn rollers. Lawn rollers compact the soil breaking apart all the naturally occurring peds thereby decreasing the pore space that roots need to thrive. Other culprits include any type of heavy equipment across the ground during the spring and summer.

Did you know wintertime activities can also break apart these peds? Nick Eckel, Ohio State University Wood County agricultural educator, states what most of us do not take into consideration when it comes to snowmobiles and ATVs: Was the ground frozen before we received snow? Frozen ground protects perennials, strawberries and wheat crops holding the crowns and roots in place protecting the plants.

Unfrozen ground, on the other hand, opens the door to damage. When we receive snow cover it insulates the soil underneath keeping it in an unfrozen state. Not only do snowmobiles and ATVs potentially cause crop damage, but they also can compact the soil destroying the peds.

Though we often think of winter as the quiet dormant season of the year in our landscape, it is not. Winter is an amazing time for our soil as it repairs and prepares for the growing season to come.

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