The first thing any soil student learns on the first day of class is to never, ever call it dirt.
“I drive that home by talking about the dust in the corner of your kitchen you have not gotten up,” Dr. Ivan Fernandez, professor of soil science at the University of Maine, said. “It does not have a lot of value, unless it’s to a rug mite.”
Soil, on the other hand, is so much more than what people walk on.
“The stuff covering our landscape is alive with physical and chemical processes and a lot of biology,” Fernandez said. “It produces our food, supports a vast biodiversity, stores carbon, stores and purifies water, we have found antibiotics in soil and we even get clay from soils.”
From the shallow, well-drained Lyman soil series dominating southern Maine to the excessively drained Thorndike series in central Maine to the moderately well-drained Perham soils to the north, there is a vast array of soil types — or series — in the state.
“The ‘series’ is a classification of soils like we have for animals and plants,” Fernandez said. “There are a total of 23,000 soil series in the country, 119 soil series are found in Maine, [and] 87 of those [that are] found in Maine were first identified and named in the state [and] that means that no matter where it is found in the country, it will have the name we gave it here in Maine”
There is even an official Maine soil — Chesuncook was named the state soil in 1999 and selected in part due to it being a widely distributed soil in Maine and the fact Henry David Thoreau writes about northern Maine’s Chesuncook Lake in his “The Maine Woods.”
The Chesuncook series is very deep, moderately well drained soils found on Maine’s till plains, hills, mountains and ridges and were formed by glacial till. As such, it was considered the most representative of the Maine soils.
Maine’s soils, according to Fernandez, were born of the last glacial age and are young, by geological standards.
“Our soils are naturally young because the glaciers covered the state up to 10,000 years ago,” he said. “So there is a lot of new raw [soil] material being formed here compared to tropical areas where the soil has been weathering for millions of years.”
Broadly speaking, Maine’s soils were directly deposited by the glaciers in the forms of clay, clay mixtures, silt, sand, gravel and boulders.
“Most of Maine’s forests are growing on till deposits that can be coarse loamy and yet quite productive,” Fernandez said. “Then you have special cases of that till — like in Aroostook County where the soil has more calcium carbonates in the rocks and that is part of why the county is known for agriculture because all that calcium is a good nutrient for plants.”
Heading toward the coast and Down East, the glacial deposits were often washed by the melting ice, removing fine materials such as silt and clay, leaving behind the area’s sandy blueberry barrons and eskers.
Farther south along the coast, according to Fernandez, the sticky clay and silt settled out, leaving tidal mudflats.
Maine also has areas of pure organic soils such as peat bogs, in which all the soil layers are formed from organic materials, not rocks and minerals.
Knowing your soil is to love it
“Of course people should know their soils,” Fernandez said. “If you know you are dealing with sandy or clay or poorly drained soil it will tell you how to manage that soil [and] if you know some of the characteristics of the soil you are dealing with there are other people who have a lot of great advice on how to make your soil work for you to meet your goals.”
For the computer and Internet savvy, there is also a wealth of soil information available through the USDA’s online resource Web Soil Survey, Fernandez said.
For Maine’s gardeners and homesteads, knowing their soil is key, according to Eric Sideman, crop specialist with the Maine Organic Farmers and Gardeners Association.
And the best way to improve the soil?
“Organic matter,” Sideman said. “There are basically two kinds of soils you will be working with — sandy soils that don’t hold water or nutrients, or clay that does not drain [and] organic matter helps with both.”
Organic matter — such as compost or manure fertilizer — will help stabilize the sandy soil and allow it to hold more moisture and nutrients, Sidemand said.
By adding fresh organic materials to clay-like soil, as the organics decompose they release a substance that causes the tiny particles of clay to adhere to each other and harden, creating spaces for water to drain out.
Planting a cover crop like oats over a planned garden site is also helpful, Sideman said.
“It’s one of the easiest ways to add organic matter,” he said. “Don’t let the oats get too tall and then till them in to the soil [and] you can replant in the fall and let the winter frost kill the oats off and just till them in in the spring.”
Buckwheat is another excellent cover. Sidemand said, as it shades the soil and prevents weeds from taking root and growing.
“It’s a slow process,” Sideman said. “You want to plan at least a year out for the soil to be ready for planting.”
More than crops
Soil, Fernandez said, does so much more than provide food.
“It stores carbon and that is so important with regards to climate change,” he said. “If we do things that add carbon to the soil by adding manures and sustainable cropping and sustainable forestry, the soil has a tremendous capacity to increase its carbon content [and] that is a way to address greenhouse emissions as we deal with climate change.”
Generally, Maine is doing a good job taking care if its soil, Fernandez said.
“We are working on reducing erosion and the strong organic [farming] movement bodes well for those cultivated soils,” he said. “Ninety percent of the state is forested and [forests] are the most secure way to preserve soils and prevent erosion.”
The key is continued care, Fernandez said.
“We have not abused most of our soils,” he said. “But it won’t take much to degrade it if we stop paying attention to it and that will cost us all.”
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