Soil Health

Debby Luquette
Adams County Master Gardener

(2/29) When the winter months offer more time for reading than engaging outdoor activity, it is a period of relative leisure for gardeners. I recently finished Founding Gardeners, The Revolutionary Generation, Nature, and the Shaping of the American Nation, by Andrea Wulf. I’m writing this on Washington’s Birthday, in the month we celebrate President’s Day. It’s a time in which we remember many aspects of our history and the people that built America. In fact, this is a very fertile topic, since our Founding Fathers were also our Founding Gardeners. On Washington’s, Jefferson’s and Madison’s estates, gardens took on a special significance. These estates, by necessity, had kitchen gardens for food to feed their households and guests, as well as formal gardens for personal enjoyment and to impress visitors. They also provided a special place to escape the burdens of their public lives and engage in botanical experimentation. As gardeners, these three statesmen, along with their northern compatriot, John Adams, were also interested in soil health.

George Washington, one of the first champions of native flora, used Mount Vernon to showcase his interest. His formal garden followed the general format commonly found on the English country estates, but he wanted his plantings to demonstrate to visitors what he saw as the strength of America. Perhaps it was because he was one of the few early statesmen to venture past the Appalachians that Washington admired the trees of American forests. They reflected for him the strength, stature and resiliency of the American colonists. He designed Mount Vernon’s gardens to be a showcase of the most beautiful of America’s trees, straying from the stylish plantings in European formal gardens.

Washington was also interested in improving America’s poor agricultural habits, which even then, tended to deplete soil health. Soil health was his key to agricultural success. There was little time for Washington to enjoy the work as a farmer at Mount Vernon, but when the occasion arose during his public tenure, he rode the countryside talking to farmers. His correspondence with his estate managers, having employed a few during the years which absented him from his estate, reveals interest in his harvests and instructions on plantings. He desired to engage an estate manager who shared his interests and could oversee various experiments in rebuilding soil health besides maintaining the gardens.

Even with the demands of camp life during the war, and later, the hectic political scene of the infant United States, Washington’s correspondence with his manager focused on his plantings and the ideas he wished to try on his return. Rebuilding soil fertility was a focus for his efforts. Having read the current agricultural science literature sent from England and from conversations with farmers he met in his travels, he instructed his estate manager to experiment with various materials, including gypsum, marl, various manures, and even material from a small scale dredging of the Potomac River.

Soil Health? I’m sure you understand the use of manure. Marl, a siltstone fairly high in calcium and iron, with lesser amounts of potassium, magnesium and phosphorous, was ground and used where it was available in the Middle Atlantic region. Gypsum, composed primarily of calcium sulfate, was also a widely used fertilizer in Early American history.

In Preindustrial America, dredged material from waterways of the Middle Atlantic was high is silt eroded from the hillsides due to poor farming practices in the Piedmont areas. Much of early America’s best farmland lay at the bottom of the Potomac, Susquehanna and other rivers draining into the Chesapeake Bay. Recovering this soil would make sense if it could be practically managed in those days before mechanization.

And manure — full of organic matter, high in nitrogen and all those good things to put in a garden! That makes sense to us without needing to resort to references to find out what Early American farmers knew. What they didn’t know, and science has since unraveled, is how the manure feeds the soil. Those early farmers hadn’t yet made the connection that organic nutrients feed soil microorganisms.

Today we understand that soil is inhabited by billions of bacteria taking up nutrients to live, and as part of their life, they secrete an organic ‘glue’ that holds the soil together in clumps, or aggregates. These bacteria are food for other microscopic organisms, like amoebae, and barely visible nematodes. Aren’t nematodes bad? Only a few, and these bad actors are food for good nematodes.

Along with these soil creatures are the fungi, which interact directly with plants. Most soil fungi spend their lives in a vegetative form that we don’t usually see or recognize; we know these guys when we see them in their reproductive phase as mushrooms or cup fungi. Most of their lives are spent as long filaments traversing the soil, and often wrapping themselves around plants’ rootlets. Here they set up a useful relationship with the plants, exchanging soil minerals they’ve absorbed for the plants’ sugars. Plants can photosynthesize, but usually don’t have access to as much mineral nutrition as they can use. Fungi, on the other hand, need more sugar than they can find in the soil and are willing to exchange the minerals they’ve absorbed for sugars. They form a symbiotic relationship, a win-win for both.

There is one farming activity the early Americans engaged in that we are beginning to realize isn’t the best thing for soil, and that is frequent tilling. They tilled less than we do today, of course, since cultivating by hand or hitching the horse to the plow was more difficult than starting the rototiller. They also tended to have larger gardens, even kitchen gardens, than we do today. Tilling and cultivating the soil breaks up the soil aggregates and fungal threads (hyphae), making a plant’s life more difficult. Disrupting the soil ecosystem — the interaction between the soil minerals, soil microorganisms and the plants’ roots — makes life considerably more difficult for the plants. And it leads to soil that is more easily eroded.

Sometimes gardening can make interesting connections. Founding Gardeners strengthened my connection to the early days of our nation. These men viewed plants and gardens as symbols of America’s greatness and food for the table. Interestingly, when political disagreements broke out during those meetings concerning independence from England — and apparently they got pretty ugly — these men visited gardens together to settle their minds and souls.

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