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Mount Vernon staff roll up their sleeves to test different soil mixtures—just as Washington did in 1760.

George Washington often used experimental methods to advance agriculture at his Mount Vernon estate. Realizing that cultivating tobacco depleted his soil, Washington switched to growing grains, namely wheat, oats, and barley. Always seeking better results in his harvest, in 1760, he conducted an experiment to discover the best fertilizer mix for these grains.

After reading journal entries about this experiment, Mount Vernon’s Historic Trades staff re-created the test at the Pioneer Farm using the same mixtures: cow manure, horse manure, sheep manure, creek mud, and river sand dredged from the Potomac River. The staff followed the instructions in Washington’s diary entry from April 14, 1760:

“All mixd with the same quantity & sort of Earth in the most effectual manner by reducing the whole to a tolerable degree of fineness & jubling them well together in a Cloth. In each of these divisions were planted three Grains of Wheat 3 of Oats & as many of Barley, all at equal distances in Rows & of equal depth (done by a Machine made for the purpose).”

Director of Horticulture Dean Norton (left) and Historic Trades Manager Sam Murphy sit patiently by as their soil experiment unfolds.
Director of Horticulture Dean Norton (left) and Historic Trades Manager Sam Murphy sit patiently by as their soil experiment unfolds.

Between July 7 and September 4, staff monitored the progress and shared details about the experiment with interested guests. Visitors could play in the dirt and plant seeds in a soil box like Washington, learning about the experiment and Washington’s agricultural prowess. Guests could also follow the experiment on social media and vote on the Mount Vernon website for which combination of grain and soil they thought would be most successful. At the conclusion of the experiment, Historic Trades Manager Sam Murphy and Director of Horticulture Dean Norton determined that sheep manure produced the best results for growing wheat and barley, whereas horse manure proved the most successful for growing oats. They also noted differences between Washington’s experiment and theirs—specifically the later start date and the fineness of the soil—that may have played a role in the outcome.

“Regardless of the differences, most importantly, Washington loved these experiments. He wanted to learn as much as he could,” said Norton.

“I was firmly convinced river sand would yield no results, and sheep manure would yield the best, since [Washington] had sheep everywhere,” said Murphy. “That we had growth in all five boxes and we’ve had a lot of people following this, it’s a success.”

Read about Washington's innovative dung repository

Washington the Farmer

Washington studied and implemented improved farming methods throughout his life. In fact, he thought of himself first as a farmer.

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