In addition to his reliance on lots of manure, Jefferson improved his soil with cover crops and crop rotation. According to the Duc de la Rochefoucauld-Liancourt in his Travels through the United States of North America, in the Years 1795, 1796, 1797, Jefferson didn't allow his fields to lie fallow because he believed that "the heat of the sun destroys or at least dries up in great measure, the nutricious [sic] juices of the earth." While this may not exactly be the case, he was on to something, as cover crops do increase soil fertility, add organic matter, suppress weeds, and prevent erosion. At the JDG, we will be growing several cover crops used by Jefferson: red clover, buckwheat, and cowpeas (check back for plant profiles soon).
Buckwheat (Fagopyrum esculentum), from La flore et la pomone francaises, by Jean Henri Jaume Saint-Hilaire (1828-33). Missouri Botanical Garden. http://wwwillustratedgarden.org
Jefferson also practiced crop rotation, discussing the matter frequently with his son-in-law, Thomas Mann Randolph, and also with fellow gentleman farmer, George Washington. Writing to Washington in 1794, Jefferson laid out this six-year crop rotation plan: "first year, wheat; second, corn, potatoes, peas; third, rye or wheat, according to circumstances; fourth & fifth, clover where the fields will bring it, and buckwheat dressings where they will not; sixth, folding, and buckwheat dressings."
Crop rotation benefits both home gardens and field crops because it reduces nutrient depletion in the soil, as well as the build up of pests and diseases. As can be seen in Jefferson's plan, cover crops also play an important role in crop rotation. We look forward to reaping the benefits of both of these important planting practices at the JDG.
- Jefferson, Thomas. Thomas Jefferson's Garden Book. Edited by Edwin Morris Betts. Charlottesville: Thomas Jefferson Memorial Foundation, 1999.