On the thin topsoil that overlay the clay slopes at Mount Vernon, George Washington grew wheat that sold in Alexandria, made ship's biscuit that was famous the world over--and rye that supplied his less celebrated distillery. The increasing number of cattle accounted for the introduction of mangel-wurzels, turnips, and other root crops in the rotation. The soil-building virtues of peas were discovered. Beef cattle grew in increasing numbers, and began to appear prominently in inventories and wills. Orchards and vineyards were planted more widely. With these developments, simultaneously with the decline of the tobacco trade, a lively business sprang up in shipping corn, wheat, and livestock to the West Indies....[25] In his efforts to develop methods of husbandry which would restore the fertility of the land, Washington reflected a concern which was widespread among Virginians of his time and the first half of the nineteenth century. Organized efforts to promote better husbandry through exchange of practical experience and dissemination of the results of experimentation and invention began in the 1770's.[26] Between 1790 and 1830, hundreds of publications on agriculture were produced[27] and more than 100 inventions of agricultural devices were patented to Virginians, among them Cyrus McCormick's reaper, the most influential mechanical factor in the development of American agriculture in the nineteenth century.[28] National leaders such as Thomas Jefferson, James Monroe, and John Marshall actively worked in societies which encouraged experimentation and study for improvement of agriculture through what was called "scientific farming." With the effort to establish scientific farming came experiments in crop rotation, with use of clovers and grasses interspersed between other crops, increased use of manure and artificial fertilizers, better plows and methods of soil preparation, and more attention to control of erosion. Interest in improving farm animals during this period led to introduction of merino sheep and new breeds of mules. Despite this active element in Virginia's agricultural system, and notwithstanding the substantial amount of intelligent and successful experimentation and publicity of results which this element inspired, many farmers in Virginia persisted in traditional ways. "Book farming," as the new methods were called, was decried in favor of the familiar ways of cultivating which were passed from father to son. This skepticism was strengthened, also, when experiments failed--as they did in many cases--and when Virginia agriculture suffered from economic depression along with the rest of the nation--as it did in the years following the War of 1812.[29]