The Pre-History of Soil Science: Jethro Tull, the Invention of the Seed Drill and the Foundations of Modern Agriculture.

Eighteenth-century British gentleman farmer Jethro Tull (1674-1741) is popularly regarded as the inventor of the seed drill, widely cited by agricultural historians, soil scientists and school history textbooks alike. Whether Tull was in fact the first to experiment with a mechanical seed drill and the horse-drawn cultivators drilling made possible is doubtful, but he did do much to make their acceptance in the long run more widespread. What is less well known is that Tull's mechanical innovations were accompanied by a theory of plant nutrition--and a social agenda--which were equally important to the adoption of the new machines. Although he came to celebrated by later generations, Tull's work attracted fierce critics in his own day and immediately after, not least because he categorically rejected the value of manures in maintaining soil fertility. Instead, he proposed a mechanistic theory of plant nutrition in which the stirring of the soil with the cultivator could substitute for the processes of decomposition thought to be contributed by manures, with less labor and expense. For Tull, the drill was part of an explicit strategy to minimize reliance on an unruly labor force. He also directly challenged the idea that Virgil and other classical authorities could be of any practical use in farm management. In other words, Tull was an anti-georgic improver, and could only be reinserted into the canon of agricultural history by glossing over the objectionable parts of his work. This paper will explore how, a century before Liebig, Tull's New Horse-Houghing Husbandry (1731 and later editions) sparked heated debates over a constellation of issues which are still with us today: no-till vs. tillage, net profits vs. gross yields, soil biology vs. soil chemistry, yield per acre vs. yield per unit of labor, rotation costs vs. input costs.