The development of David Ricardo’s economic theory of distribution - the laws that determine the share of output between the economic classes - depended on specific connections at several levels between two practical sciences of the early 19th century, namely experimental agriculture and political economy. This paper shows how Ricardo, one of the foremost British economists of his day, combined his empirical knowledge of farming and agricultural experiments to develop both the content and method of Classical economics. The method of argument he developed depended upon numerical experiments that mirrored, in form and experience, the experimental accounts from agricultural science. The content of his arguments, and his derivation of the laws of distribution, depended critically on the effect of increased labour input into agriculture. This apparently hypothetical case was in fact a real question of political economy addressed by farming experiments within the context of the contemporary “spadehusbandry” debate.