Jethro Tull’s name appears in almost every History text book as a figure of heroic stature in the agrarian revolution which allegedly transformed British Farming in the 18th Century.
Recently lionised on TV and in a colour supplement as a hero in the history of farming Wikipedia tells us “he is considered to be one of the early proponents of a scientific (and especially empirical) approach to agriculture.” So how true is this verdict?
1.] Tull states that the key food for plants is “earth” and dismisses “nitre” as plant food. Essentially he argues that it is fragments of powdered rock that are taken in by tiny mouths on the roots of crops, and that there must be a repeated stirring up of the soil to stimulate this process. But moisture and humus in the soil as well as micro-organisms and nitrates, phosphates and trace elements are vital for growth, and incessant disturbance at the roots of growing crops can be harmful.
2.] Tull dismisses manuring and crop rotation as not only unnecessary but bad for the soil – but they are beneficial if correctly used. Growing the same crop every year without replacing nutrients impoverishes the soil.
3.] Tull’s seed drill was not the first invented, nor was it particularly effective and could only operate if made to a very precise standard by a cabinet maker. Only after his death when gearing was added was it effective. Even so a skilled team of workers broadcasting could be more effective than early mechanical devices, in sowing grain crops.
4.] Tull’s sowing rate for grain led to a very low density with wide spaces between the rows to allow the horse hoe to hoe between, not primarily to remove weeds but to till the soil and stimulate the roots.
5.] Tull claimed good results empirically with his methods but I am sceptical and in the long term his methods would exhaust the soil and yields would fall and the soil erode. His results may have looked good in terms of ratio between seed sown and yield, but between farmed area and yield they cannot be as good. Is there any evidence of subsequent widespread use of his methods?
6.] The heroic verdict on Tull fits the popular myth that there is an inevitable tide of human progress which is the product of an elite group of ‘scientific men of genius’ [hardly any women]. Numerous earlier changes in farming, earlier knowledge and the roles of market demand and more efficient arable units are far more significant in the development of agriculture than heroic individuals.
For changes in agriculture see Chapters 1 and 2 in Kimble’s Journey