Environmental Engineering Reference
In-Depth Information
6.5 Two inventions that made large-scale grain cropping
possible. (a) Steel riding plow. (b) Harvester. Reproduced from
Ardrey (1894).
production of between 65 kg (India) and 1560 kg (U.S.)
of grain, or roughly 1-25 GJ. In edible terms, this equals
(with at least 10% milling rate) 0.9-22.5 GJ of food en-
ergy. The maximum was enough to support about six
people on typical preindustrial grain-dominated diets,
but the large, well-fed horses requiring so much feed
were working at a rate at least tenfold higher (750-850
W) than an average human. Even when considering the
necessity to feed the nonworking horses (about one-third
of the total stock), the difference would scale to more
than sixfold. Even a horse's claiming land capable of pro-
ducing food for six adults made energetic sense. More-
over, heavy horses were able to provide traction for tasks
that were both energetically and logistically beyond the
practical means of human labor, tasks ranging from deep
plowing of clay soil to pulling wheat combines, breaking
up large expanses of natural grass lands, and performing
critical tasks in a timely and efficient manner.
Animals harnessed to better implements and to new
harvesting machines made it possible to cultivate grain
fields on unprecedented scales, at the same time sharply
reducing the demand for human labor (fig. 6.5). The
nineteenth-century achievements of the United States
are certainly the best example of this combined effect
(Ardrey 1894; Rogin 1931). Charles Neubold's cast
iron plow of 1797 was improved by Jethro Wood's inter-
changeable moldboard, patented in 1819, and super-
seded by steel walking plows first made by John Lane
in 1833. The production was commercialized by John
Deere in the 1840s and improved again by Lane with
the introduction of a three-layer soft-center steel plow in
1868. Two- and three-wheel riding plows followed after
1864, and gang plows, with up to ten blades, drawn by
12 horses, were used by the late 1800s.
The first mechanical grain reapers were patented in
England between 1799 and 1822, and two U.S. inven-
