From William Stanton
You edited my letter on food and fuel (31 May, p 23), perhaps thinking that my statement “A farmer using liquid fuels is at least forty times as productive…” must be exaggerated. Let me expand.
Before about 1750, when the Industrial Revolution began, farmers depended on human and animal muscle. Now, in all but backward societies, diesel-powered tractors and mains electricity have taken over. The increase in efficiency, thanks to fossil fuels, is colossal.
Over the hedge from my garden is a hay meadow 7 acres (2.8 hectares) in area. Mowing it by tractor takes about 1.5 hours. This compares to the full day, including breaks for food and cider, that a man with a scythe traditionally took to cut 1 acre. The tractor is roughly 40 times as efficient in terms of man-hours.
The next two procedures in modern haymaking, tedding the cut grass to dry it, and then baling it, each take the tractor about 1.5 hours. Before 1750 the farm workers, men and women, used rakes to aerate and dry the hay, then loaded it into carts with pitchforks. Again the efficiency ratio is something like 40:1.
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A giant combine harvester with its satellite tractors and trailers may be 100 times as effective as the peasants with their sickles, flails and threshing floors in recovering the grain from large acreages of cereals.
Medieval woodcutters harvested energy with sharp axes. Several of them would have taken a day to load their cart with logs and haul it from the forest to the village. Thanks to my chainsaw I can fill my car with logs cut to size and bring them home, a mile from the wood, in two hours.
Only 60 years ago, before piped water reached the streamless limestone plateau of the Mendip Hills, my neighbour’s cattle were supplied in summer by a horse and cart that carried a few large churns of water up the hill from the farm to a tank on the plateau 150 metres higher. The horse and driver managed 2 journeys a day to water the little herd of about 10 animals. Now there is no limit to the number of cattle that can be watered.
Picture the dairymaid on her three-legged stool, milking about five cows every hour by hand a century ago. Now, only the capacity of the milking parlour limits the size of the herd, sometimes as many as 400, that can be processed in two or three hours.
Whether it be ploughing the fields, hedging and ditching, clearing out ponds, or raising livestock, few modern agricultural procedures are less than 40 times as productive as they were when the work was done by humans, with or without farm animals.
The significance of this “40 Factor” cannot be exaggerated. How long do we have before fossil fuels are so scarce that global food production begins its shrinkage to about one-fortieth of present capacity?
The editor writes:
• Checking the factor of 40 simply produced too many complex and competing answers.
Wells, Somerset, UK
