There's a patch of ground roughly twenty meters wide near the town of Harpenden, half an hour's train ride north of London. Many such patches are found nearby, but this lawn, a short walk from the red-bricked gables of Rothamsted Manor, is a sliver of English meadow as it may have been more than 250 years ago. It's also Plot 3 of the famous Park Grass experiment that John Bennet Lawes founded in 1856 and is still going strong.
Lawes and his collaborator John Henry Gilbert began their experiment to test whether fertilizers could be used to boost the production of grass for making hay. To this end, they divided up a meadow that had been in grass for at least a century, and treated each twenty-meter strip with a different array of fertilizers.
Some received old-fashioned manure, while many others received the newfangled inorganic kind with which Lawes had ...
