George Monbiot (On a vegan planet Britain could feed 200 million people, 13 May) quotes me as calculating that “while a diet containing a moderate amount of meat, dairy and eggs would require the use of 11m hectares of land (4m of which would be arable), a vegan diet would demand a total of just 3m”.
He doesn’t point out that these figures relate to chemical agriculture using artificial fertilisers and pesticides – practices that he later says he doesn’t support. I also made estimates for organic vegan agriculture with green manure being ploughed directly into the soil, and for organic husbandry in which green manure is fed to dairy cows whose manure is composted, while pigs and chickens are substantially fed on food waste. Both systems require about 6.5m hectares of arable land to provide a healthy diet for everyone in the country. The vegan system is slightly more efficient in its land use, while the livestock system provides a more varied diet.
