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.
Given the rising cost of artificial fertilisers, the need to stop using the fossil fuels from which they are made, and declining insect populations, the organic option is looking increasingly attractive. Were it to come to pass, the remaining 11m or so hectares of grassland would be open to a variety of land uses, such as nature recovery, grazing cattle and sheep, planting more trees, energy crops and so on.
My guess is that rather than choosing to rewild all of it, as Monbiot suggests, most people would prefer a diverse, multifaceted landscape supporting a thriving rural economy.
Simon Fairlie
Bridport, Dorset
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