The UK currently use 17.5m hectares of farmland. Simon Fairlie, updating the earlier work of the ecologist Kenneth Mellanby finds that while a diet containing a moderate amount (less than we currently consume) 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. Not only do humans need no pasture, but we use grains and pulses more efficiently when we eat them ourselves.
This would enable more than 14m hectares of the land now used for farming to be set aside for nature.
Alternatively, on a vegan planet, Britain could feed 200 million people.
While animal manure might return carbon to the soil, in other respects, contrary to the claims of some practitioners, it is not a great soil additive. One paper reports that the leakage of nitrogen from organic farms using animal manure is 37% worse than the leakage from conventional farming using artificial fertiliser. The problem is timing. While artificial fertiliser often releases its nutrients too quickly, manure releases its nutrients too slowly. If the crop is not to starve, the dung needs to be spread long before the maximum growth spurt. Even then, the plants are unlikely to receive all the nutrients they need to reach their full potential. Nitrogen from manure leaks both before and after crops are able to mop it up.
An analysis by Yadvinder Malhi suggests that between 10 and 50 sq km of land is needed to support one hunter-gatherer, while 10 sq km of modern, productive farming can feed 4,000 people.
Global food production has been comfortably beating population growth for 60 years. In 1961, there were 2,200 kcals a day available for every person on Earth. By 2011, this had risen to almost 2,900. Crop production as a whole has risen much higher: to an astonishing total of 5,400 kcal per person per day. But almost half these calories are lost, mainly through feeding the food to farm animals, but also through using it for other purposes (such as biofuels) and through waste. Even so, in principle, there is more than enough for everyone, if it were affordable and well distributed. So how come chronic hunger has been rising globally since 2015? It’s the result of a lethal combination of inequality and systemic instability in global food distribution.