From Fred White, Nottingham, UK
Neither your article on the impact of food production on the planet nor the editorial that accompanied it mentions the health and maintenance of the largest biome bar the ocean: soil. It is unlikely that wheat yields could increase by 18 per cent by 2100 if farmers keep doing what they are doing unless you could coax a crop from something that will, by then, resemble Martian regolith. A healthy soil structure is essential, if nothing else, for management of water retention and drainage (16 November, Leader and p 44).
