Your series on solving world hunger in the future (Nature 466, 531 and 546–561; 2010) focuses mainly on biological measures. Better management of soil and cropping systems could improve productivity right away, with minimal environmental threat.

Reducing soil disturbance is crucial to sustainable crop production in most environments. The principles of no-tillage, permanent soil cover and rotation need less energy and pesticide input than tillage-based alternatives, and are the foundations of conservation agriculture, which inhibits wind and water erosion.

Large grain harvesters flatten the soil with an axle load of 18–20 tonnes each — about twice that allowed for heavy trucks. Driving these loads over soil destroys porosity and productivity, so tillage seems the only option. Yet compaction can be avoided by no-till cropping of permanent beds in controlled-traffic farming systems, in which the wheels of heavy machinery are restricted to hard permanent traffic lanes (see http://www.ctfsolutions.com.au).