Carbon dioxide isn't the only greenhouse gas that's a threat to the planet. Nitrous oxide, emitted when farmers fertilise their fields, is a growing climate change threat as well. We find out about an environmentally-friendly potential solution.

Also, in Africa the agriculture sector wants more fertiliser so that farmers can boost crop yields; a controversial new novel about a Mexican woman forced to flee from drug cartels shines light on the world of American publishing; on the border between Venezuela and Colombia, a Colombian volunteer opens up her home to desperate migrants; and on opposite sides of the world, two guys try to make a planet Earth sandwich.

(David Melevsky, owner of Go Green Organic Land Care, treats grass areas that have been reseeded to repair winter damage with fertilizer at Ocean Park Meadow condos. Credit: Derek Davis/Getty Images)