Boston Calling

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)