From Live Science. Two new maps released Jan. 16 considerably improve estimates of the amount of land farmed in the world — one map reveals the world's agricultural lands to a resolution of 1 kilometer, and the other provides the first look at the sizes of the fields being used for agriculture.
The researchers built the cropland database by combining information from several sources, such as satellite images, regional maps, video and geotagged photos, which were shared with them by groups around the world. Combining all that information would be an almost-impossible task for a handful of scientists to take on, so the team turned the project into a crowdsourced, online game. Volunteers logged into "Cropland Capture" on a computer or a phone and determined whether an image contained cropland or not. Participants were entered into weekly prize drawings.