Think about it. They do not use fertilizer an have been organic for centuries. Where other soils are ruined, Cuba is pristine.

IN 2006, the World Wildlife Fund identified Cuba as the only country in the world to achieve sustainable development. This was, in large part, due to the country’s involuntary adoption and ultimate promotion of agroecology.

See the article in the Boston Globe.

http://www.bostonglobe.com/opinion/2015/04/15/cuba-future-farming/ESYROGF8WARyyRv3lmgNHO/story.html