Simple Solutions Feed Hungry People

Farmers in eastern Africa gave up pulling weeds. Now they plant weeds along with their crops and, as a result, harvest 60 to 70 percent more food than before. The idea was developed at the Mbita Point research station in Kenya. The logic of this technique is simple: give the insects something to eat so they don't need to graze on valuable maize.
Mexican farms raise their yield by planting squash and beans in with the maize. When crops are combined there is less damage from insects and more efficient use of water.
In Bangladesh rice paddies double as fisheries, with results so successful they are being implemented in other countries.
- Jane Hersey, Pure Facts newsletter, The Feingold Association.
[I am far from an expert, but if this really works not only in short term, but long term I wonder why great ideas like this do not spread like a fire in every part of the world?]