Africa has good soils and could easily feed itself if more money was spent on fertiliser and seed rather than food aid, says one soil scientist.
He says in 2005 Malawi's maize harvest only reached 57% of the country's requirement, with about 5 million Malawians requiring food aid.
Sanchez says since then, the government has begun subsidising farmers to buy fertiliser and improved maize seed.
In 2007, maize yields almost tripled at the national scale, transforming Malawi into a food exporter, he says.
Sanchez says the subsidy programs are now being extended to another 11 countries in Africa including Tanzania, Kenya, Ethiopia, Uganda, Mali and Nigeria.
He says the gains in yield are similar to those seen in India and the Philippines at the start of the Asian green revolution.
By contrast, yields from highly-subsidised farmers in North America are around 10 tonnes per hectare....