Many field studies in the tropics carried out by academic researchers have shown that biochar improves soil productivity. (For more details on what biochar is and how it is made, see an earlier article on this site, here.)
Biochar Fund's research did more. It showed that poor farmers typically making less than $300 a year from their crops were able to improve their own yields using simple techniques both for making the char and adding it to the soil.
Average production of maize from this area of Cameroon is about 1.7 tonnes per hectare compared to about 7 to 9 tonnes in the EU or US. If the initial results are replicated elsewhere, the impact of biochar could see yields increase by 40% above what would otherwise be obtained. Read full from source