Idea: Farmer managed natural regeneration (FMNR), which restores existing trees on drought-stricken land, to improve Senegal's dwindling harvests.

Problem: Senegal is suffering its third drought of the decade, resulting in reduced crops and inflated food prices. The World Food Programme assisted more than 9 million people in the Sahel region of West Africa this year, including 800,000 in Senegal.

Method: Attempts to tackle the resulting problem of soil fertility have largely flopped so far. Trees planted as part of reforestation schemes have seen only a 5% success rate and fallowing is not an option, with 80% of African farmers owning under two hectares of land, which need to be utilised year in, year out. This puts the emphasis on reinvigorating the stumps of nitrogen-fixing trees, which were formerly cleared to maximise crop space. Farmers are thus encouraged to prune the stems and branches of trees like Faidherbia albida, giving new life to the vegetation already there.

Verdict: FMNR is an inexpensive way for farmers to make improvements with the resources they already have, increasing millet harvests from 430kg to 750kg a hectare, and saving money on fertilisers, with restored trees producing leaf litter (forming humus) and giving shade to livestock (for manure). It gives the ecosystem a holistic boost, encouraging wildlife like bush pigeons and rabbits to return, and providing welcome human benefits such as wood cuttings for cooking and new food sources such as tamarind. Mina Holland