this helps water permeate the soil and promotes the growth of beneficial natural tillers, like earthworms. the second is maintaining soil cover. in africa, people often sweep their fields clean, removing the natural crop residues, then make a pile of them and burn them. conservation farming teaches them to save this valuable mulch. covering the land stops evaporation, gives nutrients back to the soil, and protects the ground from the torrential rain that sometimes falls here. the third is to intercrop grains with nitrogen-rich legumes, like beans or peanuts, and eventually even trees. in this model field of the golden valley agricultural research trust north of the capital city lusaka, the trees fix nitrogen into the soil. >> this is a technology which should be promoted in africa because it can answer a lot of problems to a small-scale farmer. 80% of the food produced for the country comes from a small-scale farmer, and conservation farming can be an answer to some of the most expensive inputs, like the fertilizers, which farmers are really struggling to get to produce food. >> little li