Farmers' knowledge of the contribution of associated trees to soil fertility status in cocoa farms in southern Cameroon.
A comparison of land uses in the South Cameroon area shows that cocoa agroforests are less damaging the environment than the other land uses. In this respect, investigations to assess farmers' knowledge of the contribution of associated trees in the soil fertility status in their cocoa farms were carried out in two ecologically contrasting locations of southern Cameroon in March 2008. 20 cocoa farms were selected per location. In each cocoa farm, all the associated trees were inventoried and their fine roots sampled to assess their mycorhizal status. Individual farmers were asked to rank amongst the identified trees the ten top indicators of fertile soils and to indicate their contributing functional attributes to that effect. The species' frequency and distributions were calculated. Our findings revealed that there were 52 different species in cocoa systems of the forest savanna transition zone against 195 species in the humid forest zone. The frequency distribution indicated a predominance of exotic trees such as Dacryodes edulis, Mangifera indica, Elais guinéensis, Citrus sinensis, Citrus reticuka and Persea americana than indigenous species in both sites. Farmers' classification of species according to their fertilising potentials pertained to some tree functional attributes mainly rooting habits, leaf size and leaf area. Comparison between farmers' ranking and ranking based on species' mycotrophy showed no major differences. Further investigations taking into consideration physico-chemical and other biological aspects influencing soil fertility are necessary to ascertain farmers' perceptions.