In Africa, different forms of organic agriculture exist, particularly in Cameroon where uncertified natural farming systems have a prominent place. Recognition of such systems by public policies has been limited due to a lack of statistical and experimental data. To address this issue, we use a probabilistic elicitation of expert knowledge to assess the performances of natural cassava and plantain systems in the Centre Region of Cameroon. In total, 55 experts were interviewed to compare the effects of natural and conventional agriculture on local food security through three key indicators: average yield, farm-gate prices, and labour quantity. Our results showed that the yields of natural agriculture were generally lower than conventional yields while the farm-gate prices of both types of system were similar due to the absence of a specific market for natural farming. Additionally, the amounts of labour elicited by farmers were more variable in conventional systems than in natural systems.