Since July 1996, ORSTOM researchers have been conducting some fieldworks in three villages situated along the west coast of Santo. F. Tzerikiantz has settled there for consecutive three month periods, alternatively in Wusi area and Elia area. while A. Walter has regularly visited Wusi. Elia and Tasmate. The main purposes of this research is to study the traditional agricultural systems and to document the techniques and practices enabling root crop cultivation. The main topics are the origine of root crops and the manipulation of their variability by local farmer (taro and yam in these areas). the diversification of root crops through subsistence cultivation, the transformation of cultural practices and the possibility of cultural intensification. During nearly two years of study we have collected good data on wet-taro cultivation and on yam shifting cultivation in Wusi and Elia. Quantitative data on taro and yam yields, in both contexts, have also been collected. Then we have conducted a food consumption survey in order to determine the total amount of root crops harvested and consumed for domestic purposes. The aim was to compare the root crops production with the family consumption and to point out which portion of each crop was involved in the diet. This field report is restricted to a brief analysis of the data collected during this last survey.