A 3 year-plot experiments were performed to determined the possible persistence of the positive effects of treating soil with compost. For this purpose, a sweet sorghum bagasse compost has been used. Experiments were achieved with sweet sorghum (Sorghum bicolor. L. Moench) vr Dale as energy crop. Similar sorghum productivities were obtained both in plots with consecutive compost applications and in plots amended with mineral fertilizers. No residual effect after three years has been detected. It could be due to the low dose of compost application. (Author) 27 refs.