A field experiment was done under sandy soil conditions at faculty of agriculture experimental farm, Misurata University, Libya. Examining the influences of varying compost rates (0, 5, 10, and 20 tons/hectare), chitosan concentrations (0, 50, 100, and 200 ppm) beside the combination treatments between them on the growth, yield, and volatile oil production of fennel (Foeniculum vulgare) plants was the primary goal of this study. The results cleared that, when compared with control and the other rates under investigation, using 20 tons of compost per hectare resulted in meaningfully higher values of fennel growth, fruit yield as well volatile oil production. Higher concentrations of chitosan (100 and 200 ppm) significantly improved every attributes observed (plant highest, branches number as well herb fresh and dry weights, fruit and volatile oil yield per plant and per hectare) as compared to the control (chitosan-free spray).  The better values were noticed by the combination treatment between 20-ton compost / hectare and 200 ppm chitosan. Since this combination offers the highest fruit and volatile oil yield advantages, as well as the most profitable rate and concentration, fennel growers might apply it under the same conditions.