Effect of soil fertilization systems on yield quality of fennel (Foeniculum vu/gare Mill) a medicinal herbaceous plant was carried out in field experiment, in Alborz research center, Karaj/Iran in 1996-97. The treatments were various levels of chemical fertilizers (N.P.K), used in commercial agricultural systems, different levels of manure, used in sustainable (organic) systems, mixture of different ratios of fertilize and manure and without fertilizer and manure (control). The experiment was conducted using completely randomized block experimental design with three replications. The experiment showed that the intermediate treatment "30 tonha-1 of manure mixed with N=80, P=64 and K=80 kgha-1 of chemical fertilizers" produced the highest amount of essential oil with 3.182, percent. The main essential oil components of fennel seed including anethole, fenchone, limonene and methyl cervical were studied. The anethole as the most important component of the essential oil, in treatment "20 ton ha-1 of manure mixed with N=40, P=28 and K=40 kgha-1 of chemical fertilizers" had the highest amount and increased by 74.38%. Thus, the anethole in the above treatment comparison to the control, chemical and organic treatments, increased by 36. 10, 28.06 and 20.75 percent, respectively. Based on the results of this experiment, the intermediate soil nutrition system (fertilizer and manure) was introduced for sustainable agriculture.