Effects of integrated soil fertility management on the quantitative and qualitative yield of fodder, seed and fennel (Foeniculum vulgare Mill.) essential oil

This study was carried out to investigate different soil fertility management on morphological traits, essential oil yield and quality of fennel (Foeniculum vulgare Mill) forage. The experiment was conducted as a randomized complete block design with three replications at the Research Institute of Forests and Rangelands. The experimental treatments included five fertilizer levels (chemical, biological, vermicompost, 75% and 50% concentration of chemical fertilizers + bio-fertilizers + vermicompost). The results indicated the significant effects of different fertilizer treatments on the traits studied. Accordingly, the treatment of 75% chemical fertilizers with biofertilizers and vermicompost improved morphological characteristics, essential oil yield, and quantitative and qualitative yield of forage, recognized as superior treatment. The above mentioned treatment had the highest plant height (95 cm), shoot dry weight (98 g m-2), biological yield (1191.6 kg ha-1), seed yield (138 kg ha-1), and harvest index (11.6%). The highest and lowest percentage and essential oil yield were related to 75% chemical fertilizers+biofertilizers+vermicompost (about 3% and 18 kg ha-1) and 100% chemical fertilizers treatment (about 2% and 13 kg ha-1), respectively. The highest amount of important forage qualitative traits such as digestible dry matter (%), water soluble sugars (%) and ash content was obtained in 75% chemical fertilizers with biofertilizers and vermicompost treatment. While the above mentioned traits had the lowest amount in the application of 100% of chemical fertilizers, compared to other treatments. In addition, forage quality-reducing factors such as neutral and acidic insoluble fiber had the highest values in this treatment. It seems that in order to achieve sustainable agriculture and optimize the organic production of medicinal plants, the reduced concentrations of chemical fertilizers along with bio-resources can reduce environmental pollution in addition to economic production.