Effect of Vermicompost and Chemical Fertilizer on Growth, Herb, Oil Yield, Nutrient Uptake, Soil Fertility, and Oil Quality of Rosemary

Essential oil of rosemary (Rosmarinus officinalis L.) possesses good olfactory properties and is suitable for use in perfumes, soaps, and fragrances. Field experiments were conducted for 2 years (2003-2005) in an area experiencing a semi-arid tropical climate to study the influence of vermicompost and chemical fertilizer on growth, herb, oil yield, nutrient uptake, soil fertility, and oil quality of rosemary. Results from the experiment revealed that among the seven treatments, the application of vermicompost (8 t ha(-1)) + fertilizer nitrogen (N)-phosphorus (P)-potassium (K) (150:25:25 kg ha(-1)) produced optimum herbage and oil yield of rosemary compared with control (no fertilizer) and was found to be on par with application of fertilizer NPK 300:50:50 kg ha(-1). Content and quality of oil were not influenced by vermicompost and chemical fertilizers. Furthermore, it was noticed that available N and P were greater in postharvest soils that received vermicompost alone or in combination with inorganic fertilizers than control (no fertilizer) and inorganic fertilizer-treated soil. This study indicates that combined application of vermicompost and chemical fertilizer helps to increase crop productivity and sustain the soil fertility.