LAUSR

Abstract Organic fertilizers might have prominent effects on lavender (Lavandula angustifolia Mill.) plant growth and secondary metabolites composition. A field study was conducted to assess the responses of biomass yield, nutrients, and essential oil components of lavender to different organic fertilizers. The effect of fertilizer treatments included changing the amounts of cow manure (0–40 tonne/ha) and vermicompost (0–15 tonne/ha). The fertilizers enhanced the total area and dry matter of the leaves by 40% with cow manure and 62% with compost compared to no fertilization. The essential oil yield increased by 70% after treatment with cow manure. The highest change in the essential oil composition was marked in the oxygenate monoterpenes such as 1,8-cineole, followed by borneol, and camphor. The highest percentage of 1,8-cineole was achieved with a mix of both organic fertilizers. In addition, this combination was able to increase the leaf N concentration by 43% above the unfertilized treatment. These results showed that the use of combined fertilizers enhanced the leaf dry matter and improved the plant nutrient value and essential oil constituents.