The effect of urea fertilization on the yield and oil of medicinal plants , sweet cumin, fenugreek, coriander and anise, which are always cultivated

Seeds of sweet fennel, anise, coriander, and fenugreek were planted in the Mosul Dam area on 20/12/2017 under rain-fed conditions, with the application of nitrogen fertilization in the form of urea. Fertilizers were broadcast on 21/1/2018, and the seeds were harvested starting from 2/6/2018. The percentage of active essential oils was estimated using a Soxhlet apparatus, with two types of organic solvents—petroleum ether and ethyl alcohol—employed. The volatile oil content was measured according to the A.O.A.C. method, commonly used for estimating elements, oils, carbohydrates, and other compounds.

The results were statistically analyzed using a Randomized Complete Block Design (RCBD) and processed via the SAS software (SAS, 1985). Means were compared using the LSD test at a 5% probability level. The statistical analysis revealed that coriander significantly outperformed the other cultivated plants in terms of yield per dunam, primarily due to anise's lack of drought tolerance, as the cultivation relied solely on rainfall. Additionally, sweet fennel showed a significantly higher oil production compared to the other plants.

The study aimed to evaluate the success of rain-fed cultivation for these species and assess whether rain-fed agriculture, supplemented with nitrogen fertilizers, is economically viable. It also examined the impact on productivity—both quantitatively and qualitatively—as well as the percentage of volatile oils in the four species, which play a crucial role in producing antioxidants and phenolic compounds with significant medicinal value.