Response of caraway (Carum carvi L.) growth, yield, and essential oil content to organic fertilizers as substitutes for chemical fertilization

Caraway is a medicinal and aromatic plant valued for its essential oil, yet its yield and oil quality are highly sensitive to nutrient availability. Heavy reliance on chemical fertilisers increases production costs and contributes to environmental degradation, while the potential of organic fertilisers remains underutilized. Based on this, a field experiment was conducted at the College of Agriculture in Fayoum, Egypt, during the 2021-22 and 2022-23 seasons. This work aims to investigate the effects of single additions of organic fertilizers, cattle and poultry manure and of combined additions of organic fertilizers with mineral fertilizers on the growth, yield, chemical composition, and essential oil content of caraway plant. The three amendments were applied at five rates: 0, 25, 50, 75 and 100% alone or in combination as dual or triple treatments. The results showed that integrating a mixture of cattle and poultry manure (50%) with mineral fertilizers (50%) on caraway plants significantly increased seed yield and essential oil yield, as well as yield per plant and per hectare. Moreover, the highest number of umbels was observed without the use of any mineral fertilisers (i.e., 50% of both cattle and poultry manure). As well as cattle and poultry manures, these can be mixed with mineral fertilizers and yield the highest results in all studied parameters of caraway plants, without depending entirely on chemical fertilizers. Hence, it is highly advisable to mix the organic manures (cattle and poultry) along with 25% of mineral fertilisers to help reduce the side effects and the problems of the chemical fertilizers and to achieve the highest results of most organically produced caraway yield.