The Changes in Yield and Chemical Profile of Essential Oil and Leaf Minerals of Satureja macrantha C.A.Mey. Under Combined Manure and NPK Fertilizer

The use of environmentally friendly fertilizers is a new strategy to subside the undesirable effect of chemical fertilizers. The field experiment was conducted to investigate the effect of cow manure and NPK fertilizers on physiochemical characteristics and nutrients accumulation of Satureja macrantha C.A.Mey. in a randomized complete block design (RCBD) in three replications. Cow manure and NPK (20, 20, 20) were used in four levels as cow manure (60 t/ha), NPK fertilizer (50: 25: 25 kg/ha), combined cow manure (30 t/ha) and NPK fertilizer, and untreated treatment (control) in Karaj, Iran, during 2017 and 2018. The results showed increased dry weight yield under manure or the combined NPK and manure fertilizers in second year. The relative water content (RWC) in second-year plants treated with manure was higher compared to other experimental treatments. Essential oil percentage increased by manure application and its combination with NPK fertilizer, ranging from 1.06 to 1.86%. Essential oil yield of aerial parts of S. macrantha under organic manure in the second year was significantly higher in comparison with control and NPK-treated plants. The GC/MS analysis showed that the main essential oil compounds of S. macrantha were p-cymene (22.14%-33.78%), γ-terpinene (21.7%-35.22%), and thymol (13.1%-37.9%). The minerals in aerial parts of S. macrantha were changed under fertilizers and year. Manure and its combination with NPK fertilizer significantly improved phosphorus (P), and potassium (K). Both NPK fertilizer and cow manure significantly led to increased calcium (Ca) concentration in second-year plants. NPK fertilizer had negative effect on iron (Fe) in second-year plants, but the enhanced Fe was observed in the second year when plants treated with cow manure. The present study recommended the combined use of manure and NPK fertilizers to reach the optimum essential oil of S. macrantha.