The effect of cow manure and enriched straw on the essential oil, yield and yield components of creeping savory (Satureja spicigera) under dry farming

The health of the food products in different systems is important in terms of the presence of residues of toxins and chemicals and their effect on human health and the environment. Excessive use of chemical fertilizers is one of the main problems of today's agriculture. Organic cultivation of edible and agricultural plants has positive effects on human health (1). The amount of soil organic matter is considered one of the important indicators of soil quality and strongly affects the physical, chemical and biological properties of soil (2). One of the main goals of sustainable agriculture is the use of organic fertilizers in agricultural ecosystems with the aim of reducing the use of chemical fertilizers. Using organic fertilizers instead of chemical fertilizers is effective in ensuring human health and protecting the environment. As a natural substitute for chemical fertilizers, organic fertilizers have a positive and undeniable role in sustainable soil management and ultimately the sustainability of agricultural systems (3). The use of renewable natural fertilizers with biological origin is very important in maintaining the structure, biological activity, water exchange and storage capacity and finally improving the physical and chemical structure of the soil. Today, the most important principle for achieving soil fertility and proper plant nutrition in organic agriculture is the use of organic and biological inputs instead of chemical fertilizers (4). In order to investigate the effect of organic fertilizers on yield traits of Satureja spicigera in Kermanshah rainfed conditions, a factorial completely randomized design with three replications conducted in Agricultural and Natural Resources Research and Education Center of Kermanshah, in 2017-2019. The main factor was three fertilizer treatments including rotten cow manure, enriched straw and field soil (control) and the sub factor was two harvesting (two crop years). The fertilizer treatments applied to Satureja spicigera (savory) plantation in 3×4 m2 plots and in rows with a distance of 50×50 cm. In two agricultural years, morphologic and yield traits including plant height, crown area, plant fresh weight and dry weight of the plant were measured then the fresh yield and dry yield were calculated. Essential oils were extracted from 100 g dried plants based on British pharmacopeia (1993) by Clevenger system. Essential oils were drained by Na2So4, were weighed and EO percentage (w/w) and EO yield (kgha-1) were calculated. Data were statistically evaluated by SPSS (ver. 26) and Minitab (ver. 16) Software’s. The highest fresh yield (2708.49 kgha-1), dry yield (1348.88 kgha-1), EO yield (47.03 kgha-1), plant fresh weight (67.71 g) and the plant dry weight (33.72 g) were obtained in rotten cow manure× second year harvesting. The highest percentage of essential oil (3.70%) was obtained in the treatment of cow manure× first year harvesting. In the PC analysis, the traits of plant fresh weight, plant dry weight; fresh yield, dry yield and EO yield were shown the highest relation to treatment of cow manure and the highest values for them were obtained in treatment of cow manure. The traits of plant height, crown area, plant large and small diameter were had the maximum relation with the enriched straw treatment. None of the examined traits showed a significant positive or negative relationship with the field soil treatment (control).