This investigation  was carried out  at the experimental  farm of the faculty of Agriculture , Menoufiya  Univ at Shiben El-Kom  during to growing  the seasons  of 2016/2017  and 2017/2018 for studying  the effect of some cultural  treatments  such as irrigation  with magnetic water and bio and ammonium nitrate fertilization levels  individually or in combinations  on the vegetative growth parameters , essential oil content and some chemical constituents  of Majorana hortensis L. plants. The obtained results showed that the growth parameters such as plant height , number of branches  per plant  , fresh and dry weight  per plant  as well as per feddan  were markedly  improved as a result of watering Majorana hortensis L.  plants with magnetic water besides using bio fertilizers ( Rhizobium,  Azotobacter and Azospirillium )  plus ammonium nitrate fertilization  at its different rates ( 0 , 100 , 200 and 300 kg/fed ) .  The best results in this respect  were obtained by using magnetic water , Azotobacter fertilizer application  and the moderate  level of ammonium nitrarte fertilization ( 300 kg /fed ) .  Furthermore ,  the highest essential oil content , NPK percentages  as well as photosynthetic  pigments concentrations and total carbohydrate content were realized by  the same treatment in the two growing seasons . On the other hand the control treatment ( irrigation  with ordinary water  without using either bio or chemical  fertilizer ) gave the lowest growth and yield parameters as well as the lowest chemical constituents of the plant in the two experimental seasons .