Short-term effect of biochar on the improvement of calcareous soil biological properties and marjoram (Origanum majorana L.) growth under greenhouse conditions in a Mediterranean climate

In the cultivation of medicinal and aromatic plants may be possible to improve the biological properties of the soil and to grow plants with properties close to those in the natural environment by using the valuable organic matter resources obtained by special methods such as biochar in an economical. In this study, oak wood biochar (OBC) was used as fertilizing material for aromatic marjoram cultivation and applied to soil as follows: 0 t ha-1 OBC-control (OBC-0), 20 t ha-1 OBC (OBC-2), 40 t ha-1 OBC (OBC-4), 60 t ha-1 OBC (OBC-6), 0 t ha-1 OBC + chemical fertilizer (OBC-0+CF), 20 t ha-1 biochar + chemical fertilizer (OBC-2+CF), 40 t ha-1 biochar + chemical fertilizer (OBC-4+CF), 60 t ha-1 biochar + chemical fertilizer (OBC-6+CF). Afterwards, the effects of the applications on the biological properties of the soil where marjoram is grown and the physical properties of the plant, volatile oil yield and oil components were investigated. Accordingly, it was determined that the number of bacteria and enzyme activities (dehydrogenase, urease, alkaline phosphatase, β-glycosidase) of the soil reached ​​with the biochar applications alone. It was determined that the application that increased the green herb yield the most with the fresh and dry weight of marjoram was the application of the biochar with chemical fertilizer added. On the other hand, in contrast to the addition of chemical fertilizers, it was determined that the application of biochar alone increased the volatile oil rate and the amount of carvacrol and thymol in the plant.