Effects of vermicompost, compost and digestate as commercial alternative peat-based substrates on qualitative parameters of Salvia officinalis

Peat is a common substrate used for the cultivation of potted plants. However, the use of peat in horticulture has recently been questioned from an environmental standpoint, since it is a non-renewable resource and plays a major role in atmospheric CO2 sequestration. The aim of this work was to assess the potentialities of substrates obtained from vermicompost, compost and anaerobic digestion processes to partially substitute peat for sage (Salvia officinalis L.) cultivation. Therefore, we planned an experiment to assess the effect of these substrates on essential oil (EO) yield and composition, as well as on leaf nutrients concentration of sage plants. The three substrates were mixed with commercial peat (Radicom) at a ratio of 40% of alternative substrates and 40% of commercial peat. The chemical properties of the alternative substrates did not affect the leaf content of macro and micronutrients, as well as of heavy metals. Moreover, the EO yield and quality was not affected by the substrates and did not differ among them. Results provided evidence that the three alternative substrates can be used to partially substitute peat in soilless cultivation of sage plants. However, due to the higher values of the electrical conductivity of the substrates obtained from composting and anaerobic digestion processes, such substrates must be used with caution.