Content of Nitrogen, Phosphorus, and Potassium in Oregano (Origanum vulgare L.) Cultivated in Substrate

The aim of this study was to determine the accumulation of above-ground biomass and nutrient removal of N, P, and K in oregano (Origanum vulgare L.) plants under five nutrient solution concentrations. The experiment was set up in a shade house located in Xalisco, Nayarit, in western Mexico during the Spring–Summer 2011, using a commercial variety of oregano. A randomized complete-block experimental design with five replicates and a time series arrangement was used. The harvest days were 20, 40, 60, 80, 100, and 120 days after transplant (DAT)—dates that shoots 15 cm in length, the required size in the international market—were obtained. Steiner solution was used at five concentration levels: 25%, 50%, 75%, 100%, and 125%. The growth medium was volcanic slag with 0.3–1 cm granulometry. Plant height, fresh and dry plant biomass and stem diameter were assessed. Nutrient content of nitrogen, phosphorus and potassium was determined in the different samples in order to understand the absorption dynamics of these elements under commercial management.  The results showed that the 75% NS concentration increased plant height (PH) by 35%. Stem diameter (SD) had no significant differences among treatments. Above-ground fresh biomass (AGFB) and above-ground dry biomass (AGDB) were increased by 57.8% and 65.62% respectively. Nitrogen, P, and K (mg/kg) removal was dependent on the ionic concentration of the nutrient solution. In general, the economic yield (leaves) of oregano depends on the nutrient solution concentration.