Аннотация:Calendula officinalis is classified as one of the most important medicinal crops that deserve improvement in production and quality. This research study was conducted to investigate the effect of using compost, as an organic amendment, to replace some of the mineral fertilizers normally used. The experiments were conducted in the open field in two successive seasons 2016-2017 and 2017-2018 at Applied Research Center for Medicinal Plants, National Organization for Drug Control and Research, (NODCAR) at Kafer El- Gable, Giza. Pots which were filled beforehand with sandy soil received six treatments: (1) 100% Organic (Org), (2) 100% Mineral (Min), (3) 75% Min + 25% Org, (4) 50% Min +50% Org, (5) 25% Min +75% Org + (6) (control) without fertilizer. Mineral fertilization (NPK) showed the highest values of both vegetative and chemical characteristics studied of Calendula officinalis var Costa yellow. Application of compost at the rate of 25% or 50% showed closer values to those obtained by the recommended dose of NPK. Thus, possibility of replacing mineral fertilizers to reduce environmental impact can be substituted by 25% to 50% compost.
