In recent years awareness of the impacts of intensive agriculture on soil quality and its impacts on the environment has increased. This paradigm increased interest in biological products. In this context, the present trial was conducted to evaluate the performance of two organic fertilizers on onion and turnip crop yield grown in greenhouse. We used two kinds of organic fertilizers made in Portugal, a compost and a chicken manure evaluated in two plant species: onion (Allium cepa L.) and turnip (Brassica rapa L.). Both experiments consisted in a completely randomized design, with the same treatments which are: control (zero application), 1 kg/m2 of compost, 2 kg/m2 of compost, 3 kg/m2 of compost, 5 kg/m2 of compost, 2.65 kg/m2 of chicken manure, 5.3 kg/m2 of chicken manure, 10 kg/m2 of chicken manure, 15.9 kg/m2 of chicken manure, 21.2 kg/m2 of chicken manure. For turnip the evaluated traits were plant weight (Pw), plants length (Pl), number of leaves, and for onion were as follows: plant weight, bulb yields, and bulbs diameter. This study concludes that chicken manure in the dose of 2.65 kg/m2 application represents a sustainable alternative to synthetic fertilizers, mainly in the current challenging situation of agriculture in the context of climate change.