The soil preparation in horticulture, including organic, is characterized by intense soil tillage, which
increases energy costs and unbalanced the environment. The organic system in onion cultivation has shown
satisfactory results, however the soil covering use tends to improve the cultivation environment and may result in higher yields. The objective of this work was to evaluate the performance of onion cultivars in organic cultivation under different soil coverages. The experiment was conducted in the period of April to October of 2009, under protected cropping, in the experimental area of the horticulture sector of the Universidade Federal do Acre (UFAC), in Rio Branco, Acre, Brazil. A randomized block design was adopted, in a split-plot arrangement, the plots being comprised of soil coverings: coffee bean husks, grass straw (Brachiaria decumbens); dessicated
bamboo leaves (Bambusa spp.) and uncovered soil (control treatment), and the subplots comprised of three
onion cultivars (IPA 10, IPA 11 and IPA 12), with four repetitions. The variables analyzed were total bulb yield
(t ha-1), marketable bulb yield (t ha-1), fresh mass of the bulb (g bulb-1), classification of the bulbs and loss
of mass as a function of storage time. There was no interaction effect between the soil coverings and the cultivars. Cultivars IPA 10 and IPA 11 showed greater agronomic performance of the studied variables. The soil
coverings did not affect the yield and average mass of the bulbs under organic cultivation. The three cultivars
presented more than approximately 70% of the bulbs in class 2 and a maximum of 5% of unmarketable bulbs. The loss of mass after 49 days of storage was 10% independent of the cultivar or soil covering.
