Two field experiments were carried out during two successive summer seasons of 2008 and 2009 at the experimental farm, El-Kassasein Research Station, Ismailia Governorate, to investigate the effect of different rates of farmyard manure (10,20,30 and 40 m³/fed), plant spacings (20,30,40 and 50 cm) and their interactions on vegetative growth, fresh and dry weight, yield and its components and chemical constituents of Jerusalem artichoke plants (Helianthus  tuberosus  L.) cv. fuseau under sandy soil conditions. Farmyard manure at a rate of 40m³/fed. recorded maximum values of plant height, number of shoots /plant, fresh and dry weight/ plant, and increased   number of tubers per plant, average tuber weight and yield / plant as well as chemical constituents of tubers as compared with 10m³/faddan. Planting Jerusalem artichoke plant at 50 cm reflected the highest values of vegetative growth parameters, yield and yield components as well as chemical constituents of tubers. The best interaction treatment between different rates of farmyard manure and plant spacing was fertilization with 40m³ farmyard manure in combination with the highest plant spacing (50cm) as compared with other treatments.