Onion plants (Allium cepa L. var. Baia Piriforme Precoce de Piracicaba) were grown in pots containing 1 kg of pure quartz. Twice a day they were irrigated by percolation with nutrient solution. The treatments were: complete solution, -N, -P, -K, -Ca, -Mg and -S. The plants showed deficiencies symptoms in the following order: N, Ca, P, K, Mg and S. The deficiencies were comproved by chemical analysis of the different parts of the plant. The percentage of macronutrients in dry matter are expressed on the Table 3 in Portuguese text. "Levels" found in percentage of dry matter were: The amount of nutrients exported per plant, in mag, were: N-657.7; P-84.1; K-992.4; Ca-102.2; Mg-72.9; S-167.7.