To investigate whether effects of Al in the sorghum genotypes SCO283 (Al‐tolerant) and NB9040 (Al‐sensitive) are primary effects of Al toxicity, a short‐term experiment was carried out. After 21 days of pregrowth in an Al‐free nutrient solution, plants were exposed to nutrient solutions without or with 10 mg 1‐1Al for 96 h. Nitrogen was supplied as NH4NO3. Twenty four h after Al supply, the relative uptake of all nutrient cations and anions, except NH4+, declined to values varying between 0.8 (K+) and 0.2 (Ca2+, Mg2+). In contrast, the uptake of NH4+was stimulated by Al in both sorghum lines. Total cation uptake and uptake of total nitrogen were balanced by the stimulation of NH4+uptake. As a consequence, excess cation uptake and proton efflux were increased by Al, especially in the Al‐sensitive line, NB9040.