Cereal grain yield and biomass production are affected by fertilizer application strategies. In order to quantify the performance of wheat, rye and triticale cultivars for use as energy crops, field experiments with either modified phosphorus-potassium or potassium applications were designed at two locations in Denmark over a 3-year period. Five wheat cultivars ('Astron', 'Herzog', 'Kosack', 'Kraka' and 'Ure'), two winter rye cultivars (the population cultivar 'Motto' and the hybrid cultivar 'Marder) and the triticale cultivar 'Alamo' were selected. The grain and straw fractions were analysed for biomass, ash and contents of nitrogen (N), K, Cl, sulphur (S) and Na. Dry matter yields varied between 11.5 and 15.9 t ha(-1) at the two locations. Triticale and rye had a higher total dry matter yield than wheat, even at lower inputs of N fertilizer. Thus, the constant high yield of rye and triticale is an advantage for biomass for energy purposes. The mineral content of the grain fraction changed only little between years and locations. By contrast, large variations in the analysed ions in the straw fraction between years and locations were observed. The use of K fertilizers resulted in a significantly increased concentration of K in the straw. However, this increased concentration was eliminated in years with high precipitation in the final 3 weeks before harvest, where substantial amounts of K, Cl and S were removed. The results are discussed in relation to the possible use of grain crops for energy production. (c) 2007 Elsevier Ltd. All rights reserved.