The aim of this investigation was to optimise the yield percentage of blue lupins in mixed cropping systems. Field experiments were conducted at two locations in Northern Germany (Institute of Organic Farming near Hamburg and Institute of Plant and Soil Science at Braunschweig). Two types of blue lupins, the determinate and branched type were cultivated together with spring barley, spring wheat or fodder peas in different seeding ratios (SR): 50% : 50%, 62,5% : 37,5 % and 75% : 25% of the respective pure cropping seeding rate. We present data on total grain yield, yield of blue lupins, yield percentage of blue lupins, protein content, and protein yield. Total grain yield decreased with increasing SR of blue lupins whereas, in contrast, the yield of blue lupins, protein content and protein yield increased. This shows the low competitive ability of blue lupins against the mixed cropping partners, particularly cereals. Therefore, the yield percentage of blue lupins in mixed cropping with cereals did not reach more than 25%. From the view of plant production and the purpose of animal nutrition the percentage of grain legumes should be higher and comparable to those of other crop mixtures like peas with spring barley or beans with oat
