A strict two-factor field ‘Mister’ yellow lupin experiment was made in a split-plot design in poor rye complex soil (soil valuation class IVb) at the Experiment Station of the Faculty of Agriculture and Biotechnology, the University of Technology and Life Sciences at Mochełek over 2008-2011. The experiment design covered 2 factors: growing yellow lupin after intercrops of ‘Bardena’ white mustard and ‘Pastar’ winter rye as well as seed inoculation with Bradyrhizobium lupini with or without genistein added. Growing intercrops in the poor rye complex soil considerably decreased neither the Nmin content in early spring nor the size of nodulation in yellow lupin. After lupin harvest, slightly more Nmin was noted for the treatments where intercrops were applied, especially rye in the 0-30 cm layer. The weather pattern, especially moisture conditions, pointed to a special sensitivity of nodulation to water deficit or excess in the rhizosphere. The method of preparing seeds for sowing did not play a greater role in developing the Nmin content in both soil profile layers analysed. White mustard showed a negative effect on the dry weight of nodules and the total N content in the plants and the seeds of yellow lupin as well as created the least favourable conditions for the survival and the capacity for symbiosis by symbiotic bacteria remaining in soil after lupin harvest. The state of yellow lupin plant nitrogen nutrition did not depend on the experimental factors.
