Abstract: A pot experiment was carried out to investigate the interspecific nitrogen facilitation between the intercropped wheat and fababean. The results from the isotope dilution method showed that wheat competed more fertilizer N than fababean, and fababean depended more on biological nitrogen fixation. 15N recovery rate of wheat with solid barrier, mesh barrier and no barrier was 58%, 73% and 52%, respectively. Nevertheless, 15N recovery rate of fababean was 30%, 20% and 3%, respectively. The results in the mesh barrier also showed that due to competition from wheat for the soil available N, the percentage of fixed N in fababean was enhanced. The percentage of N absorbed by fababean from pots with solid barrier, mesh barrier and no barrier was 58%, 80% and 91%, respectively. Therefore, the complementary N use did exist in wheat-fababean intercropping, and both the interspecific nitrogen competition and facilitation occurred in wheat-fababean intercropping. At last but not the least, the isotope dilution method showed nitrogen transfer occurred from fababean to the associate wheat, and 5% of total N of fababean was transferred to wheat.

Key words: Wheat, Fababean, Intercropping, Nitrogen transfer, Isotope dilution method, Nutrient competition