Three soils (light-colored Andosol, gray lowland soil and high-humic Andosol) were placed in 1 m lysimeters. Several types of fertilizers including high-analysis mixed fertilizer, slow-releasing fertilizers, cow manure, and rapeseed meal were applied to each soil, and onion and radish were cultivated. N content and δ^<15>N (natural ^<15>N abundance) in the crops, nitrate leached from a 1 m depth and plow-layer soils were analyzed by an ANCA-SL mass spectrometer. N accumulation by onion was superior in light-colored Andosol, but in contrast, that by radish was the largest in high-humic Andosol. The application of cow manure to the soils increased the amount of leached nitrate compared to the application of chemical fertilizers. Except for a few cases, the δ^<15>N values of onion and radish strongly reflected those of applied fertilizers in light-colored Andosol and gray lowland soil, while the δ^<15>N values of those crops grown in high-humic Andosol showed a small influence by fertilizers. In light-colored Andosol, the δ^<15>N values of leached nitrate were much higher than those of the applied fertilizers, while the δ^<15>N values of the soil were changed by fertilizers. An influence of fertilizer δ^<15>N values on soil δ^<15>N values was observed in the gray lowland soil, although the soil δ^<15>N values were higher than those of the chemical fertilizers. In this soil, the δ^<15>N values of leached nitrate were very close to those of the applied fertilizers. In high-humic Andosol, whose N contents were high, the influence of fertilizers was not observed on the soil δ^<15>N values, while the δ^<15>N values of the crops were close to those of the leached nitrate.
