A large amount of nutrients coming from feces of seabirds which feed on mostly fishes in offshore is inputted into the terrestrial ecosystems near their breeding colony. It is well demonstrated that nutrients input by seabirds strongly affect species richness and biomass of plants in the forests or grasslands. However, the effects of the nutrients input into the plants at the farmland near the seabird colony have rarely been examined. The rice-fields and the irrigation pool lie near the colony of Great Cormorants Phalacrocorax carbo in Aichi, Japan. In this study, spatial variations in the proportion of nitrogen content (N%) and nitrogen stable isotope ratio (δ¹⁵N‰) of the soils and plants, and the heights of the plants at the drained rice-fields in winter were examined. Both soil and plants represented higher N% and δ¹⁵N‰ in the fields closer to the irrigation pool. Moreover, those ratios were even higher around the inlet of the irrigation waters. These results indicated that cormorant-derived nitrogen could be inputted into the rice-fields via irrigation waters. The plants representing higher N% and δ¹⁵N‰ had taller vegetation heights. These results also suggested that the cormorant-derived nitrogen could increase the growth of the plants in the rice-fields.