Natural ¹⁵N abundance in plant and soil can be used as a powerful tool to interpret the history of nitrogen fertilization. To investigate temporal variations in N isotopic composition of plant and soil as affected by δ¹⁵N and timing of N fertilization, Chinese cabbages were grown with a single or split N inputs using isotopically different N sources (organic and inorganic) in pot under greenhouse conditions, and analyzed for the δ¹⁵N of plant and soil. Composted manure (δ¹⁵N = +16.4‰) and urea (δ¹⁵N = -0.7‰) were used as organic and inorganic inputs, respectively. Seven N treatments were studied: 1) a single basal fertilization with compost or 2) urea; 3) a basal urea application followed by an additional (at 40 days after transplant, same below) compost or 4) urea application; 5) a basal compost application followed by an additional compost or 6) urea application; and 7) no N fertilization. Irrespective of N application timing, ¹⁵N-enriched organic input resulted in higher δ¹⁵N of cabbage than ¹⁵N-depleted inorganic input. The δ¹⁵N values of cabbages receiving compost were higher than +9.0, while those of cabbages receiving urea were lower than +1.0‰. In case of split N fertilization, the addition of isotopically different N sources in the middle of growth significantly affected the δ¹⁵N of whole plant, while that of isotopically similar N sources did not. Comparing plant δ¹⁵N of cabbage parts, the δ¹⁵N signals of basal and additional N inputs were evident in outer and inner plant parts, respectively. We conclude that measurements of temporal variations in δ¹⁵N of plant parts formed in different growth stages could reveal the history of N fertilization.