Abstract: The index of nitrogenous fertilizer application and nitrogen balance for high yield in seashore rice region of Hebei by using ¹⁵N were introduced in this paper. The results of pot-culture and field experiment for 3 years are as follows: 150-165kg of pure nitrogen per ha were applied in middle fertility soil, 1/2 or 1/3 of them were applied as base fertilizer, the other two 1/4 were applied at both tillering and booting stages. The fertilizer should be applied in 0-10cm deep. The yield per ha was over 9000kg. The utilization ratio of nitrogen was 33%, its residue ratio in soil-28%, and the loss ratio-39%. This study provides not only the technology of rational application of nitrogen for rice, but also the basis for scientific application of nitrogenous fertilizer.

Key words: 15N tracing, Nitrogen balance, Rice