Abstract: Studies on the regularity and mechanism of leaching loss of nitrogen in rice field show thatNO³_--N leaching is the main loss of nitrogen leached from rice field, which reaches to 20kg N·ha^-1 during the planting of double-harvest rice. The sort of nitrogen fertilizer andits application rate have a strong effect on the leaching loss of nitrogen. It's suggestedthat the application rate of fertilizer N should be less than 150kg· ha^-1 for each cropping of rice.

Key words: Nitrogen, Nitric nitrogen, Ammoniacal nitrogen, Leaching loss