Soil particulate organic nitrogen as the instable part of soil organic nitrogen,playing an important role in the nitrogen balance,and is of great significance in the growth of plant and the increase of crop yield.In this paper four tillage treatments including conventional tillage with rice only system(DP),conventional tillage with rotation of rice and rape system(SH),no-till and ridge culture with rotation of rice and rape system(LM),and tillage and ridge culture with rotation of rice and rape system(LF) w...