1. Forms and Amount of Nitrogen in Soil; Wen Qi-xiao. 2. Natural 15N Abundance in Soils; Xing Guang-xi, et al. 3. Mineralization of Soil Nitrogen; Zhu Zhao-liang. 4. Fixation and Release of Ammonium; Wen Qi-xiao, Cheng Li-Li. 5. Adsorption and Diffusion of Ammonium in Soils; Chen Jia-fang. 6. Nitrification; Li Liang-mo. 7. Biological Nitrogen Fixation; Yao Hui-qin. 8. Denitrification; Li Liang-mo. 9. Ammonia Volatilization; Cai Gui-xin. 10. Nitrogen in the Rhizosphere; Liu Zhi-yu. 11. Fate and Management of Fertilizer Nitrogen in Agroecosystems; Zhu Zhao-liang. 12. Transformation and Management of Manure Nitrogen; Cheng Li-li, Wen Qi-xiao. 13. Nitrogen Management and Environmental and Crop Quality; Ma Li-shan. 14. Nitrogen Balance and Cycling in Agroecosystems of China; Zhu Zhao-liang.