Experiment was conducted for five successiveyears under large undisturbed monolith lysime-ters(2m×2m in square,l m in depth).Thesoil was silty clay loam texture and had a con-tent of total N 1.55 g/kg.The soil was flood-ed with penetration rate controlled at approxi-mate 3 mm per day in duration of double-riceseason and laid fallow and natural in winterand spring.Results showed that nitrate was the mainform of nitrogen in percolates.The change of The experiment was conducted for five successive yeasts under large undisturbed monolith lysime-ters (2m × 2m in square, lm in depth). The soil was silty clay loam texture and had a con-tent of total N 1.55 g / kg. The soil was flood- ed with penetration rate controlled at approxi-mate 3 mm per day in duration of double-riceseason and laid fallow and natural in winterand spring. Results showed that nitrate was the mainform of nitrogen in percolates. change of