| The contents of fixed NH+4, NH+4-fixing power, total nitrogen, total phosphorus, total potassium, CEC, pH, exchangeable NH+4, and exchangeable K+ using 24 soils sampled from West areas in China were determined. Correlation analysis were used to study the relationships between fixed ammonium and effecting factors on it. The results showed that the highist content of fixed ammonium was 360 mg/kg, and the lowest was 18 mg/kg, with a average of 179 mg/kg, accounting for 16. 6 per cent total nitrogen. The highest NH+4-fixing power was 54. 0%, and the lowest 6. 0%, with a average of 27. 8%. The NH+4-fixing power, CEC, total potassium, relaxed K+, and invalid K+ were positive and significant related with fixed ammonium separately, but not related with total nitrogen, total phosphorus, pH, exchangeable NH+4, and exchangeable K+. |