Using the method suggested by Silva-Bremner (1966) the absolute content of fixed ammonium in the profiles of paddy soils derived from some major parent materials in Hunan province was studied.
固定态铵绝对含量的剖面分布规律有4种类型:第1类为土壤固定态铵随剖面深度增加而增大;第2类是土壤固定态铵随剖面深度增加而减小;第3类是土壤固定态铵随剖面深度变化不明显;第4类是土壤固定态铵在土壤剖面某一土层中明显增大或减少,特别明显的是犁底层的固定态铵量常比耕作层要高。
