The addition of NH4+ increased ARk for the blue clayey paddy soil but decreased ARk for the fluviogenic loamy paddy soil,and for the silt loamy paddy soil it increased ARk at low range of ARk and decreased the ARk value at high range of ARk.

• 加NH_4~+使青紫泥AR~K提高、泥质田AR~K降低、粉泥田在低AR~K时提高而高AR~K时降低;