Effects of different nitrogen regulators on nitrogen transformation in different soil types

Laboratory incubation experiments were conducted to compare the inhibitory effects of dicyandiamide( DCD) and 3,5-dimethylpyrazole( DMP) on nitrification in meadow-cinnamon soil and fluvo-aquic soil,the main soil types of North China Plain. The synergistic effect of DMP combined with urease inhibitor hydroquinone( HQ) on nitrogen transformation in fluvo-aquic soil was further studied. The results indicated that,in contrast to DCD,DMP had a stronger inhibitory effect on the nitrification in the two tested soils. In comparison with the treatment without any inhibitor,the soil NH4+-N content in the treatment with DMP increased significantly by 149. 5%-387. 2% at the peak of nitrogen transformation stage,and the soil NO3--N content reduced by 22. 3%-55. 3%. The inhibitory effects of DCD and DMP in fluvo-aquic soil were both stronger than in meadow-cinnamon soil. In addition,the application of DMP combined with HQ had a significantly synergistic effect on soil nitrogen transformation.