Effects of Three Nitrification Inhibitors on the Nitrogen Conversion in Purple Soil and Its Effect on the Nitrogen Uptake of Citrus Seedlings

Experiments were carried out to study the effects of nitrification inhibitors (NI) on the transformation of soil nitrogen (N) in purple soil and the effects on the N accumulation in different organs of citrus seedlings. In incubation and pot experiments, the rate of nitrification inhibitors 2-chloro-6-trichloro-methyl pyridine (Nitrapyrin), 3,4-dimethylpyrazole phosphate (DMPP) and dicyandiamide (DCD) was 2.4%, 1.0% and 5.0% of N rate, respectively. The trend of different nitrification inhibitors on ammonium nitrogen ( NH+4-N ), nitrate nitrogen ( NO-3-N ) content and pH was compared in incubation experiment; and the effect of different NI on the dry matter quality, N uptake of citrus seedling was studied in pot experiment. The results showed that NI could significantly inhibit soil nitrification in the early culture period (p DMPP u003e En (calculated as nitrogen application rate). Application of NI increased the height and dry matter accumulation, N accumulation of citrus seedling grown in pot experiment. Thus, application of NI would be helpful for improving N use efficiency in purple soil which is one of major soil types for citrus production in China.