Author(s)

Wenli Li¹, Zhenzhen Zhang¹, Danping Li¹, Chaoyi Guo¹, Yujiang Li¹, Min Yang¹, Xiaojun Shi^1,2,3, Yueqiang Zhang^1,2,3*

¹College of Resources and Environment, Southwest University, Chongqing, China.
²Academy of Agricultural Sciences, Southwest University, Chongqing, China.
³National Monitoring Station of Soil Fertility and Fertilizer Efficiency on Purple Soils, Chongqing, China.

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 < 0.05). The inhibitory degree of NI on nitrification showed the strong tendency at the beginning and then decreased. During the whole experiment, nitrification inhibition rates were 4.4% - 48.5% (En), 6.7% - 9.8% (DMPP) and 5.1% - 97.2% (DCD), respectively. Compared with the control, the application of NI increased the plant height and dry matter accumulation of potted citrus seedlings by 7.6% - 8.6% and 1.0% - 3.8%, respectively. And application of NI also increased the absorption of N by citrus roots and leaves by 9.0% - 17.9% and 0.6% - 7.2%, respectively. Overall, all the three nitrification inhibitors could significantly delay the soil nitrification process in purple soil, with the order of inhibition ability of DCD > DMPP > 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.

Citrus, Nitrification Inhibitors, Soil, Nitrogen

Li, W. , Zhang, Z. , Li, D. , Guo, C. , Li, Y. , Yang, M. , Shi, X. and Zhang, Y. (2018) Effects of Three Nitrification Inhibitors on the Nitrogen Conversion in Purple Soil and Its Effect on the Nitrogen Uptake of Citrus Seedlings. Agricultural Sciences, 9, 655-669. doi: 10.4236/as.2018.96045.