At present, various nitrification inhibitors have been found, including synthetic nitrification inhibitors and biogenic nitrification inhibitors. The nitrification can be inhibited by competing with AMO of ammonia-oxidizing microorganisms for substrates, chelating the active site of AMO, or other functions such as inhibiting other proteins by product oxidized by AMO. Nitrification inhibitors not only play an important role in improving the efficiency of nitrogen fertilizer and crop yield, reducing nitrate leaching and N2O emission, but also play an important role in the study of microbial mechanism of nitrification.
At present, the mechanism of some nitrification inhibitors (such as DMPP, Nitrapyrin) is still controversial. In the future, the mechanism of nitrification inhibition should be further studied by combining the methods of molecular biology and biochemistry, so as to better evaluate and use it. Besides, the effect of nitrification inhibitors is affected by a variety of factors such as soil type, soil pH, temperature, humidity, etc, resulting in poor effect of nitrification inhibitors in practical application. Meanwhile, studies on the physiology and ecology of nitrifying and microorganisms revealed that the response and sensitivity of different ammonia-oxidizing microbial groups to various nitrifying inhibitors were different. The dominant groups of ammonia-oxidizing microorganisms are different in different soils. It may be the key cause of the difference in the inhibitory effect of nitrification inhibitors in different soils. Therefore, studies in the future should further strengthen the research on the effect of inhibitors on nitrifying microorganisms and the mechanism of action, especially pay attention to the combination of traditional microbiological methods (such as isolation or enrichment of pure strains) and molecular ecological methods. While strengthening the comparative study of pure culture strain of AOB and AOA, we should investigate deeply the composition of different soil nitrifying microorganisms and their response to nitrifying inhibitors. On this basis, nitrification inhibitors should be optimized or screened. According to the differences of soil physical and chemical characteristics and microbiological characteristics, local conditions should be taken into consideration and appropriate, targeted nitrification inhibitors are selected. The purpose of improving the nitrification inhibition efficiency, reducing nitrogen fertilizer loss and protecting the environment can be achieved.