The Study On Nitrification Inhibitor Evaluation Method And Novel Amended Nitrification Inhibitor Synthesis And Application

Nitrification inhibitors(NI)have become one of the important measures to nitrogenous fertilizer enhancement because of their activity of prolonging and improving the efficiency of nitrogenous fertilizer environmentally friendly.With the extension of NI application,it is urgent to evaluate and further improve them reasonably.This study raised the systematic accurate test methods of NI evaluation which contained: the model by ammonia oxidation bacteria(AOB)strains bacteriostatic experiment,constant temperature soil culture experiment,greenhouse pot experiment and field experiment,to research the effect of NI in vitro environment,soil environment and crop cultivation environment of ammonia oxidizing bacteria inhibition.As well as,the effect of this inhibition on soil nitrogen fertilizer conversion and crop yield increase was discussed,and the feasibility of the evaluation method was verified.At the same time,as the improved 3,4-dimethylpyrazole phosphate(DMPP),zinc coordination of 3,4-dimethylpyrazole phosphate(DMS)was prepared.And the actual effect of DMS was evaluated in subsequent studies with DMPP and dicyandiamide(DCD)used as the standard.The main results of the research are as follows:(1)The bacteriostatic effect of DMPP,DCD and 2-chloro-6-trichloromethylpyridine(NP)was evaluated using model strain of ammonia-oxidizing bacteria.The results showed that DMPP and NP had better effect than DCD,and could effectively inhibit the growth of bacteria at 0.1% concentration,while 10% DCD could achieve acceptable effect.Compared with DMPP,the bacteriostatic effect of NP decreased rapidly with the concentration decreasing,and its nitrification inhibition rate of 0.05% was at the same level as that of 0.025%DMPP.After comprehensive evaluation,DMPP has the most stable effect and could inhibit the growth of ammonia-oxidizing bacteria at low concentration.This experiment can effectively and rapidly evaluate the actual bacteriostatic effect of nitrifying inhibitors,and provide theoretical basis for practical application.(2)The abundance of AOB and Ammonia-oxidizing archaea(AOA)in soil was determined by RT-PCR for amo A gene.This method can effectively detect the abundance of AOB in different soils and provide an effective means for evaluating the bacteriostatic effect of NI.Soil culture experiments were conducted to detect the nitrification inhibition effect of DMPP in different soil sampled locations in the same geographical area,and it was found that the nitrification inhibition effect of DMPP was positively correlated with its bacteriostatic efficiency.Compared with the nitrification inhibition rate,the bacteriostatic effect of soil NI is the main factor to determine the nitrification inhibition effect,and is an important evaluation index of this evaluation method.(3)In this experiment,an improved DMPP,DMS of was prepared,which was slightly soluble in water,had better stability in fertilizer,and existed longer in soil,which could improve the nitrification inhibition effect.In vitro ammonia-oxidizing bacteria inhibition test verified that DMS had the same antibacterial ability as DMPP.(4)This experiment took DMPP and DCD as the objects to verify the effects of DMS on thermostatic culture and crop pot experiment in two different AOB and AOA soils.The results showed that AOA had no significant response to nitrogen and NI,indicating that AOA had little effect on soil nitrification in the tested soils.On brown loam,the nitrifying inhibitors had no obvious effect on nitrogen fertilizer and crop yield increase,while on black soil,the effect was opposite.The main reason for this difference was the difference in the abundance of AOB in the soil: The abundance of AOB in brown loam is only 1/10 of that in black soil,and AOB cannot play a major role in the process of soil nitrogen transformation,resulting in no significant increase in soil nitrogen content even if AOB is inhibited.Therefore,the selection of suitable soil with high AOB abundance in the experimental system is the key to the success of verification.(5)On black soil,the effect of DMS was better than that of DMPP and DCD,which significantly improved the utilization rate of nitrogen fertilizer and crop yield.Moreover,its growth promoting effect was more obvious in the middle and later stages of the experiment,indicating that DMS has the advantage of long-term effect compared with DMPP.In the field experiment of the same black soil,DMS had a better yield increase effect than DMPP,and the optimal supplemental level was 1% of nitrogen application rate,and the lowest effective supplemental level was 0.5% of nitrogen application rate.