The Research On The Effects Of Different Nitrogen Fertilizer Amount And Model On Soil Microorganism In Winter Wheat Season

Microorganisms can drive the decomposition and transformation of soil nutrients,affect soilphysical and chemical characteristics and plant health,and play an important role in nutrient cycling and energy flow.This experiment explored the effects of different nitrogen application amounts and fertilization modes on soil microbial diversity,crop production factors and yield of winter wheat.The response mechanism of soil microbial diversity to nitrogen application amount and fertilization mode was explored,in order to find a more scientific and suitable fertilization mode for beneficial microorganism growth.It also hopes to provide a theoretical basis for excavating the great potential of soil microbial resources.The experiment was carried out on the basis of long term localization test for 5 years.The experimental field is located in Sima village of Li Zhuang town,Tongxu County of Henan Province.The planting mode is winter wheat and summer corn rotation.All soil samples involving microbial diversity tests were taken from 2016 to 2017.The experimental wheat seeds were Bainong 207.There were 7 treatments.:?1?CK:0?control?;?2?180 kg/hm² N,base fertilizer at once,L1;?3?270 kg/hm² N,base fertilizer at once,M1;?4?360kg/hm² N,base fertilizer at once,H1;?5?135 kg/hm² N at the beginning and 45 kg/hm² N at grain filling period of wheat,L2;?6?135 kg/hm² N at the beginning and 135 kg/hm² N at jointing stage,M2;?7?180kg/hm² N at the beginning,90 kg/hm² N at jointing stage,and 90 kg/hm² N at grain filling period,H2.In addition,phosphate fertilizer?P₂O₅,90 kg/hm²?and potash fertilizer?K₂O,90 kg/hm²?were imposed before sowing as base fertilizer at the beginning.The irrigation amount of the test is 450 m³/?time·hm²?.The main results are as follows:1.By the analysis of the annotation resolution and complexity of the sample species,we could see that the treatment of high nitrogen application at once had the highest species complexity.Among all the treated samples,the top six of the relative abundance were Proteobacterium,Acidobacteria,Gemmatimonadetes,Chloroflexi,Planctomycetes and Actinomycetes.Moreover,there was no significant change in the relative abundance of the dominant bacteria phylum at different nitrogen levels and different fertilization modes.2.With the advance of wheat growth stage,phased fertilization could improve the diversity of soil bacteria.The bacterial diversity of the treatments of no fertilization and one-off fertilization of high nitrogen application were declining.The bacterial diversity of the high nitrogen application by phased fertilization increased continuously throughout the whole growth period.Considering the whole growing period,the most effective treatment to promote the diversity of bacteria was medium nitrogen application by phased fertilization,followed by the treatment of medium nitrogen application by one-off fertilization under the test conditions of the year.3.Compared with the sowing date,phased fertilization increased the diversity of soil fungi.Fungi are more sensitive to the change in nitrogen fertilizer,and in a certain nitrogen application range,diversity increases with the increase of nitrogen application,and the diversity of low nitrogen fertilizer is increased after the recovery.However,the continuous high nitrogen fertilizer may inhibit the diversity of fungi.The results showed that the amount of nitrogen fertilizer decreased after fertilization..In the whole growth period,the application of phased fertilization at a medium low nitrogen level will bring more complexity to soil fungi than one-off application.Although fertilization has a promoting effect on microbial diversity,fungi are more sensitive to the change in nitrogen application,and in a certain range of nitrogen application,diversity increases with the increase of nitrogen application,but persistent high nitrogen fertilizer may inhibit the diversity of fungi.Therefore,taking into account the sensitivity of fungi to soil nutrient changes,the most effective method to improve the diversity of fungi is the treatment of no fertilization treatment at once,followed by middle nitrogen application in this experiment.4.Correlation analysis between yield factors and yield of wheat showed that there was a very significant positive correlation between the grain number per spike and the yield of wheat.The 1000 grain quality and the number of ears per mu were positively related to the yield.In the sowing period,bacterial diversity and fungal diversity were negatively correlated with crop yield,soil total nitrogen,alkali hydrolysable nitrogen and organic matter content,and the negative correlation between fungal diversity and soil organic matter content reached a significant level.The correlation between bacteria and fungi was positively correlated with seeding time and heading date.And the correlation reached a significant level at heading stage.In the harvest period,there is a negative correlation between the diversity of bacteria and fungi.The yield of winter wheat was positively correlated with the diversity of soil bacteria and fungi at heading stage.5.Under the irrigation level of 450 m³/hm² each time,the most effective method to increased wheat yield was the treatment of high nitrogen application by phased fertilization,followed by the treatment of medium nitrogen application by phased fertilization.The study of this experiment showed that the treatments of phased fertilization had more advantages in increasing wheat yield than fertilization at once among the treatments which have the same amount of nitrogen when the irrigation conditions were suitable.The yield advantage can be achieved by changing the fertilization model which was the same as increasing the amount of nitrogen fertilizer to some extent.For example,the yield of the treatment of medium nitrogen at phased fertilization was significantly higher than that of high and medium nitrogen application at once.From the point of improving the efficiency of fertilizer use,the recommended fertilization treatment was medium nitrogen by phased fertilization.