Effects Of Warming And Straw Application On Soil Microbial Community In A Soybean-Winter Wheat Rotation Cropland

In order to understand the adaptability of farmland soil microorganism to temperature and straw decomposition under the background of global warming and straw resource waste,based on the experiment conducted in Nanjing experimental field.An infrared warming lamp was set up to increase the temperature for 24 hours,and the straw of the last long season was left as the biochar of the next growth season.During the most vigorous growth period of each season,chloroform fumigation was used to test microbial biomass carbon and nitrogen,and high-throughput sequencing was used to test microbial gene sequence.It provides a reference for improving the model of soil microbe change in farmland ecosystem under the condition of climate warming and straw resources utilization.Based on the data analysis of two years,conclusions is following:1.The effect of warming and straw application on soil microbial biomass carbon and nitrogen(MBC,MBN)was not significant in the same growth season(P>0.05),but the difference was significant in different growth seasons(P<0.05).The soil MBC / MBN ratio increased with the warming.The soil MBC and MBN decreased with combine warming and the straw application,but there was no significant difference(P > 0.05)in winter wheat and soybean seasons.Soil microbial biomass was affected by different crop types.2.The effect of warming and straw application did not significantly change the abundance of dominant bacteria in each growth season(P>0.05),but increased the similarity of the composition of dominant bacteria.The dominant bacteria were Proteobacteria,which accounted for more than 20% in winter wheat and 40% in soybean.The warming and straw application reduced the abundance of Proteobacteria in the soil of winter wheat season and increased the abundance of soybean season.The effect of straw application on the composition and clustering of soil bacteria was greater than that of warming.The dominant fungi were Ascomycota and Basidiomycota.The abundance of Ascomycota in winter wheat was less than that in soybean,and there was no significant difference in warming and straw application(P>0.05).The effect of long-term warming and straw application on the structure of soil microbial community is directional,and the similarity of dominant bacterial groups ineach growth season is improved at the level of Class,Order,Family and Genus.3.The change of ?-diversity of soil bacteria and fungi in different growth seasons was not significant(P>0.05).The index of soil bacteria increased in the last three growth seasons,which indicated that long-term warming and straw application could improve the richness and diversity of soil bacteria.Warming changed the effect of straw application on bacterial diversity,while had no effect in fungal diversity with straw application.The correlation between soil MBC and MBN and ?-diversity of bacteria and fungi was not significant(P>0.05).There were significant correlations between ?-diversity indexs of soil bacteria(P<0.05),and positive correlations between species and Shannon,Simpson and MBC.Long term warming and straw application could improve the correlation between soil MBC and MBN and bacterial ?-diversity.There was a significant positive correlation between Shannon index and Simpson index(P<0.05),and there was a significant positive correlation between Chao1 index and species(P<0.05).The correlation between the Chao1,species and MBC and MBN in winter wheat season was lower than that in soybean season.The results of bacterial PCo A analysis showed that the explanations of PC1 in the later three seasons were higher than54%,which could explain the difference between samples well,and the short distance between samples with different straw amount showed that straw amount was not the main reason for the difference.The results of PCo A analysis showed that the total interpretation of PC1 and PC2 was more than 42%,and the difference of clustering distance was reduced,indicating that the effect of warming and straw application on the difference of soil fungal composition was weakened.4.According to UPGMA cluster analysis and PICRUSt2 analysis,the function of soil bacteria was predicted that long-term warming and straw application had put the selectivity to soil bacteria,and the relationship between the microbes adapted to the environment was relatively close.The function of bacteria in soil changed from environmental information processing to metabolism,espeically amino acid metabolism and carbohydrate metabolism.The UPGMA cluster analysis of soil fungi showed that straw was the main factor affecting the relationship of fungi on the level of Phylum.It was found that saprophytic and undefined vegetative types were dominant in each growth season by analyzing the function of fungi with software fuguild.Further dividing the functional groups of fungi,we found that the abundanceof plant pathogenic and parasitic fungi decreased,which indicated that the time of warming and straw application had a guiding role in the function of soil fungi.