Effects Of Biochar On Soil Organic Carbon Pools And Bacterial Diversity In Black Soil

Biochar is the product of the resource utilization of organic waste.It is widely used as soil improver.In recent years,the destruction and unreasonable utilization of cultivated land by human beings have reduced the organic matter content of black soil and the arable property,which has affected the agricultural production.In this study,corn straw biochar with a mass ratio of 0.5%,1.5%,and 2.5% to soil was applied in black soil with high and low organic matter content in May 2016.The content of soil organic carbon,components,and the structural characteristics and composition of soil bacterial community were determined 28 and 4 0 months after biochar addition.The effect of the interval on the soil organic carbon pool and the diversity of bacterial community at different time periods were studied,as well as the correlation between soil organic carbon components and bacterial community,provide theoretical reference for the improvement of black soil by biochar.The results show that:Biochar significantly increased the total organic carbon content of high and low organic matter soil,and increased with the increase of biochar addition.The effect of 2.5% biochar treatment on the total organic carbon content of soil was the most significant.After 40 months of biochar addition,the increase proportion of biochar on the total organic carbon content of low organic matter soil was higher,increased by 53.0%.Adding biochar can increase the content of soil particulate organic carbon,mineral-bound organic carbon and recombinant organic carbon in black soil with low and high organic matter,and the effect of 2.5% biochar treatment is the most significant.After adding biochar for 40 months,the content of soil total organic carbon decreased,but the content of stable organiac carbon such as soil mineral-bound organic carbon and recombinant organic carbon increased.Biochar improved the stability of soil organic carbon,and had a negative excitation effect on the mineralization of soil organic carbon.After adding biochar for 40 months,the bacterial OTUs of low organic matter soil decreased,and the ? diversity index increased with the increase of biochar addition,first decreased and then increased.Biochar increased the bacteria OTUs and ? diversity index of high organic matter soil.With the increase of the proportion of biochar,it increased first and then decreased.There was significant difference between 0.5% biochar treatment and the control.The OTUs and diversity of bacterial community in high organic matter soil were lower than that in low organic matter soil.On the level of phylum,there are different phylum types in the >1% of the relative abundance of the two kinds of organic matter content black soil.Different phylum types are Firmicutes and Saccharibacteria in the high organic matter soil and Cyanobacteria and Nitrospirae in the low organic matter soil,the dominant bacteria were Proteobacteria,Acidobacteria ?Actinobacteria?Gemmatimonadetes and Chloroflexi in phylum levels.At the class levels,the dominant classes of soil bacteria are Alphaproteobacteria,Gemmatimonadetes,Actinobacteria,Betaproteobacteria and Deltaproteobacteria.1.5% biochar treatment significantly reduced the abundance of Alphaproteobacteria in low organic matter soil,and biochar had no significant effect on m ost of the bacteria.The abundance of dominant bacteria in high organic matter soil was higher than that in low organic matter soil at the level of phylum and class.The correlation analysis of soil organic carbon components and bacterial community showed that the addition of biochar had a certain impact on the diversity and abundance of dominant phylum of bacterial community.In low organic matter soil,there was a significant correlation between the Gemmatimonadetes and soil TOC,MOC and ROC,there was a significant correlation between the d Chloroflexi and soil MOC.There was a significant positive correlation between soil microbial biomass carbon and bacteria Chao1,ACE,and PD?whole?tree index in high organic matter soil.Soil microbial biomass carbon is the main factor affecting the diversity of high organic matter soil.To sum up,adding biochar for a long time increases the content of steady-state organic carbon in the soil,improves the stability of soil organic carbon,reduces the mineralization of s oil organic carbon,enhances the carbon fixation capacity of the soil,improves the organic carbon content of low organic matter black soil,and changes the structure and diversity of bacterial community in the high organic matter black soil.