Abstract:

Objective: This study aims to investigate the effects of biochar and its aging biochar on the soil main nutrient content and microbial community composition in Chinese fir plantation,and to provide a reasonable selection basis for the use of biochar in Chinese fir plantation in southern China. Method: Chinese fir leaves were used as raw materials to make biochar and the biochar was washed and acidified to simulate the long-term aging in the natural environment of southern China. The red soil in the second generation Cunninghamia lanceolata forest was collected as the experimental soil. Four groups treatments were set up,including no biochar(CK),3% biochar (BC),3% washed aged biochar (WBC),and 3% acidified aged biochar (OBC) added in the soil. After 150 days of indoor cultivation,the main soil nutrients were determined. At the same time,the high-throughput sequencing technology was used to analyze the community composition of soil bacteria and fungi. The correlation between the content of soil main nutrients and the relative abundance of main microorganisms was further analyzed. Result: The addition of biochar can significantly increase the content of total carbon,total nitrogen,dissolved organic carbon,available potassium and nitrate in soil. Aged biochar reduced the content of dissolved organic carbon. OBC also had a significant inhibitory effect on the content of dissolved organic nitrogen(P < 0.05). Venn diagram analysis showed that OBC had the most obvious promotion effect on soil microbial richness. Biochar and aged biochar had a promoting effect on the relative abundance of Proteobacteria,Gemmatimonadetes,Bacteroidetes,Gemmatimonadaceae,Sphingomonadaceae and Rhodospirillaceae. OBC significantly increased the relative abundance of Verrucomicrobia and Planctomycetes. Chloroflexi,Actinobacteria and Firmicutes were significantly negatively correlated with total carbon and total nitrogen,while Proteobacteria and Bacteroidetes were significantly positively correlated with available potassium and nitrate nitrogen. As for fungi,Ascomycota and Basidiomycota were the dominant phyla. WBC increased the relative abundance of Basidiomycota,Mucoromycota and Ganodermataceae. OBC reduced the relative abundance of Chytridiomycota. Ascomycota were significantly positively correlated with ammonium nitrogen and dissolved organic carbon,and the relative abundance of the Mortierellomycota was significantly positively correlated with dissolved organic nitrogen. Conclusion: Biochar can effectively improve the soil main nutrients content of Cunninghamia lanceolata plantation. However,the effect of biochar on soil nutrient improvement is weakened after washing and acidification. Biochar and aged biochar can increase the abundance of microorganisms in general,but there are differences in the regulation of relative abundance of main microbial groups.

Key words: biochar, aging treatment, soil nutrients, high-throughput sequencing, microbial