Effects Of Earthworms On The Properties Of Biochar

In recent years,as an important carbonaceous material,biochar has received more and more attention due to its low production cost,environmental friendliness,and good improvement effect.Earthworms,as one of the most abundant animal groups in the soil,can stimulate the proliferation of microorganisms through continuous burrowing and feeding activities,and trigger changes in the microbial community,leading to the decomposition of soil organic matter and nutrient cycling,thereby changing the physical and chemical properties and biological properties of the soil.Earthworms,a "soil engineer",and biochars with various functions and broad application prospects have complex interactions in the soil environment.In this study,the effects of earthworms and earthworm mucus on the physical and chemical properties of biochar and soils were investigated using biochar-earthworm,biochar-earthworm mucus,and soil-biochar-earthworm culture systems.Effects of feeding and intestinal feeding of earthworms on the properties of biochar under cultivation conditions.Research indicates:(1)Compared with the control group,the p H and CEC of biochar decreased significantly after the addition of earthworms,and the organic carbon content increased significantly.This shows that earthworms have the potential to change the charcoal properties of biochar.(2)Earthworm mucus increased the nitrate nitrogen content of biochar,reduced the amount of cation exchange,and did not significantly affect the p H,available phosphorus,and organic carbon content.This indicates that the mucus action of earthworms is a possible way to change biochar.(3)In the soil culture system,the content of available phosphorus in vermicompost S and vermicompost SB added with biochar soil were significantly increased compared with those in which no earthworm was added(P<0.05).Moreover,in SB,the content of available phosphorus in vermicompost was also significantly increased compared with the soil inoculated with vermicompost,while the content of vermicompost in soil S did not change significantly.Compared with soil S,soils without earthworms and soils inoculated with earthworms had significantly higher ammonium nitrogen content,while soil SB had significantly higher ammonium nitrogen content than soil S.It is inferred that the feeding-intestinal effect of earthworms increased the effective phosphorus content of biochar and reduced the ammonium nitrogen content.(4)The alkaline phosphatase activity value in soil S vermicompost was significantly lower than that in the earth without earthworm and the soil cultivated with earthworm,while the phosphatase activity in the soil SB vermicompost was only significantly lower than that of the soil cultivated with earthworm.It shows that the effect of earthworm feeding through the intestine has an effect on the activity of biochar on soil alkaline phosphatase.The invertase activity value of soil S vermicompost increased significantly compared to the soil without earthworms,and decreased significantly compared to the soil cultivated with earthworm;but the sucrase activity in soil SB vermicompost only increased significantly compared to the non-earthworm soil,Indicating that the effect of earthworm feeding through the intestine has an effect on the activity of biochar on soil invertase activity.(5)The five dominant bacterial groups(Proteobacteria,Actinomycetes,Bacteroidetes,Green Campylobacter,and Acidobacteria)all changed significantly in comparison with S0 and SE at the phylum level.The trend of SBC compared to SB0 and SBE is the same as SC compared to S0 and SE,but the magnitude of change is smaller than SC.Compared with SC,the relative abundance of Proteobacteria,Campylobacter phylum and Acidobacteria phylum increased,while Actinomycetes and Bacteroidetes decreased.It shows that the feeding of earthworms and the special environment in the intestine may change the structure and function of biochar,which in turn changes the diversity,abundance and relative abundance of the bacterial flora in the excrement of earthworm feces.This also shows that the effect of earthworm feeding through the intestine is another possible way to change the properties of biochar.In summary,earthworms can change the physicochemical properties and biological properties of biochar through ingestion and secretion of mucus.This provides a basis for understanding the interaction between biochar,earthworms,and even soil organisms.