| Heavy metal pollution in farmland soil is increasingly serious,and the problem of cadmium pollution is the most serious of farmland heavy metal pollution.Biochar and water management play an important role in the restoration of heavy metal pollution and rice cultivation.In this study,paddy soil was selected as the research object,and silkworm charcoal(BC)and silkworm(OM)were used as research materials to carry out rice pot experiment to explore the combined effects of silkworm charcoal,silkworm sand and water on microbial ecology in Cd-contaminated soil.And the effect of Cd absorption and accumulation on rice provides a scientific basis for the study of bio-charcoal and its raw materials and water on the remediation of heavy metal pollution and its mechanism.Below are key research findings:1)At different periods of rice growth and in contrast to blanks,both BC and OM significantly reduced soil respiration efficiency and soil phosphatase activity(P<0.05),but increased soil catalase activity and soil urease under both water management methods.active.For the same treatment,there was no significant difference in soil respiration and soil enzyme activity between"thin-light wet-sun" and "wet-wet alternating".Among them,soil respiration decreased by 0.10 L/g/h at the tillering stage,which was the greatest decrease.The BC treatment in the thin-shallow-moisture harvest period was lower than that in the harvest period,which was decreased by 0.07 L/g/h;the soil phosphatase in the BC treatment was decreased.The decrease in activity was significantly greater than that of OM treatment.Among them,the reduction in BC treatment was 5.61-9.73 ?g/g,and the decrease in OM treatment was:0.04-7.53 ?g/g.The increase in CAT treatment of soil catalase activity was significantly greater than that of OM treatment.Among them,the activity of catalase increased by 0.23 ml/g under BC treatment during the thin-shallow-wet harvesting period;during the harvest period,the increase of urease in BC treatment was more obvious than that of OM treatment,and the BC treatment under "thin-light-wet-sun" increased.4.72 mg/g,the most significant effect.2)Soil microbes had little effect on the carbon source utilization under different water management.The application of BC and OM inhibited and promoted the microbial community's metabolic activity.The dominant communities of soil microbes were amino acids,esters and amines.Water management has a significant effect on Shannon's diversity index H',richness index S,and McIntosh index U,but it has no significant effect on the evenness index E and the Simponon index D.BC treatment is beneficial to improve Shannon's diversity index H' and richness index S.3)Water management had no significant effect on soil pH.Compared with CK,BC and OM could increase soil pH after BC,OM>CK.Different treatments all reduced the content of available Cd in rice soil.Compared with CK,the application of BC under the "thin,shallow and moist sun" had the best reduction effect on the content of available Cd in soil,which was reduced by 51.14%.The accumulation of Cd in different parts of the same rice was performed as follows:root>culm sheath>brown rice,among which,the cumulative Cd of "thin,shallow and wet sun" was lower than that of "dry and wet alternation";the effect of different treatments on the same water management was CK>OM>BC,in which the Cd content of BC-treated brown rice under the "thin-light-wet-sun" reduction was 52.59%lower than that of CK,and had the best effect.Based on the above results,the application of BC treatment under the water management of thin,light and moist sun enhanced the activities of soil catalase and urease,promoted the use of carbon sources by soil microorganisms,increased soil pH,and effectively reduced soil efficiency.The level of Cd had the lowest accumulation of Cd in rice,and had the best resistance to Cd. |
PDF Full Text Request