Effects Of Biochar On Soil Environment And Safety Evaluation

Biochar has important research significance in improving soil fertility,raising soil pH and protecting soil ecological security.In order to investigate the safety of biochar to the soil environment,this paper uses sludge,lotus stalk and peanut shell as raw materials to prepare biochar at 450 ?,550 ?,650 ? and 750 ?.The experiment selected Xiqing District of Tianjin The farmland soil beside the Duoliushe River was taken as the research object.It was added to the soil at different concentration ratios(0%,2%,4%,6%,10%,and 20%),and its physical and chemical properties on the soil were systematically studied.Microbial species,seed germination,and effects on soil ecological security.The results obtained are as follows:(1)With the increase of pyrolysis temperature,the yield,hydrogen,oxygen and nitrogen content of the three biochars decreased significantly,while the carbon content,pH and ash content of the three biochars increased significantly.By studying the changes of soil pH,organic matter,cation exchange capacity,and catalase under the action of biochar and its action mechanism.The results showed that: sludge,lotus stalk and peanut shell carbon significantly increased the pH,CEC and organic matter content of the tested soil,the increase ranges were 0.92 to 1.11,8.62 to 9.86 cmol / kg,32.41 to 38.31 g / kg;0.64 to 0.76 13.13 to 16.15 cmol / kg,37.98 to 46.90 g / kg;0.56 to 0.72,10.38 to 11.51 cmol / kg,16.41 to 19.04 g / kg.Among them,the effect of adding different types of biochar at the same temperature was 6% with sludge charcoal,10% with lotus charcoal,and 6% with peanut shell char.(2)Analyze the change of microbial community by measuring the soil bacterial community.The results showed that,through soil microbial high-throughput sequencing analysis,10 dominant phylums were found.After the application of biochar,the contents of Planctomycetes,Nocardioides,and Proteobacteria increased,and glucose and lactose produced by fermentation increased,which increased nutrients in the soil.(Aeromicrobium)and Pseudomonas(Pseudomonas)content decreased,the utilization rate of soil organic carbides decreased,and to some extent affected soil quality.(3)The effects of sludge charcoal,lotus root charcoal,and peanut shell charcoal on the soybean germination were investigated through pot experiments,with different additions(0%,2%,4%,6%,10%,and 20%),and Find out the safe range of the amount of biochar added.The results showed that the application of biochar increased the germination rate of soybeans,and the increase rates were 4.2 to 23.6%,4.2 to 23.6%,and 5.56 to 19.4%,respectively.Among them,by comparing the three types of biochars,it can be concluded that the pyrolysis temperature is 650 ? and the sludge charcoal is added at a concentration of 6%,the pyrolysis temperature is 550 ? and the lotus stem charcoal is added at a concentration of 10%.The pyrolysis temperature is 650 ? Adding 6% and 10% lotus stalk charcoal and pyrolysis temperature 650 ? and 6% peanut shell charcoal added to the test soil found that the germination time of the seeds was shortened and the germination rate was increased,indicating that in these types Under these conditions,the safety risks of biochar to the soil environment are relatively low.But removing these several addition schemes,biochar has a significant inhibitory effect on seed germination and poses a certain safety risk to the soil environment.(4)In this paper,the analytic hierarchy process is used to evaluate the significance of biochar on soil ecological security by combining the two aspects of soybean germination rate and soil microbial richness.It can be known that the weight combination of the nutrient balance in the soil is the highest,and it is an object that needs to be guarded against in the entire risk system analysis.