Effect Of Bio-organic Fertilizer On Phytoremediation Of Heavy Metal Contaminated Soil

With the improvement of the level of industrialization in China,environmental pollution has become increasingly serious,and heavy metal pollution in urban orchards and vegetable fields in urban areas has become increasingly serious.Bio-organic fertilizer is an important fertilizer input for horticultural soils.Whether it has a good effect in repairing heavy metal-contaminated soil is not clear.In this paper,soil samples from mining areas with high concentration of heavy metals were used as research objects.Potted plants were tested by applying bio-organic fertilizers to observe the growth of corn,and then the physical and chemical properties of soil,heavy metal pollution and microbial characteristics were analyzed.Further study on the effect of bio-organic fertilizer on phytoremediation of heavy metal contaminated soil.The main results of this study are as follows:(1)In the corn pot experiment,the plant height,stem diameter,total number of leaves and chlorophyll of the crops treated with bio-organic fertilizer were increased by29.6%～252%,compared with the control group;fresh weight and dry weight of the shoots and fresh weight of roots,the dry weight increased by 3.9 times to 15 times;the absorption of N,P and K increased by 42.1%～252%.Bio-organic fertilizers promote crop growth and increase the utilization of soil nutrients by crops.(2)Compared with the blank control group,the soil available Ni,Cu,and Zn contents in the bio-organic fertilizer and bio-organic fertilizer(sterilization)treatment groups respectively decreased by 94.1% and 92.2%,87.4% and 85.8%,63.8%and 61.9%.The available Pb was not detected(the available Pb content of the blank control group was0.124 mg/kg).Bio-organic fertilizer has a certain passivation and repairing effect on heavy metals in contaminated soil.(3)The enrichment of Pb,As,Cd,Cr,Cu and Zn in the bio-organic fertilizer treatment group increased by 2.1 times to 7.3 times compared with the control group.In the bio-organic fertilizer and bio-organic fertilizer(sterilization)treatment group,the enrichment of Ni in the shoots of the maize plants was higher than that of the roots,and the distribution coefficients in the shoots were 71.1% and 84.6%,respectively.The roots of maize plants absorb a large amount of Pb and As,reflecting the strong enrichment ability of roots to Pb and As.Bio-organic fertilizer can promote the absorption of heavy metals by plants,and plants have certain repairing effects on heavy metal-contaminated soil.(4)The application of bio-organic fertilizer to the acid-poor soil of corn planting significantly increased the p H value of the soil;the organic matter,hydrolyzable nitrogen,available phosphorus and available potassium in the bio-organic fertilizer treatment group were also improved compared with the control group.From 1.9 times to 72.0 times,the N,P,and K contents increased by 40.4% to 131%.Further verification of bio-organic fertilizers increased soil fertility.(5)The application of bio-organic fertilizer increased the abundance of most of the soil genus,changed the soil bacterial community structure,and significantly improved the soil microbial diversity.The bacterial community in the blank control was positively correlated with the available Zn,Pb,Cu and Ni in the soil.The heavy metals in the soil affected the biological and metabolic activities of the microorganisms;the chemical indexes such as p H value,organic matter,hydrolyzable nitrogen,available phosphorus and available potassium.It is positively correlated with the fertilization treatment group and is an important environmental factor for microbial community structure.The growth and development of microorganisms cannot be separated from the supply of soil nutrients.This study pointed out that bio-organic fertilizer increased soil fertility and promoted plant growth,resulting in increased accumulation of heavy metals in plants,as a result of dilution effect,the content of heavy metals in plants decreased,thereby enhancing the resistance of plants in heavy metal contaminated soil.The results of this study provide a basis for enhancing the resistance of horticultural plants to heavy metals by using bio-organic fertilizer in production.