Preparation Of Compound Functional Bacterial Agent And Its Application In Repairing Atrazine Contaminated Farmland In Situ

Atrazine is the herbicide with the largest amount of corn farmland in the northeast black soil area and the widest application range.Long-term use will cause environmental problems such as soil pollution.At present,bioremediation technology is considered to be the most cost-effective method for atrazine pollution remediation.The effect of simple bioremediation is often affected by many factors such as the environment.At the same time,the traditional polluted soil remediation technology inevitably interferes with agricultural production in the process of remediation,which greatly limits the remediation effect and the feasibility of remediation.In response to the above scientific and practical problems,this study took the team's early screening of Atrazine degrading bacteria Arthrobacter sp.DNS 10 as the key functional strain,and the plant growth promoting strains Enterobacter sp.P1 and Pseudomonas chlororaphis JD37 which had no atrazine degradation function Mix to build a high-efficiency degrading complex flora.On this basis,the optimal construction of microbial inoculants and further discussion on the in-situ remediation effect of the above-mentioned inoculants on atrazine contaminated farmland and the impact on soil physical and chemical properties and corn yields provided a large amount of basic data for later practical application.The main research results of this paper are as follows:Through the antagonism test,it was determined that there was no obvious antagonism relationship between the three strains.Using the shake flask test,it was found that when the initial inoculation ratios of strain DNS 10 and strain P1 were 1:1 and 1:2,the degradation rates of atrazine at 48 h were 99.86%and 99.81%.Compared with DNS10 alone,the degradation rates Increased by 10.75%and 10.71%.The mixed culture of strain DNS 10 and strain JD37 could not significantly increase the rate of decomposition of atrazine by strain DNS 10.The results of the ternary mixed culture showed that when the initial inoculation ratio of DNS10-P1-JD37 was 1:1:0.5,the degradation efficiency of the complex flora for atrazine was significantly higher than that of the strain DNS 10 alone and the strain DNS10-P1 binary compound Cultivation system.Subsequent pot experiments further demonstrated that the compound flora will not negatively affect corn growth.Therefore,the complex flora 1(DNS10-P1)and the complex flora 2(DNS10-P1-JD37)were selected for follow-up experiments.Organic fertilizer,grass charcoal and biochar are used as immobilized carriers of complex flora,and the ratio of carrier materials is optimized by D-optimal ratio.The results show that:the ratio of organic fertilizer,peat and biochar is 73.50%,24.00%,2.50%can be used as an ideal carrier of composite flora 1;the ratio of organic fertilizer,peat and biochar is 63.35%,20.58%,16.07%Can be used as an ideal carrier for complex flora 2.Based on the above optimized carrier ratio,composite functional bacteria agents SP1 and SPI1 were successfully prepared.The degradation rates of the above-mentioned inoculants for atrazine in contaminated soil at 89 days were 89.28%and 86.78%,respectively(dosage:5%,AT:20 mg/kg).In addition,the results of the pot experiment showed that at 21 d,the plant height and plant weight of the corn treated with the fungus SPI1 could be increased by 8.97%and 45.12%compared with the pollution treatment.The key strain DNS 10 colonization of the prepared fungus was investigated by qPCR technology In the circumstances,it was found that at 21 d,the trzN copy number in the soil treated with the fungus SPI1 was 72.13 Copies/mg dry soil,which was 8.39 times and 2.20 times that of the blank treatment(no fungus and atrazine added)and contaminated soil,and Higher than other ratio bacteria.In contrast to the regulation effect of the inoculant on the removal of atrazine in the soil and the growth of corn in the pot experiment,the inoculum SPI1 was selected for subsequent in-situ restoration studies.Bacterial agent SPI1 was used as top dressing to conduct in-situ remediation of farmland.The effects of different dosages of inoculum on the soil remediation of atrazine-contaminated corn farmland and its effects on soil physical and chemical properties and corn yield were investigated.The results showed that the reduction rate of atrazine in the soil was accelerated after the addition of the bacterial agent,and the deceleration rate was increased by 19.30%during the jointing period compared with the treatment without the addition of the bacterial agent.During the restoration process,the addition of inoculants increased the content of alkali-decomposed nitrogen in the crop soil to a certain extent.Among them,the SPI1-10 treatment(the dosage of inoculum SPI1 was 10 kg/mu Treatment)Compared with the treatment without adding bacteria,it increased by 27.57%and 36.97%respectively.The content of available phosphorus in the soil was similar.The content of available phosphorus in the SPI1-10 treatment was increased by 3.54 g/kg and 4.52 g/kg at the jointing stage and harvest period compared with the treatment without the addition of fungi.In addition,the addition of inoculum can promote the growth of corn to a certain extent.The 100-grain weight and yield per mu of SPI1-10 treated corn increased 0.89%and 5.57%compared with the treatment without inoculated inoculum.