Secondary Salinization Of Soil In The Vegetable Fields Of Shanghai Suburbs And The Improvement Of S3-1 Strains And Vegetables

In recent years,the secondary salinization of soil has become increasingly serious.A lot of research work has been done at home and abroad on the repair and improvement of the secondary salinization of greenhouses.Among different measures,microbial remediation has the characteristics of low input,high output,high efficiency,and no pollution.This paper has based on the preliminarily survey of the soil conditions in the suburbs of Shanghai and attempted to use related microbes to contribute to the improvement and effective utilization of secondary salinization soil,and at the same time provide a theoretical basis for the development and utilization of secondary salinization soil resources.First,we investigated the soil conditions of the greenhouses in Baoshan District,Pudong New Area,Fengxian District,and Chongming County in some suburban counties in Shanghai.Therefore,it is concluded that Baoshan District belongs to weak saline soil;Pudong New District belongs to strong saline soil and saline soil;Fengxian District belongs to medium saline soil and strong saline soil;Chongming County belongs to medium saline soil,strong saline soil and saline soil.In addition,the soil in most areas is neutral,and the pH value of soil in individual sites is weakly acidic.Moreover,the number of soil microorganisms and the activity of various enzymes vary.Secondly,we selected a plant growth promoting rhizobacteria Bacillus amyloliquefaciens S3-1 as a tested strain to improve the secondary salinized soil.When the soil was irrigated with diluted S3-1 fermented liquid,in the dilution ratio reached 80 and 100 times,the salt content in soil was the lowest and finally decreased by 16.46%.In the field experiment,the salt content of the treated group increased significantly lower than the control group,which was 39.7 % lower than the control group.Soil urease,sucrase and catalase in field experiment showed a trend of continuous increase,with 8.8% higher urease activity and 9.7% higher catalase activity compared to the control group.It shows that S3-1 fermented liquid can improve the secondary salinization of soil and effectively improve soil fertility.At the same time,we studied the salt tolerance of different vegetables and their effects on the improvement of secondary salinized soil.Brassica chinensis,spinach,water spinach,and corn were able to survive in soils containing 4 mL,5 mL,3 mL,and 6 mL of 200 mM NaCl per 10 g of soil.At the same time,spinach,brassica chinensis,water spinach and corn in the pot experiment reduced soil salt content by 34.84%,15.02%,7.87%,and 17.47%,respectively.In the field experiment,spinach,brassica chinensis,and corn were reduced by 55.24% 27.89% and.53.68 % of soil salt content,respectively.With the passage of time,soil urease,sucrose,and catalase activities in the field showed an upward trend.Further,our study found that when brassica chinensis,spinach,water spinach and corn were combined with strains,soil salt content decreased by 16.44%,40.57%,12.82%,and 23.38%,respectively.With the passage of time,the activities of soil sucrase,urease and catalase showed an upward trend,but they were all lower than the control group.At the same time,the combined use resulted in a significant increase in the growth of corn compared to the use of vegetables alone.Meanwhile in order to study the effect of soil improvement on the nutritional status of vegetables,we analyzed the quality of different vegetables under different treatment conditions.The results showed that as for the quality of brassica chinensis,the ascorbic acid content increased by 98.4 %,the soluble protein content increased by 8.5 %,the soluble sugar content increased by 10.1 % and the soluble solids content increased by 15.7 %.For the quality of spinach,the ascorbic acid increased by 38.9 %,soluble protein content increased by 15.5 %,soluble sugar content increased by 16.1 % and soluble solids content decreased by 24.6 %.For the quality of water spinach,soluble protein content increased by 78.6 % and soluble sugar content increased by 26.2 %,but ascorbic acid content and soluble solids content decreased.These results show that the single inoculation of strain S3-1,planting of brassica chinensis,spinach,water spinach and corn,and joint treatment can all reduce soil salinity,effectively alleviate soil secondary salinization,and effectively improve soil physiochemical properties and improve soil fertility.However,when used in combination,the effect is more remarkable,which shows that the combination of the bacteria and the vegetable has an additive effect on the improvement of the secondary salinized soil.Moreover,the results of pot experiments and field trials mutually confirm that S3-1 strain has reduced soil salt content.At the same time,after the soil is improved,the quality of the vegetables can be further improved.Therefore,in the further experiments,we used the S3-1 strain to prepare a secondary salinized soil biological improver.Through experiments,we selected talc as a carrier for S3-1 cells and 1 % sodium carboxymethyl cellulose as a protective agent to develop a soil microbial solid repair agent.