Preparation Of Soil Microorganisms And Biopolymer Materials And Their Role In The Improvement Of Saline-Alkali Land

With the growth of global population,the contradiction between man and land is increasingly prominent.Soil salinization,as one of the main causes of farmland degradation,has become a global ecological problem.The Yellow River delta is an important reserve land resource in China,but nearly half of the land in this region has different degree of salinization,which seriously affects the growth of crops.although there are many ways to improve the saline-alkali land,such as water conservancy project,planting transformation.However,the effect was not obvious.Therefore,it is promising to develop widely applicable and easy operate products to solve the saline-alkali land problem.Frist we screened probiotics strains with tolerance to hyperosmotic stress from saline soil.By simulating the soil column experiment to optimize its ratio,the best water retention agent formula was screened and obtained,combined with probiotics to form saline-alkali land special improver;And then choose experimental area in the Yellow River delta?binzhou?national agricultural science and technology park to select experimental area,to carry out a six-month?November 23,2018-June 4,2019?the effects of the analysis.We measured the variation of soil salinity under different modifier dosage,different salt content and different soil depth.We also measured the yield of wheat and selected samples with good effect to analyze the changes of soil flora structure.The conclusions are the following:?1?Screening of salt-tolerant microorganismsWe isolated 21 salt-tolerant strains from 20 salinized soils and analyzed their salt-tolerant capacity.The results showed that 15 strains could tolerate 5%salt and 6 strains could tolerate 10%salt.We carried out phylogenetic identification of the strain which was able to tolerate 10%salt,and the results showed there were Bacillus amyloliquefaciens,Bacillus licheniformis,Bacillus subtilis,Bacillus subtilis and Bacillus safensis.Bacillus subtilis strain was selected for liquid fermentation,and then salt-resistant probiotics were prepared,so that the liquid fermentation level reached 1x10¹⁰cfu/ml.?2?Optimized the ratio of improver in soil column simulation experimentThe polyglutamic acid fermentation broth and alginolytic extracts were combined in5 ratios of 1:1,3:7,7:3,0:1 and 1:0.We designed soil column simulation experiments to analyze the effects of different modifiers on salt migration.Experimental conditions as follows:the soil column 60 cm high,14 cm in diameter,the concentration of salt solution for 3 g/L Na Cl,improver added amount for 6 g,250W infrared distance 20 cm bulb light,determine surface soil salinity every 6 hours for 130 hours,the results showed that The best ratio of polyglutamic acid and seaweed extract was 1:1,the salt content of surface soil was 28.5%lower than the control group,total moisture evaporation decreased by17.3%.?3?Field effect analysis of the effects of biopolymer improvers on salt migrationAccording to the optimized ratio,seaweed polyglutamic acid compound improv was prepared,and salt-resistant probiotics were added to 5x105 cfu/m L to prepare experimental samples needed in the field.Choose three different salt content of the test area,four plots per test area,each 20 m x 20 m,then each field is divided into 10 m x 4of 10 m,design 0,50 per kg,100 kg,200 kg,4 content conditions to carry out the field water resistance salt effect analysis,The time of the first experiment is on November 23,2018,Samples were taken at 5 time points on the 48th,96th,144th and 193rd days.We measured the thickness of the sampled soil from 0 to 15 cm and from 15 to 30 cm at a time,Then we measured the electrical conductivity of each soil sample and converted its salt content.The results showed that in the experiment period,the soil salinity in the mildly saline-alkali land was the best under the condition of medium dosage of improv,the increase of soil salinity was significantly reduced,and the salt control effect was 42.73%higher than the control group.?4?Effects of biopolymer improvers on wheat yieldIn this paper,the promotion effect of biopolymer improveron on crop growth was further analyzed.The plant height and yield of the selected experimental plot planted with the crop variety Jimai 20 were measured in early June.The results showed that the wheat plant height in mild saline-alkali land increased by 15.9%,the plant height of moderate saline-alkali land increased by 17.2%.And the measured yield was increased by 9.38%in mild saline-alkali land and 15.69%in moderate saline-alkali land.The results showed that the improver could improve the growth state and yield of crops.?5?Effects of biopolymer improvers on changes in soil flora structureThe effects of biopolymer modifiers on the microbial flora structure in saline-alkali soils were also analyzed.Compared with the control group,the bacterial chao1 index of surface soil increased by 4.6%and Shannon index increased by 0.8%.Fungal chao1 index and Shannon index of surface soil increased by 13.2%and 31.2%respectively.Bacterial chao1 index in deep soil decreased by 13.8%and Shannon index decreased by 3.8%.Fungal chao1 index in deep soil decreased by 28.8%and Shannon index decreased by7.3%.Therefore,the?diversity of surface soil bacteria and fungi increased significantly,while the deep soil bacteria and fungi?diversity decreased significantly.The changes of?bacterial diversity was significant,while there was no significant change in fungal?diversity.The results showed that the use of improvers could significantly increase the diversity of soil microorganisms.