Technical Research On Fly Ash And Bacillus Amyloliquefaciens Improve Plant Nitrogen And Phosphorus Nutrition

Nitrogen（N）and phosphorus（P）are essential nutrient elements for plant growth and development.They play a crucial role in synthesizing various key compounds in plants and also in regulating plant physiological and biochemical processes.The low availability of P in soil is one of the limiting factors for plant growth.Fly ash（FA）is an excellent soil amendment which is rich in nitrate-nitrogen（NO₃^–-N）and P.Proper application of fly ash can significantly increase soil P availability.Plant growth-promoting rhizobacteria（PGPR）are powerful soil microorganisms,and their inoculation into soil can improve the availability of soil N and P.The ecological environment in the contiguous areas of Shanxi,Shaanxi and Inner Mongolia in northwestern China is seriously damaged due to the exploitation of minerals,and the restoration of ecological vegetation in the area is imminent.In order to find the most beneficial soil improvement method for plant growth and improving plant N and P nutrition,we carried out a greenhouse pot experiment by adding fly ash and inoculating Bacillus amyloliquefaciens to Aeolian sandy soil,Pisha Sandstone-amended Aeolian Sandy Soil and Pisha sandstone,using maize and alfalfa as the test plants.The objective of this study was to evaluate the effects of FA and B.amyloliquefaciens on plant growth and N and P nutrition in different soils,and provide a new technical way for land resources utilization and vegetation restoration in the contiguous areas of Shanxi,Shaanxi and Inner Mongolia.The main conclusions are as follows:（1）The responses of maize and alfalfa to FA and B.amyloliquefaciens were different.The addition of FA alone or inoculation with B.amyloliquefaciens,as well as their combination,did not have any significant effect on maize shoot and root dry mass,plant height,or stem diameter.However,it resulted in an increase in alfalfa shoot and root dry mass.The shoot and root mass of alfalfa reached the maximum when combined treatment with FA and B.amyloliquefaciens in the Pisha sandstone,which increased by 362%and203%respectively compared with the treatment without adding FA or B.amyloliquefaciens in the Pisha sandstone;（2）Adding FA and inoculating B.amyloliquefaciens could increase N and P content in plant shoots.The addition of FA alone significantly increased the shoot P content of maize in aeolian sandy soil,which increased by 47%compared with the treatment without adding FA or B.amyloliquefaciens.Inoculation with B.amyloliquefaciens alone significantly increased the shoot N content of maize in Pisha sandstone,by 14%compared with the treatment without adding FA or B.amyloliquefaciens.The addition of FA alone or inoculation with B.amyloliquefaciens,as well as their combination increased the shoot N and P concentration of alfalfa,and the increase was even greater when the two were combined,compared with the treatment without adding FA or B.amyloliquefaciens,the largest increase the shoot P content of reached 86%,and the largest increase the shoot N content of reached 42%;（3）Adding FA and inoculating B.amyloliquefaciens could increase N and P content in soil.Olsen-P concentrations in alfalfa rhizosphere and bulk soil were increased by228–392%and 141–347%after the addition of FA alone or in combination with B.amyloliquefaciens,when compared with the control.In Pisha Sandstone-amended Aeolian Sandy Soil and Pisha sandstone,NH₄⁺-N concentrations in alfalfa rhizosphere and bulk soil were increased 16–36%and 5–49%,NO₃^–-N concentrations in alfalfa rhizosphere and bulk soil were increased 6–35%and 10–94%by inoculating B.amyloliquefaciens alone or in combination with FA;（4）FA addition and B.amyloliquefaciens inoculation altered the structure,diversity,and interaction of soil bacteria communities.The addition of FA alone,or inoculation with B.amyloliquefaciens,or both,increased the relative abundance of Firmicutes while decreasing the relative abundance of Proteobacteria and Acidobacteria.In addition,inoculation with B.amyloliquefaciens increased the relative abundance of Bacillus and Brevibacillus.The addition of FA alone significantly reduced the bacterial community richness and evolution-based diversity in Pisha Sandstone-amended Aeolian sandy soil,the bacterial community diversity in the three soils was significantly reduced by the treatment of B.amyloliquefaciens alone,and the addition of FA and B.amyloliquefaciens significantly reduced the diversity,richness,uniformity and evolution-based diversity in Aeolian sandy soil and Pisha Sandstone-amended Aeolian sandy soil.The correlation network analysis showed that the addition of FA alone,or inoculation with B.amyloliquefaciens,or both,promoted the symbiotic relationship between bacterial communities.In summary,the results of this experiment showed that different plants had different responses to FA and B.amyloliquefaciens.Adding fly ash and B.amyloliquefaciens in soil did not promote the growth of maize or improve the N and P nutrition of maize,but the effects on alfalfa were better.The shoot and root biomass of alfalfa reached the maximum when combined treatment with fly ash and B.amyloliquefaciens in the Pisha sandstone,which could significantly increase the content of N and P in shoots of alfalfa and the concentrations of Olsen-P,NH₄⁺-N and NO₃^–-N in soil.It is recommended to be used in the vegetation restoration in the Pisha sandstone area in Shanxi,Shaanxi and Inner Mongolia.