Soil Phosphorus Mobilizing Potential And Its Relationship With Functional Microbial Community In Long-term Crop Rotation Soils

Phosphorus is one of the main limiting factors for plant growth and development.The phosphorus content in the soil is high,but only about 5%of the phosphorus can be absorbed and utilized by plants.Activating insoluble phosphorus in soil,increasing soil phosphorus availability,and improving crop utilization of phosphorus in soil are of great significance for the sustainable development of agriculture.Rotation,as a traditional planting method,can significantly improve the effectiveness of soil phosphorus.However,the driving factors for the dissolution of insoluble phosphorus and the activation of soil insoluble phosphorus under different rotation methods are unknown.Therefore,based on long-term positioning experiments,this study selected four soils:wheat continuous cropping,wheat alfalfa rotation,wheat pea rotation,and bare land,and conducted research through indoor cultivation experiments combined with microbial sequencing.Due to the presence of various types of insoluble phosphorus in the soil and the diversity of phosphorus solubilizing microorganisms,this study evaluates the above four soils as a whole.Specifically,this study selected iron phosphate,calcium phosphate,and phytic acid as insoluble phosphorus sources to explore the differences in the dissolution of different insoluble phosphorus by soil phosphorus solubilizing microorganisms under different rotation modes.Among them,iron phosphate and calcium phosphate are typical insoluble inorganic phosphorus in soil,while phytic acid is typical insoluble organic phosphorus in soil.Three aspects of research were conducted through the above experiments:the impact of long-term rotation on soil microbial activity;The impact of long-term rotation on soil phosphorus solubility potential;The composition of phosphorus solubilizing microbial community and its relationship with phosphorus solubilizing potential.To explore the composition,activity,and potential characteristics of phosphorus solubilizing microbial communities in long-term rotation soil.The main research results are as follows:（1）Long term rotation improved soil nutrient conditions,increased soil microbial biomass phosphorus and phosphatase activity.The alkaline phosphatase activity in wheat alfalfa and wheat pea rotation soils increased by 10%and 15%,respectively,compared to wheat continuous cropping soils;Moreover,the microbial biomass phosphorus,total nitrogen and total phosphorus content in wheat pea rotation soil were significantly higher than those in wheat continuous cropping soil.（2）The soil respiration of different rotation crops was significantly affected by the addition of carbon and nitrogen sources,and the cumulative soil respiration of different rotation crops was different.The cumulative release of soil carbon dioxide reached its maximum under the addition of C5N100(5g C kg^-1,100mg N kg^-1)nutrients.This indicates that the activity of soil microorganisms is influenced by the addition of soil carbon and nitrogen sources.As the amount of carbon source added increases,the activity of microorganisms gradually increases,while as the amount of nitrogen source added increases,the activity of microorganisms first increases and then remains unchanged.（3）The phosphorus activation potential of iron phosphate treatment is the highest among the four types of soil,among which the phosphorus activation potential of wheat alfalfa rotation soil treated with iron phosphate addition is 6.95mg P kg^-1,and the phosphorus activation potential of wheat pea rotation is 5.87 mg P kg^-1,which are 1.7and 1.4 times that of wheat continuous cropping,respectively.In addition,the phosphorus activation potential of the four soils is as follows:iron phosphate addition>phytic acid addition>calcium phosphate addition>control.（4）Compared with wheat monoculture,alfalfa,pea and wheat rotation significantly reduced the average relative abundance of Burkholderiaceae,while the average relative abundance of Bradyrhizobiaceae was significantly increased.The average enrichment of Bradyrhizobiaceae in wheat pea rotation,wheat alfalfa rotation soil was 65%and 27%,respectively,which was 60%and 22%higher than that in wheat continuous cropping soil.Research has found that crop rotation significantly increases soil phosphorus solubilization potential,which is correlated with the number of functional genes of soil phosphorus solubilizing microorganisms,providing a theoretical basis for optimizing nutrient management in farmland.