Effect Of Biochar On Bacillus Mucilaginosus And Bacillus Megaterium Activity And Mechanism Of Phosphate Solubilizing

The utilization rate of phosphate fertilizer in the current season in china is only 10% to20%,and long-term excessive application of phosphate fertilizer causes a large accumulation of phosphorus in soil and forms a certain environmental risk.Phosphorous solubilizing microorganisms in soil can convert insoluble phosphorus into soluble phosphorus,which is of great significance to the use of phosphorus in soil.Biochar not only contains a certain amount of phosphorus,but also has physical and chemical characteristics such as loose porosity and large specific surface area,which may promote the growth of microorganisms.Excavation and utilization of the positive interaction between biochar and phosphorous solubilizing microorganisms may become one of feasible way to activate phosphorus and reduce phosphate fertilizer input.Therefore,this study have two strains of phosphorous solubilizing microorganisms with have potential application?Bacillus Mucilaginosus 19749,Bacillus Megaterium 1.234?and two kinds of biochar?rice straw biochar,rice husk biochar?as test materials,by adding the amount of biochar treatment,cultivating system of p H treatment,biochar leacheates treatment,rice seedling culture and other laboratory test.In view of the amount of biochar addition on phosphate solubilizing effect of phosphorous solubilizing microorganisms,the effect of biochar on the mechanism of phosphorous solubilizing microorganism under the optimum amount of condition,the influence of biochar and the phosphorous solubilizing microorganism compound on rice seedling growth and development and impact on phosphorus absorption problems such as research on the system,in order to deepen the understanding the interaction of biochar-phosphorous solubilizing microorganism and explore the compound effect on application of biochar-phosphorous solubilizing microorganism.The main research results are as follows:1.Liquid culture insoluble Ca₃?PO₄?₂ medium,when the initial p H was alkaline,the addition of rice straw biochar and rice husk biochar can effectively improve the hydrolysis ability of bacillus mucilaginosus and bacillus megaterium to Ca₃?PO₄?₂.As the amount of biochar added increases,soluble phosphorus content in culture medium increased gradually.Among them,under the condition of 1.5%?mass ratio?addition,rice straw biochar treatment increased the soluble phosphorus content in the culture medium of bacillus mucilaginosus and bacillus megaterium by 87.93% and 62% compared with the control treatment;the solublephosphorus content of rice husk biochar treatment increased by 265.52% and 54.98%compared with the control treatment.The effect of adding 1.5% rice straw biochar on the effect of phosphate solubilizing was significantly higher than that of rice husk biochar.2.Liquid culture insoluble Ca₃?PO₄?₂ medium,when the initial p H was neutral,the addition of 1.5%?mass ratio?biochar can effectively improve the phosphorous solubilizing ability of bacillus mucilaginosus and bacillus megaterium,which is better than that of alkaline system.Among them,under the condition of 1.5% addition,the soluble phosphorus content in the culture medium of bacillus mucilaginosus and bacillus megaterium by 181.66%and 76.31% in rice straw biochar treatment compared with the control treatment;the soluble phosphorus content of rice husk biochar treatment was increased by 707.30% and 1492.44%compared with the control treatment.It shows that p H is one of the important factors that affect the activity of phosphorous solubilization with phosphorous solubilizing microorganism.In addition,the phosphatase activity in the culture medium increased significantly.and the types of organic acids produced were not changed,but the content increased significantly.Biochar promotes phosphatase secrection by phosphorous solubilizing microorganism secretion and enhance the ability to decompose Ca₃?PO₄?₂ in the process of phosphorous solubilization,thus dissolving insoluble phosphate and increasing soluble phosphorus content.3.Rice straw biochar leacheates and rice husk biochar leacheates significantly increased the soluble phosphorus content in the culture medium of phosphorous solubilizing microorganism,But the effect was weaker than that of biochar treatment,indicating that under this experimental system,the growth and activity of phosphorous solubilizing microorganism were mainly affected by the physicochemical properties of biochar,supplemented by the role of water-soluble components of biochar.4.The compound of rice straw biochar with bacillus mucilaginosus and bacillus megaterium was added to the culture medium,and both significantly promoted the growth of rice seedlings and root morphology,significantly increased the total root length,projected area,total surface area of root,total root volume,root tips,forks and crossings,increased fresh and dry weight of rice plants,in the later period of cultivation,also promoted rice plant height as well as significantly increased the total phosphorus content.After 20 days of culture,the total phosphorus content of rice straw biochar compound of bacillus mucilaginosus and bacillus megaterium reached 7.49g·kg^-1?7.01g·kg^-1 for rice plants;the amount of bacillus mucilaginosus and bacillus megaterium in rice straw biochar increased by 27.5% and 9.5%compared with that before culture.In summary,under the conditions of this test,biochar can promote the secretion of phosphatase by phosphorous solubilizing microorganism and increase the organic acids content in the culture system,thereby enhancing the effect of phosphorous solubilizing and promoting the growth of rice seedlings.The effect of adding 1.5% rice straw biochar is the most effective.