Effect Of Organic Materials And Phosphorus-dissolving Bacteria On Adsorption Characteristics And Availability Of Phosphorus In Mollisols

Mollisols is a valuable natural resource,it plays an essential role in China's important grain production.However,due to the continuous cropping of corn for several dec ades,the farming methods and the types of fertilization are single,consequently increasing soil degradation.Phosphorus is easily fixed,reducing its mobility in the soil,l and the efficiency of phosphate fertilizer has been low.The application of biochar and organic fertilizer is an important alternative means to fertilize the soil and enhance fertility.The functional groups of soil organic matter and organic acids can affect the adsorption of phosphorus.To this end,this research focused on farmland Mollisols,and studies the effects of biochar and organic fertilizer on the adsorption characteristics and availability of phosphorus.This studyl provide s a theoretical basis for the application of biochar and organic fertilizer in fertilized Mollisols and the regulation of its phosphorus conversion.The experiment was conducted in two stages.First,biochar and organic fertilizer were added to the experimental soil to assess its effect on soil phosphorus adsorption and desorption.Three levels of biochar and organic fertilizer at mass ratio was 1%,2%,and 3%,were mixed with Mollisols,and incubated at 25°C for 45 days.The second experiment included phosphate-dissolving bacteria,biochar and organic fertilizer with the same leve ls as above.The second experiment was done to study the interactive effects biochar,organic fertilizer and the phosphate-dissolving bacteria had on the bioavailability and utilization of soil phosphorus.In the tested Mollisols,3% biochar,3% organic fertilizer,3% biochar with phosphate-dissolving,3% organic fertilizer with phosphate-dissolving bacteria,and the soybean pot experiment was carried out for 40 days.The biochar used in the test was provided by Shenyang Biochar Engineering Technology Research Center.Bio-organic fertilizer is provided by Runong Technology Co.,Ltd.,Wuchang City,Heilongjiang Province.The test results are as follows:?1?With the increase of biochar and organic fertilizer and the prolongation of culture time,the amount of phosphorus adsorbed by soil decreased gradually.The phosphorus adsorption capacity of soil treated with organic fertilizer was lower than that of b iochar,and the desorption of soil phosphorus by high level organic fertilizer treatment phenomenon.The phosphorus adsorption adsorption capacity of different levels of biochar culture for 15 days was 7.65 mg.g^-1,6.65 mg.g^-1,4.03 mg.g^-1,and the phosphorus adsorption adsorption amount for 45 days was 3.05 mg.g^-1,2.86 mg.g^-1,2.17 mg.g^-1.The phosphorus-saturated adsorption capacity of the 1% organic fertilizer treatment for 15 days and 45 days was 6.07 mg.g^-1 and 2.96 mg.g^-1,while the negative adsorption of phosphorus was observed after treatment with 2% and 3% organic fertilizer for 15 days.The adsorption thermodynamics of soil phosphorus can be fitted by the Langmuir equation,R² > 0.98.The treatment of various levels of biochar and organic fertiliz er can reduce the adsorption rate of phosphorus by Mollisols,and with the increase of biochar addition,the adsorption rate is not obvious,but with the increase of organic fertilizer,the adsorption rate is significantly reduced.The adsorption kinetics of soil phosphorus can be fitted by the Lagergren quasi-second-order kinetic equation,R²>0.96.?2?Biochar,organic fertilizer and phosphorus-dissolving bacteria can promote the activation of soil phosphorus,and the application of phosphate-dissolving bacteria accelerates the activation rate of soil phosphorus.3% biochar and 3% organic fertilizer can increase soil available P content,soil acid phosphatase activity and organic phosphorus content,and after 30 days,the soil available phosphorus content,acid phosphatase activity and organic phosphorus increased in each treatment.The content of available phosphorus,acid phosphatase and organic phosphorus in biochar and organic fertilizer combined with phosphorus-dissolving bacteria increased compared wit h single-application biochar and organic fertilizer,and after 15 days,the soil acid phosphatase and organic phosphorus content increased with the application of phosphate-dissolving bacteria.?3?Biochar,organic fertilizer treatment and application of phosphate-dissolving bacteria can increase root length,root surface area and root volume compared with CK,biochar treatment can increase plant dry weight and plant height.The treatment of biochar with phosphorus-dissolving bacteria was more important th an biochar treatment,while the dry weight of organic fertilizer treated with phosphate-dissolving bacteria was less than that of organic fertilizer after 20 days of growth.In conclusion,the study showed that the use of biochar and organic fertilizer for improving soil fertility not only supplies phosphorus but also effectively reduces the adsorption of soil phosphorus.This was enhanced by the inclusion of phosphorus-solubilizing bacteria,which seemed to activate the effects on soil phosphorus.