Effects Of Different Combined Phosphate-solubilizing Microbial Fertilizer On Soil Phosphorus Availability And Rapeseed Corn Yield

To improve the utilization rate of phosphate fertilizer, we made combination of phosphate-solubilizing microbial fertilizer using different types of dissolved phosphorus bacteria and fungus fertilizer, and the bacteria and fungus didn't have antagonism reactions which were separated screened from calcareous soil. We set a pot and a field experiment to study the effects of phosphate-solubilizing microbial fertilizer on soil phosphorus availability. The objective of the study was to reduce the application of phosphorus fertilizer. This study mainly got the following results:?1?Rapeseed soil available phosphorus content and alkaline phosphatase activity of different combined phosphate-solubilizing microbial fertilizer were higher than those of CK, and different treatments except inorganic fertilizer were significantly different with CK. Among all treatments, combined phosphate-solubilizing bacteria fertilizer was the most effective. Available phosphorus content and alkaline phosphatase activity with that treatment were significantly higher than that of organic fertilizer treatment, by 15.44%,14.25% respectively. Soil pH contents changed from 8.10 to 8.14 and those did not show significant difference.?2?With increasing exogenous phosphorus concentration, soil phosphorus adsorption rate was decreased, while soil phosphorus adsorption initially increased dramatically, and then gradually changed to be gentle and eventually trend to be balance in different phosphate-solubilizing microbial fertilizer treatments. In each treatment, phosphate-solubilizing bacteria fertilizer's effect on reducing soil phosphorus adsorption capacity was most obvious, followed by phosphate-solubilizing fungus fertilizer.?3?The Langmuir equation was the model that best described phosphorus adsorption isotherm under different treatments. The order of maximum soil phosphorus adsorption capacity and maximum buffering capacity under different treatments was CK>inorganic fertilizer>organic fertilizer>phosphate-solubilizing bacteria mixing fungi fertilizer>phosphate-solubilizing fungus fertilizer>phosphate-solubilizing bacteria fertilizer. Phosphate-solubilizing bacteria fertilizer treatment had the lowest maximum adsorption capacity, adsorption constant and maximum buffering capacity, and it was significantly different with other phosphate-solubilizing microbial fertilizer.?4?Soil phosphorus desorption amount and rate was decreased with increasing exogenous phosphorus concentration. The order of that under different treatments was phosphate-solubilizing bacteria fertilizer>phosphate-solubilizing fungus fertilizer>phosphate-solubilizing bacteria mixing fungi fertilizer> organic fertilizer>inorganic fertilizer>CK. Combined phosphate-solubilizing microbial fertilizer could increase desorption amount and rate, phosphate-solubilizing bacteria fertilizer's effect was most obvious of them. The average desorption rates of combined phosphate-solubilizing bacteria fertilizer, fungus fertilizer and bacteria mixing fungi fertilizer were 9.32%,5.08%,3.39% higher than organic fertilizer.?5?Rapeseed yield and total phosphorus contents under different treatments were significant higher than those of CK. Those of phosphate-solubilizing microbial fertilizer were higher than those of organic fertilizer. Phosphate-solubilizing bacteria fertilizer is the most significant increase of them, which were 27.80%?34.45%?67.18% higher than organic fertilizer, and followed by phosphate-solubilizing fungus fertilizer. Rapeseed chlorophyll contents were different between different treatments, the order of that was phosphate-solubilizing bacteria fertilizer>fungus fertilizer>bacteria mixing fungi fertilizer>organic fertilizer>inorganic fertilizer>CK.?6?Corn soil available phosphorus content and alkaline phosphatase activity with organic or phosphate-solubilizing bacteria fertilizer were higher than those of CK, and bacteria fertilizer's effect was more obvious than organic fertilizer in same fertilizer levels. With the fertilizer levels increasing, they were increased while the growth rate initially increased and then decreased. At different growth periods of corn, soil available phosphorus content were highest in maturating with all treatments. Alkaline phosphatase activity increased with the growth of corn and the difference between treatments was highest in maturating.?7?Corn soil Ca₂-P?Ca₈-P?Al-P and Fe-P content with organic or phosphate-solubilizing bacteria fertilizer were significant higher than those of CK, and those content of bacteria fertilizer were higher than those of organic fertilizer in same fertilizer levels. With the fertilizer levels increasing, they were increased while the growth rate initially increased and then decreased. Phosphate-solubilizing bacteria fertilizer could slightly reduced soil Ca₁₀-P content, and the content decreased with fertilizing amount increasing. Soil O-P content did not show significant difference, and has been less affected by the treatments.?8?Corn yield changed from 505.94 to 748.50 kg/hm² under different treatments, and those of organic or phosphate-solubilizing bacteria fertilizer were significant higher than those of CK. Bacteria fertilizer's effect was more obvious than organic fertilizer in same fertilizer levels. With the fertilizer levels increasing, corn yield increased while the growth rate initially increased and then decreased, that is to say the growth rate changed from fertilizer 150kg/mu to 200kg/mu was significant smaller than that of changed from fertilizer 100kg/mu to 150kg/mu.In conclusion, combined phosphate-solubilizing microbial fertilizer could improve the utilization rate of phosphate fertilizer in soil and increase rapeseed yield, and combined phosphate-solubilizing bacteria fertilizer was the most effective of them. Through field experiment of fertilizer phosphate-solubilizing bacteria fertilizer, we found that organic or bacteria fertilizer could improve the availability of phosphorus and increase corn yield. All of the above indexes were increased with the fertilizer levels increasing, however, the growth range decreased. Therefore, adding fertilizer on the basis of fertilizer 150kg/mu, the effects on improving the availability of phosphorus and increasing corn yield were not significant as well as the economic benefit at a lower level.