Investigation Of Different Phosphorus Fertilizers Transformation And Crop Phosphorus Uptake And Utilization Characteristics In Fluvo-aquic And Yellow-Cinnamon Soils

Phosphorus（P）is one of the essential nutrients for plant growth and development that plays a key role in food production.As a major producer and consumer of P fertilizer,P application plays an important role in ensuring food security in China.However,the fractions transformation and effectiveness of P fertilizer varieties considerably in different soils.At present,there are more studies on the effects of application rates and fertilization methods of single P fertilizer varieties on the yield and P utilization of different crops,but there is a lack of systematic reports on comparative analysis of the transformation of P fractions in different soils by different P fertilizers and the matching of P fertilizers by crops.The study is based on a wheat-rice rotational cropping system with six treatments of no P application（CK）,calcium superphosphate（SSP）,fused calcium-magnesium phosphate（FMP）,diammonium phosphate（DAP）,triple superphosphate（TSP）and ammonium polyphosphate（APP）in the Fluvo-aquic and Yellow-cinnamon soils.To determine the morphological transformation and effectiveness of different P fertilizers in Fluvo-aquic and Yellow-cinnamon soils,and to analyze the rules of P uptake and utilization in wheat and rice,with a view to providing a theoretical basis for the efficient utilization of P by matching P fertilizer—soils—crop systems.The main findings are as follows:（1）P application significantly increased the proportions of H₂O-P and Na HCO₃-Pi in Fluvo-aquic soils during the wheat growing season,and the TSP and DAP treatments had a greater increase in H₂O-P,Na HCO₃-Pi and Na OH-Pi at anthesis of wheat,significantly increasing them compared to no P application by 43.1%,107.4%,43.50%and 38.6%,104.1%and 37.6%,respectively.The magnitude of Olsen-P content in rhizosphere soil of wheat showed a pattern of TSP>DAP>APP>SSP>FMP,with H₂O-P,Na HCO₃-Pi and Na OH-Pi content showed a highly significant positive correlation with the Olsen-P（P<0.05）.The application of SSP and DAP were more effective in enhancing the activity of soil acid and alkaline phosphatase and increased by 37.2%-39.6%and 1.3%-3.1%,0.7%-7.1%and 5.9%-12.7%respectively compared to other P fertilizer treatments.The SSP,DAP and TSP treatments in Yellow-cinnamon soils were the most effective in enhancing the Na HCO₃-Pi and Na OH-Pi contents of the rhizosphere soil at anthesis.No significant difference in the magnitude of rhizosphere soil Olsen-P content between P fertilizer treatments.The Na HCO₃-Pi and Na OH-Pi contents in the rhizosphere soil were significantly（P<0.05）.The TSP and FMP treatments significantly increased rhizosphere soil acid phosphatase activity at anthesis by 10.1%and 13.2%,respectively,and significantly different from the SSP treatment.Soil alkaline phosphatase activity was significantly higher in the FMP treatment by16.8%,21.3%and 16.6%compared to the SSP,DAP and APP treatments,but not significantly different from the TSP treatment.In Fluvo-aquic soils,the application of different varieties of P fertilizers increased shoot P accumulation by 1.3%-42.9%,23.1%-63.0%and 69.0%-94.8%at jointing,anthesis and maturity,respectively,compared with no P application,and there was a significant positive correlation between wheat shoot P accumulation and soil Olsen-P content.Grain yield and P fertilizer use efficiency were significantly higher in the TSP treatment by 19.9%and 73.7%and 28.1%and 94.3%compared to the DAP and FMP treatments,but not significantly different from the APP treatment.The application of different varieties of P fertilizers in Yellow-cinnamon soils significantly increased shoot P accumulation by 102.1%-207.4%and 97.0%-158.7%at the jointing and maturity stages,respectively,compared to no P application.Grain yield was significantly higher in the DAP and TSP treatments by 43.6%and 48.3%,26.7%and 30.9%,and P fertilizer use efficiency by 58.5%and 37.3%,63.5%and 34.9%compared to the SSP and APP treatments.（2）P application in rice seasonal Fluvo-aquic soils significantly increased the proportion of H₂O-P and Na HCO₃-Pi in rice rhizosphere soils at anthesis,with TSP and SSP treatments having the greatest increase in H₂O-P and Na HCO₃-Pi content,with significant increases of 137.4%and 119.3%,204.5%and 176.3%,respectively,compared with no P application.The magnitude of Olsen-P content in the rhizosphere soil at anthesis between P fertilizer treatments showed that TSP>APP>FMP>SSP>DAP,among which H₂O-P,Na HCO₃-Pi,Na OH-Pi and HCl-P content were all significantly and positively correlated with the Olsen-P content（P<0.05）.The DAP,TSP and APP treatments were more effective in enhancing rhizosphere soil alkaline phosphatase activities at anthesis and significantly increased by 40.5%,33.1%and 34.4%,respectively compared to no P application.SSP and DAP treatments in Yellow-cinnamon soils were more effective in enhancing Na HCO₃-Pi and Na OH-Pi content in rhizosphere soils during anthesis.The magnitude of the Olsen-P content of the rhizosphere soil at anthesis between P fertilizer treatments showed FMP>DAP>APP>SSP>TSP,where the content of Na HCO₃-Pi and Na OH-Pi were highly significantly and positively correlated with the Olsen-P content of soil.The direct effect of the two P fractions on Olsen-P reached significant levels（P<0.05）.APP treatment significantly increased soil acidic and alkaline phosphatase activities by 24.2%and 62.2%,43.1%and 34.2%,25.7%and 28.5%compared to SSP,DAP and TSP treatments,respectively.In Fluvo-aquic soils,the application of different varieties of P fertilizers increased shoot P accumulation at anthesis and maturity by 47.1%-84.2%and 44.1%-73.7%,respectively,compared to no P application,and there was a significant positive correlation between rice shoot P accumulation and soil Olsen-P content（P<0.05）.Grain yield and P fertilizer use efficiency were significantly higher in the SSP treatment by23.3%and 44.2%,26.3%and 74.4%compared to the TSP and APP treatments.The application of different varieties of P fertilizers in Yellow-cinnamon soils significantly increased shoot P accumulation at anthesis and maturity by 36.0%-117.5%and 51.4%-91.8%,respectively,compared to no P application,and there was a significant positive correlation between rice shoot P accumulation and soil Olsen-P content.Grain yield and P fertilizer use efficiency were significantly higher in the TSP treatment by 92.5%and 78.7%compared to the DAP treatment,but not significantly different from the APP treatment.In summary,combining the characteristics of the soil available P pool and the efficient use of crop P uptake,the application of triple superphosphate or diammonium phosphate is more effective on Fluvo-aquic and Yellow-cinnamon soils under the wheat cropping system;under the rice cropping system,the application of triple superphosphate and calcium superphosphate is more effective on Fluvo-aquic soils,while the application of ammonium polyphosphate and diammonium phosphate is more effective on Yellow-cinnamon soils.