Characteristics Of Inorganic Phosphorus Pool In Apple Orchard Soil And Effects Of Glucose Addition On Phosphorus Fractions

Phosphorus is one of a large number of elements necessary for apple growth and development.It has a low migration rate in the soil and is easy to be fixed,resulting in low soil phosphorus availability.Soil phosphorus morphology determines the availability of phosphorus.Microorganisms play an important role in the transformation of soil phosphorus morphology,and carbon as an energy substance significantly affects soil microbial activity.Therefore,exploring the interaction of "carbon-soil microorganism-phosphorus form" is of great significance for the efficient use of phosphate fertilizer in low-carbon apple orchards.In this study,through field sampling and pot experiment,the phosphorus status and distribution characteristics of inorganic phosphorus components in different soil layers of apple orchard in different planting years were studied.Effects of glucose on the microbial community composition and phosphorus transformation in soil.Effect of glucose on transformation and availability of different phosphate fertilizer varieties(superphosphate and ammonium polyphosphate).Effects of increasing carbon and reducing phosphorus on apple growth and phosphorus absorption and utilization.the main results are as follows:1.Phosphorus status and inorganic phosphorus composition characteristics of apple orchards in different planting years: The average contents of total phosphorus,inorganic phosphorus,and available phosphorus in 0-40 cm soil layer of apple orchards in Jiaodong area are 0.76 g / kg,681.10 mg / kg,73.05 mg / kg.The planting years significantly affected the soil phosphorus content of apple orchards.With the increase of planting years,the total phosphorus,available phosphorus and inorganic phosphorus contents of the cultivated layer soil showed an upward trend.The total phosphorus,available phosphorus and various inorganic phosphorus components of apple orchard soils with different planting years all showed a decreasing trend as the soil layer deepened.The inorganic phosphorus component mainly exists in the form of Al-P,O-P,followed by Fe-P,Ca-P.The planting years obviously affected the composition of various inorganic phosphorus components.The apple orchard had the highest Al-P ratio in 11-15 years,and the apple orchard had the highest O-P ratio in 16-20 years.Correlation analysis and path analysis results show that Al-P is a relatively effective source of phosphorus in this area.2.Effect of glucose on bacterial community and phosphorus transformation in apple rhizosphere soil: When glucose was applied at 2.5 ~ 7.5 g / kg,total soil phosphorus content decreased by 4.4% ~ 7.3%,and soil acid phosphatase activity increased 0.5 ~ 1.3 times;when the application rate is 10 g / kg,the soil total phosphorus does not decrease significantly,but the acid phosphatase activity is significantly increased by 41.7%;after adding glucose,the rhizosphere soil bacterial community 's diversity and number With a slight increase,the composition of bacterial communities became larger,and the relative abundance of 11 phylums changed significantly,with the most significant change being Proteobacteria.Compared with the control,the addition of glucose significantly increased the relative abundance of phosphate solubilizing bacteria,such as bacillus,Pseudomonas and arthrobacteria,in the rhizosphere soil of apple,and both increased first and then decreased with the increase of glucose addition.When glucose addition was 7.5g/kg,the abundance of phosphate solubilizing bacteria was the highest.3.The effects of glucose on the transformation of different phosphate fertilizer in soil and plant growth and development: without glucose,the biomass,total root length,total root surface area,number of root tips and soil available phosphorus content of ammonium polyphosphate treatment were significantly higher than those of calcium superphosphate treatment.Regardless of whether it is calcium superphosphate or ammonium polyphosphate,compared with no glucose,the addition of glucose significantly increased the relative content of plant biomass,Al-P and medium-active organic phosphorus(ML-OP),and reduced OP and medium stability.Relative organic phosphorus(MS-OP)and high-stability organic phosphorus(HS-OP)relative content.The superphosphate treatment had the highest phosphorus absorption efficiency when the glucose was added at 8 g / kg,and the ammonium polyphosphate had the highest phosphorus absorption efficiency when the glucose application amount was 12 g / kg per kg of soil.4.The effect of increasing glucose and reducing phosphate fertilizer on phosphate utilization and apple growth: Compared with CK without phosphorus,the available phosphorus,total phosphorus,plant biomass,and phosphorus accumulation in the soil treated with phosphorus were significantly higher than The content of CK,Al-P,OP,Ca-P and active organic phosphorus(L-OP)increased significantly,while the content of medium-stable organic phosphorus decreased.Compared with the conventional phosphorus application(P)treatment,the available phosphorus,total phosphorus,plant biomass,and plant phosphorus accumulation in the 70% phosphorus application(0.7P)treatment decreased,and the ratio of OP accumulation in inorganic phosphorus decreased.Conventional phosphorus application(P)was reduced by 8.71%.The effective phosphorus content,plant biomass,and plant phosphorus accumulation in the soil treated with reduced glucose and increased glucose application were significantly higher than those in conventional phosphorus application(P)and 70% phosphorus application(0.7P).Fe-P and medium active organic phosphorus(MLOP)decreased,and active organic phosphorus(L-OP)content increased significantly.The apparent utilization rate of phosphate fertilizer was the highest in 0.7P+C1 treatment(70% of conventional phosphorus application + 2.0 g /kg glucose),and the lowest in 0.7P(70% of conventional phosphorus application)treatment.