Characteristics Of Phosphorus Contents In The Rhizosphere Of Amorpha Fruticosa

According to the soil phosphorus classification method proposed by Hedley and revised by Tiessen, the available phosphorus, total phosphorus and phosphorus fractions of rhizosphere and bulk soil of different-age Amorpha Fruticosa were analysed in the experiment, The accumulation of soil phosphorus and content characteristics of various form of phosphorus in the rhizosphere micro environment were discussed. The aim of the study is revealling the utilization fact of various rhizosphere nutrients and guiding the use of sand soil nutrients and soil-plant nutrient cycle theory, the preservation and restoration of desert fragile ecosystem is of great value. The experimental results were as follows:1) The maximum contents of Amorpha Fruticosa total phosphorus and available phosphorus occurred both in1951, the total phosphorus content reached to0.96g/kg at0-10cm soil profile in1951, which was the largest phosphorus content among the, different planting years and different soil profile. In all planting years, available phosphorus in the rhizosphere were higher than that in the non-rhizosphere and soil available phosphorus content in the surface soil (0-10cm) were higher than that in the lower layer soil (10-50cm); Enrichment rate of available phosphorus in rhizosphere of Amorpha Fruticosa in1951was18.7%, while phosphorus enrichment in the rhizosphere rate of Amorpha Fruticosa in1983was only0.8%.2) There was significant difference in pH value between the rhizosphere soil and bulk soil in1951,1976and1983planting years, pH in rhizosphere soil decreased by0.4,0.29and0.26, respectively, pH showed no significant difference in rhizosphere soil and bulk soil in2005. The pH value of0-20cm soil reduced with increment of planting years.3) H2O-Pi content is relatively small in the inorganic phosphorus content, Dil.HCl-Pi is the most important inorganic phosphorus morphology, accounting for about50%of the total inorganic phosphorus. In the inorganic phosphorus pool of rhizosphere soil, the highest quantity of inorganic phosphorus was found after60years planting, except H2O-Pi and Conc.HCl-Pi.4) Except NaHCO3-Po in28planting years, the contents of NaHCO3-Pi, NaOH-Pi, NaHCO3-Po, NaOH-Po and Conc.HCl-Po in the rhizosphere were higher than that in bulk soil in different age Amorpha. 5) Available phosphorus in rhizosphere had a significant relationship with Dil.HCl-Pi and Conc.HCl-Po, H2O-Pi and Total-P had a significant relationship, available phosphorus and PH in the rhizosphere and non-rhizosphere did not have a significant relationship with total phosphorus in the rhizosphere.