Soil Phosphorus Fractionation And Bioavailability Study

Phosphorus (P) is one of the essential nutrients for plant growth, not only the important element in compounds of the plant, but also associated with the various important metabolic activities, and therefore plays a vital role on plant growth.The results showed:1,Basic properties of soil in the various experimental sites were obviously different due to the differences of soil weathering and development in the different latitude regions.2,Soil total phosphorus (TP) and available phosphorus (AP) content were generally decreased from north (Suqian, Jiangsu in this study) to south (Fengcheng, Jiangxi).3,Al-P and Fe-P content in soils were decreased from south (lower latitude) to north (higher latitude) in this study, while Ca-P content was increased, reflecting the effects of soil weathering and development on soil P forms.4,In Hedley fractionation approach, Resin-P and NaHCO3-Pi content had not showed a consistent trend with the latitude changes. NaOH-Pi content in soils was decreased while dilute HCl-Pi in soils was increased with the increase of latitude.5,Basically, NaHCO3-Po and concentrated HCl-Po content in soil was higher in high latitude areas than that in lower latitude areas. The impact of land use on soil NaHCO3-Po content was different by the regions and forest types. However, no any consistent trend with the changes of latitude was observed for Soil NaHCO3-Po.6,A significant positive correlation was observed between TP content and Resin-P content, and between TP and diluted HCl-Pi content respectively. Available phosphorus, Al-P content and Resin-P content, NaOH-Pi showed a significant positive correlation, respectively. Fe-P content and NaOH-Pi also showed a significant positive correlation, but Ca-P content and NaOH-Pi showed a negative correlation. Both Ca-P content in soil and diluted HCl-Pi, and concentrated HCl-Po content showed a positive correlation, respectively.7,In Hedley factions of P, the average total Pi was 65% of total P (Pt) in the various experimental sites, obviously higher than the percent of Po (19%) and residual P (15%). The avarege recovery rate of Hedley method was 90.5%, with a 6.0% of CV, which indicated that the method of Hedley was reasonable in the study of P fractionation.8,The amount of P up taken by poplar seedlings had a significant positive correlation to TP content, Ca-P content, and the diluted HCl-Pi content respectively. And also it had a positive correlation to concentrated HCl-Po content in soil. This probably indicated that those P forms were the resources of available P for poplar growth.