Abstract: The grey desert soil is the main soil type of Shihezi region, Junggar Basin in northern Xinjiang, China. Samples of the grey desert soil were sampled from NO. 147 farms and Agriculture Experiment Stations of Shihezi University and the physical-chemical characteristics and forms of the inorganic phosphorus were determined. The object was to analyze the availability of Olsen-P in grey desert soil. In the sorption experiments, the influence of the soils physics-chemical properties on the capacity maximizing of P adsorption was analyzed, and the phosphate sorption characteristics of the grey desert soil were also investigated. The results show that the grey desert soils in Junggar Basin were alkaline and had low quantity of soil organic matter. Under the influence of arid climate, the soluble salt and CaCO₃ accumulated in the surface soil. The total phosphorus(TP)contents were the highest in top soil(0-20 cm), followed by those in 20-50 cm and 50-80 cm, which were 926 mg·kg^-1, 734 mg·kg^-1 and 636 mg·kg^-1, respectively. The main typeof inorganic phosphorus(IP)in the grey desert soil was calcium bound phosphorus(Ca-P)which accounted for 75%, following by phosphorus bound to Al(Al-P), phosphorus bound to Fe(Fe-P)and occluded phosphate(O-P). From high to low, the Ca-P fractions ranked as:Ca₁₀-P, Ca₈-P and Ca₂-P. Olsen-P content in all soils were great in variation from 1.18 mg·kg^-1 to 162.14 mg·kg^-1. The number of Olsen-P had significant correlations with the number of Ca₂-P(r=0.990^**), Ca₈-P(r=0.595^**), Al-P(r=0.561^*)and Fe-P(r=454^*). Ca₂-P and Al-P were the most effective phosphate for plants, followed by Ca₈-P and Fe-P, O-P(r=0.045)and Ca₁₀-P(r=0.193)were the potential phosphorus sources. With the increase of soil depth,the percentages of the most effective Ca₂-P, Al-P and Ca₈-P in TP contents decreased and the percentage of Ca₁₀-P increased, leading to Olsen-P the highest in 0-20 soil layerwith the average value of 51.54 mg·kg^-1, and very low in 50-80 cm soil layer with the average value of about 2.62 mg·kg^-1. The maximum P adsorption capacities(Xm) ranged from 328 mg·kg^-1 to 1 586 mg·kg^-1 and the phosphate sorption efficiency(K)ranged from 60.06 to 238.51. Xm had positive correlation(r=0.517, p<0.05)with soil pH values and had significant positive correlation(r=0.728, p<0.01)with the content of clay. Xm had negative correlation(r=-0.472, p<0.05)with the number of soils organic matter and had no obvious correlation with the content of CaCO₃, free ferric oxide, Olsen-P and TP. The influence order on Xm was clay > soil organic matter > pH value. With the increasing of the clay content and pH value, Xm increased. Thus, the grey desert soil with high pH values and clay contents had strong adsorption capacities for P, but the high soil organic matter content didnot benefit for Xm and the content of CaCO₃ had no influence on Xm.

Key words: forms of inorganic phosphorus, sorption characteristics, gray desert soil, Junggar Basin