Abstract: Through adsorption-desorption experiment and incubation test,this paper studied the phosphate adsorption and desorption characteristics of several fly ashes.The test fly ashes contained 0.545～4.540 g·kg^-1 of total P and 19.55～163.0 mg·kg^-1 of available P,which were significantly higher than those in soils.The P adsorption capacity of fly ashes increased with increasing added P,while their P adsorption rate was in adverse.Fly ashes had a higher P adsorption rate but a lower P desorption rate than soils,mainly because fly ashes had more P adsorption sites and stronger bound energy.In this study, Langmuir,Freundlich,and Temkin equations were fit to the measured data, and the MBC value in Langmuir equation,a value in Freundlich equation, and k2 value in Temkin equation could be used as a comprehensive index to characterize the potential phosphate adsorptivity of fly ashes.The larger these values were,the stronger the P adsorptivity was.The MBC,a and k2 value of 5 fly ashes collected from different locations was in order of Xiangtan power factory (5 167.7,4 056.2 and 831.5) ＞Yueyang paper factory (1 650.7,2 803.4 and 711.9)＞Huaneng power factory (303.0,1 677.6 and 368.7)＞Zhuzhou power factory (34.7,413.48 and 213.8)＞Dongting nitrogen fertilizer factory (34.7,413.48 and 213.8).The P fixation by fly ashes generally increased with their increasing water content,and their phosphate adsorption was mainly specific adsorption and chemical precipitation, suggesting that the P fixation and the water content of fly ashes should be considered when fly ash was used as soil amendment or as compound fertilizer filling substance.

Key words: Rhizomatous grasses, Milky ripe stage, Photosynthetic rate, Leaf temperature