Abstract: The performance of diffusive gradient in Thin Film Technique (DGT) for the situ-accumulation of bioavailable elements in natural waters,sediments and soil was investigated in recent years,it could represent the in-situ state of soil solution,the nutrient elements were not changed in the process of sampling and extracting susceptible interferences,and the elements of effective supply of plants could be represented. This study was conducted to evaluate the effects of environment factors on the migration and bioavailability of DGT in soil after phosphate fertilizer was applied. Pot experiments were performed to study the influence of time,temperature and relative soil moisture content on the bioavailable phosphorus. The mobility of phosphate fertilizer in 4 soil types including alluvial soil,anthropogenic-alluvia soil,gray desert soil and meadow soil was determined throughout the surface dressing and drip fertigation using DGT. Results showed that DGT-P was increased with the time (0 hour and 24 hours) and tended to be stable after 24 hours. DGT-P was increased with the increase of relative soil moisture content from 20% to 100%,and the highest DGT-P content was found when the relative soil moisture content varied in a range of 80%-100%. In addition,DGT-P tended to increase with the increase of temperature,and it became stable when the temperature was higher than 25 ℃. Compared with surface dressing,drip fertigation of phosphate fertilizer could be used to increase the DGT-P content in soil layer of 10-15 cm in depth. The migration of DGT-P content was also affected by soil types and texture,the highest migration of phosphorus occurred in meadow soil (71% sand),and the lowest one in alluvial soil (46.65% sand). Our present study indicated that the DGT technique can be successfully used in measuring soil bioavailable phosphorus in 24 hours under the conditions of relative soil moisture content of 80%-100% and temperature of 25 ℃. It was also found that,compared with surface dressing,drip fertigation of phosphate fertilizer could be used to increase the migration of phosphorus.

Key words: diffusive gradients in thin films technique(DGT), bioavailable phosphorus, phosphorus mobility