Abstract: The effects of different nitrogen sources on pH and nutrient availability in the rhizosphere of korean pine(Pinus koraiensis) were studied by means of root-mat method.The result showed that the addition of NH~+_4-N decreased the rhizosphere pH value,while the addition of NO~-_3-N increased the rhizosphere pH in contrast with the controled treatment.The direction and extent of the pH change mainly depended on the nitrogen sources and their concentrations applied,and at the same concentration,the extent to which the pH decreased as response to the addition of NH~+_4-N was bigger than that the pH increased as response to the addition of NO~-_3-N.The rhizosphere pH change,as affected by different nitrogen sources,had a remarkable influence on the availability of the micronutrients in the rhizosphere.The addition of NH~+_4-N increased the availability of Fe,Mn,Cu,Zn in the rhizosphere,whereas the addition of NO~-_3-N decreased the availability of Fe,Mn,Cu,Zn in the rhizosphere.However,the addition of both NH~+_4-N and NO~-_3-N had little effects on the availability of Ca and Mg in the rhizosphere.