Based on the data of the second national soil survey and the field investigations

the change of soil granularity and soil organic matter in Nenjiang basin during recent twenty years was analyzed by the mathematical statistical method and with the aid of GIS technology. Result showed that soil texture had changed. The percentage of silt was nearly 50% and it had hardly any change during this period. However

the content of sand and clay were different from the survey result. Soil sand particle decreased by 22.95%

while clay particle increased by 50.09%. The soil texture was mainly clay loam and clay

with the area percentage being 32.52% and 66.51%

respectively. In Nenjiang basin

loam decreased by 17.45%

while clay loam and clay increased by 9.34% and 8.20%

respectively. Compared with the second national soil survey

soil organic matter showed a decreasing trend

in the range from 0.55% to 12.26%. The downward trend of soil organic matter in the lower Nenjiang basin was obviously reduced by 33.11%

but in the upper

soil organic matter increased by 27.14%. On the whole

the undeveloped soils in Nenjiang basin do not show serious desertification trend

but soil desertification in the lower region is more serious than in upper region. Soil organic matter has different results in different regions in Nenjiang basin.