Abstract: S. babylonica and S. matsudana are not only fine ornamental trees in cities butalso important afforestation tree species of shelter forest and stand for timber.These two species have yellows of different extent in Chernozem of Harbinand Daqing. Leaves, at least. become yellow, white, thin, and small when openingup. At most serious condition, leaves drop off early;the top of a tree becomeswithered;whole tree becomes dead finally, Generally total leaves of most of theseedlings become yellow. The yellows influences normal growth of big seedlingsand seedling quality. so causes certain losses in nursery. Production departementputs forward pressing demand to solve the Problem.We studied the yellowing of S. babylonica and S. matsudana according toproductive need from 1989 to 1992. Through study we ruled out the cause ofinfected disease firstly and firmly believed that it was because of bad ecologicalcondition.Then through further research we found that the cause was soilobstruct.Through the measurement of the pattern of soil profile foue andCaCO₃ content, Hcf reaction, PH, ofganic matter, effective Fe and Mn of soil ofdifferent layers, and through the measurement of chlorophyll content, total Fe-content of the yellowing and normal leaves and through the dressing of be to theyellowing seedings, we concluded finally that soil is short of effective Fe becauseo f a great quantity of CaCO₃ and high soil PH, which affects Fe absorption ofroot system, Fe movement in tree and its effectiveness. Soil Fe can not meet theneed of normal growth of S. babylonica and S. matsudana, So they express chlorosis.This study puts fortvard several suggests to provent chlorosis of S. babylonica and S. matsudana. This chill have important guidillg significance for production.

Key words: S. matsudana, S. babylonica, The yellows, Soil conditions