To analyze soil physical and chemical properties in successive Eucalyptus plantation

principal component analysis(PCA)is used by determining principal component factors of soil.Principal component factors in different Eucalyptus generations are compared to illustrate the change of soil fertility .Results show that principal components in 0—20 and 20—40 cm soil layers are basically the same in Eucalyptus plantation .The first principal component composed of soil physical properties and the composition of three soil nutrients(N

P

and K)is the most important factor to soil fertility in the plantation .Integrated soil fertility declines with the increase of crop-rotation generations

especially after the 3rd generation .Integ rated soil fertility is significantly reduced

compared with 1st and 2nd generations .The result indicates that maintaining good soil aeration and water permeability of soil

as well as N

P

and nutrient contents

is very important for maintaining the sustained and healthy development of Eucalyptus plantation .