Abstract: Experimental results of application of labelled 15N and 32P fertilizers to one-year-old younglings of Pinus elliottii and four Aigeiros clones (I-214, I-63/51, I -69/65, and I -72/58) showed that the percentage of recovery of N from the fertilizer in the younglings ranged as low as from 10 to 20% in the year when the nitrogen fertilizer was applied by top-dressing. The proportion of the N uptaken by the younglings from the fertilizer is also a little less than that from soil. The loss of the nitrogen in the fertilizer langed from 60 to 80%, and the N residue left in the soil was less than 20%, sometimes even less than 10% after the first growing season.32P inside the younglings reached its peak value of 30-40 days after application. In general, the time for the 32P activity to reach its peak value tended to postpone and keep longer in younglings which had a longer growing season and a later dormant period. Younglings of different species and even those of different clones of the same species differed considerably in their 32P-absorbing abilities. Clone I-63/ 51 showed the highest 32P-absorbing ability in both pot and field experiments, while clone I-72/58 showed the highest in field experiment. The 32P-absorbing ability of Pinus elliottii seedlings appeared to be strong too. But as compared with weeds (e. g. blue grass) and crops (e. g. soybean) the 32P-absorbing ability of all the kinds of the younglings under test is rather low. Besides, the soil type is also a factor significantly affecting the 32P-absorbing ability of younglings.