Abstract:Seedlings of slash pine (Pinus elliottii Engelm.) grown in plastic film bags(15cm×23cm) were treated with liquid fertilizer at 4 relatively different addition rates, i.e.0,53%,64%, and 75%,following the theory and technique of steady state mineral nutrition. The results indicated that the basal diameter, stem length (seedling height), and dry matter production of the seedlings under the 64% treatment increased by 149%,245%, and 396% in comparison with the seedlings under the 0 treatment, which were significantly different at 005 or 001 level. Through quantitative analyses of the available nutrient contents in the root media and the amounts of nutrient element accumulated in the seedlings of various treatments in the beginning and at the end of the experiment, it was shown that 64% treatment was of the best effects with nutrient accumulations of N,P,K elements in seedlings increased by 794%,585% and 419% over the 0 treatment, and the increments of N,P,K,Ca,Mg nutrient element contained in this treatment system by 323%,569%,361%,922% and 253%, respectively in comparison with 0 treatment. At the same time, the soil nutrient flux density of N,P,K increased by 237%,363%,307% in comparison with 0 treatment,respectively, and the enzyme activities of urease,proteinase,hydrogen peroxidase,neutral phosphatase were 403%,455%,40%,1445% higher than those at the beginning of the experiment. It is concluded that the comparatively suitable nutrient relative addition rate not only promotes seedling growth, but also induces soil enzyme activity and soil nutrient flux density, as well as nutrient use efficiency.The mechanism of steady state mineral nutrition to promote soil mineralization, and its advantage were discussed in this paper.