Abstract:

The purpose of this study was to illustrate the effects of some fertilizers on the soil nutrient content of one-year-old (1 a) and two-year-old (2 a) potted seedlings. The results showed that: on the N-deficient and P-deficient acidic soil, with the increase of N fertilizer on 1 a seedlings, obvious changes in the soil nutrient contents were observed. pH and total potassium content (TK) went down, while the concentration of total nitrogen (TN), hydrolytic nitrogen (HN), water-soluble calcium (Ca) and water-soluble magnesium (Mg) rose up. The variation of total phosphorus (TP), availabe-P(AP), rapidly-available potassium (AK) was unnoted. Some of 1a seedlings were damaged by the overhigh of N concentration. For 2 a seedlings, TN, HN, Ca, and Mg in soil went upward with the increase of N fertilizer, while TK, AK and pH dropped. The change of organic matter and TP was not significant. Differed from 1 a seedlings,the decrease of pH activated the occluded phosphorus and led to the increase of AP, which was good for the growth of the 2 a seedlings. Under the N_deficient and P_deficient conditions, TP, AP, AK and pH went up, while TK, Ca and Mg fell down. But no remarkable change took place for organic matter and HN. The correlation analysis between soil nutrient content and growth indexes indicated that the application of P fertilizer eliminated the P stress and accelerated the growth rate of the 1 a seedlings. For the 2 a seedlings, the gradual increase of P fertilizer made TP, AP ascend and TK descend, but pH, organic matter, TN, AK, Ca and Mg had no notable change. The correlation analysis showed that the use of P fertilizer caused soil nutrition imbalance instead of improving the growth status. The 2 a seedlings were still in the situation of nutrition deficiency. On the N_adequate and P_deficient soil, with the increase of NP compound fertilizer applied to the 2 a seedlings, TN, TP, HN and AP in seedlings climbed up and AK went down. According to the correlation analysis, application of NP compound fertilizer to the 2 a seedlings could enhance the absorption and utilization of AK, resulting the transference of photosynthetic production from leaves to roots, therefore accelerate the growth rate greatly.

Key words: Cunninghamia lanceolata seedling, acid soil, fertilization, nutrient content of soil, correlation analysis