Effects Of Fertilization On Nutrient Absorption Characteristics And The Law Of C、N、P Ecological Stoichiometry Of Cunninghamia Lanceolata

Nitrogen and phosphorus were important components of the organism, And they were both important limiting factors in soil productivity by affecting the physicochemical characteristics of soil, enzyme activity and microbial reproduction. while carbon through photosynthetic assimilation was a substrate and energy source for plant physiological and biochemical processes. The three nutrients played an important role in plant growth and the various regulating physiological mechanisms and characteristics of stoichiometric ratio can reflect ecological strategy of plant. In this paper, nitrogen and phosphate fertilizers were applied individually or together in four levels to 3-year-old Chinese fir seedlings to study the effects of applied nitrogen and phosphate on soil nutrients concentrations, enzyme activities, stoichiometry characteristics of carbon(C), nitrogen(N) and phosphorus(P) and nutrient limitation in leaves and soil and photosynthetic pigments and plant height of Cunninghamia lanceolata.The main conclusions were as follows:1. Nitrogen fertilizer alone, or nitrogen and phosphorus combined application could significantly improve the contents of soil available nitrogen, the soil available N is increased from45.65mg/kg to 49.98 mg/kg. Phosphorus fertilizer alone or nitrogen and phosphorus combined application could significantly increase the contents of soil available phosphorus(P), the soil available P from 3.54mg/kg to 62.19mg/kg. According to the classification standard of soil nutrients, soil nutrient levels rose. Meanwhile, the nitrogen fertilization could increase the activities of soil invertase, urease, phosphatase and hydrogen peroxidase. Nitrogen mixed with phosphorus fertilization can significantly increase the activities of soil invertase, urease and hydrogen peroxidase but decrease phosphatase slightly, phosphorus fertilization had some differences in soil enzyme activities. The fertilization generally increases the soil nutrients and soil enzyme activities, the fertilization could significantly improve soil fertility and alleviating the decline in soil fertility of Chinese fir seedlings caused by nitrogen and phosphorus deficiencie.2. The application of nitrogen fertilizer, phosphorus fertilizer, and nitrogen mixed with phosphorus fertilizer all increased the contents of C in leaves and soil. The contents of N in leaves and soil were increased with the application of nitrogen fertilizer and nitrogen mixed with phosphorus fertilizer, while they was not significantly affected by the phosphorus fertilizer. Similarly, The P contents in soil and leaves were increased by the application of phosphorus and nitrogen mixed with phosphorus fertilizer, while they was not significantly affected by nitrogen fertilizer. Nitrogen mixed with phosphorus fertilizer was better than single applying nitrogen or phosphorus and the effect of N1P1 treatment was the optimal.3. The responses of soil nutrient contents are sensitive to seasons, the nitrate nitrogen ammonium nitrogen and available P contents showed a decreasing trend overall during the year, The changes of soil enzyme activities are complex, most of the maximum values are often appeared in July.The contents of C and P in leaves increased firstly and then decreased during the during the period of from march to november, but leaves N showed a decreasing trend overall during the period. The contents of C and P in soils decrease firstly and then increase during the year, but soils N showed increase firstly and then decrease. The result indicated that leaf and soil nutrient content changed in keeping with their seasonal growth and development changes and showed some regularity for nutrient demand conditions.4. Applying nitrogen fertilizer significantly reduced the leaf C:N ratio, but the C:P and N: P ratios of leaves increased significantly. Applying phosphorus fertilizer improved leaf C:N ratio by N0P1 and N0P2, except N0P3, and significantly reduced C:P and N:P ratios, and applying nitrogen mixed with phosphorus fertilizer reduced the leaf C:N, C: P and N:P ratios, except N2P1. Single applying nitrogen the growth of Cunninghamia lanceolata seedlings was limited by the P supply. While the phosphorus and nitrogen mixed with phosphorus fertilizer, we could speculated that N1P1 can initially alleviate nutrient limiting conditions, but the others was also limited by N supply. From seasonal dynamics, the leaves C:N and C:P increased firstly and then decreased during the year, but had diffirence with leaves N:P which showed fluctuated change, so that there was no obvious rule.5. The application of nitrogen fertilizer, phosphorus fertilizer, and nitrogen mixed with phosphorus fertilizer all increased the contents of Ct and Car. In general, the plant leaf Chla:Chlb about 3:1, but the test was 2.7:1, Nitrogen and phosphorus fertilizer alone, or their combined application have some differences on plant height, on the whole, their combined application could promote more better, with satisfactory effects with the N1 P treatment.