Study on N, P, and K Uptake and Fertilization of Young‘107'Poplar Clone with Drip Irrigation

Taking ‘107'poplar clone(Populus×euramericana cv.‘74/76')plantation cultivated with surface drip irrigation at sandy land of ancient Yongding River bed in Beijing as the research object, the effects of N, P, and K absorption and accumulation as well as different N fertilization gradient on the growth of 2- and 3-year-old ‘107'poplar clone were studied so as to determine the optimum amount of fertilization for young (2 or 3 year-old) poplar. The results showed that: (1) The nutrient uptake of 1- to 3-year-old ‘107'poplar clone increased year by year, the uptake in the third year was significantly greater than that in the previous two years, and the demand for various nutrients in the order of N > K > P. (2) The growth of 2-year-old ‘107'poplar clone showed no significant difference among various treatments, the minimum N fertilizer (30 g per tree) was the best, the corresponding P was 15 g per tree, K 20 g per tree,which were close to the result of N, P, and K nutrient absorption of 2-year-old ‘107' poplar clone plant (N 28.3 g, P 6.2 g, and K 18.9 g). (3) Among various treatments, the increment of volume of 3-year-old ‘107'poplar clone increased with the increase of N fertilizer. N fertilizer of 80 g per tree achieved the minimum volume increment, and there was significant difference between it and other treatments; 200 g per tree achieved the maximum volume increment, but there was no significant difference among treatments except 80 g per tree of N fertilizer treatment, so 120g N fertilizer per tree was the minimum fertilizer to meet the need for 3-year-old ‘107' poplar clone to grow, the corresponding P was 20 g per tree, K 50 g per tree,which was close to the result of N, P, and K nutrient absorption for 3-year-old ‘107'poplar clone (N 111.8 g, P 16.9 g, and K 43.8 g). 4) Marginal benefit analysis for 3-year-old ‘107'poplar clone plantation showed that N fertilization of 120 g per tree could achieve the maximum marginal income (863.08 yuan·hm-2), so it is the best.