Study On Some Soil Productivity Upgrade Technique Of Triploid Populus Tomentosa Pulp Plantation

The triploid Populus tomentosa is an important species for fast-growing poplar plantation in northern China, and it is very important too to study on the soil procuctivity upgradeof triploid Populus tomentosa pulp plantation. In order to found a optimized and practical soil productivity upgradetechnique and provide theoretical basis and technical reference for the soil productivity maintenance ofplantation, this article studied on the comprehensive benefit of the soil productivity upgrade technology which were:intercropping technique, biological mulching and litter fall management.The methods were field experiments and laboratory analysis.Meanwhile, we also studied the effect of intercropping and alfalfa mulching on the plantation gowth and soil productivity, the dynamic of the natural decomposition of different litter falls and the effect of nitrogen on litter fall decomposition. The main conclusions were as follows:(1) Ml represent the pattern of intercropping alfalfa, M2represent the pattern of intercropping cotton and wheat and M3represent the traditional pattern of Pulp Plantation. Four years later, M1, on average, increased the total increment of DBH, height, individual volume and stand volume by6.04%,2.53%,13.33%and12.07%respectively over M2, while that of M1was28.18%,26.47%,70.00%and10.27%higher than M3. While for understanding the difference of soil fertility among M1, M2and M3, we analyzed the content of soil organic, total N, available N and available K, and found that M1was the best. The total net income of M1reached78043.56yuan/hm and was also the highest. M1increased the net income2982.06yuan/hm2and3.97%over M2, which were21787.56yuan/hm2and38.73%higher than M3too. (2)The alfalfa mulching(T1)had improved the fertility and stand productivity. The content of soil organic, total N, available N, available P, available K in0-40cm soil layer were41.95%-64.01%,35.71%-56.25%,15.56%-50.79%,25.70%-36.43%,27.62%-29.58%higher respectively than TO(CK).(3)The mass loss rate and nutrient release rate of leaf litter were the highest, mixed sample was the second and the branch litter was the least. There were two experimental treatments for external nitrogen experiment:5g/(m2·a)(D2) and10g/(m2·a)(D3). They all promoted the mass loss rate and nutrient release rate of leaf litter, and D3was the best. While the Olson’s single exponent model was adopted to simulate the dynamic of the leaf litter remnant rate, we found that the time of D2and D3when leaf litter was decomposed completely were48days and139days shorten respectively than that of D1.(4)We suggest that M1and T1treatment would be experimental promoted simultaneously in regions similar to our experimental plantation. After intercropping alfalfa for2years, the alfalfa in June should be harvested for mulching to improve the soil fertility and the alfalfa in October should be used as forage grass to develop animal husbandry and increase the income of peasants.