| Eucommia ulmoides Oliv is a kind of specific economic tree in China. Due to every part of the tree can be used, the cultivation of Eucommia ulmoides Oliv has great efficiency in economy, ecology and society. As the development in using of Eucommia ulmoides Oliv, the planting areas of this tree increased significantly in recent years. It could not meet the need of market and production to cultivate this tree in natural way. As a result, the production of the tree is changing from the extensive way into intensified way. Different from the cultivation of other forest, taking off the leaves and bark of Eucommia ulmoides Oliv from the forest makes the nutrients loss, and changes the natural cycle of nutrients in the system. Therefore, to fertilize the Eucommia ulmoides Oliv has become an important problem to be solved in the production.Pot and field experiments carried out at different sites, and field surveying methods were used to analyze the characteristic of nutrient uptake by Eucommia ulmoides Oliv, and evaluate the effects of the fertilizers on the growth of Eucommia ulmoides Oliv. The contents of organic matter, total N, available N, P, and K in 74 soils collected from main cultivating areas of Eucommia ulmoides in the south part of Shaanxi Province were also measured. The following conclusions had been drawn.(1) The single application of N-fertilizer significantly increased the height of tree; and single application of P-fertilizer increased the stem diameter of tree; the application of K-fertilizer had limited effect on tree growth. The application of N combined with P-fertilizer increased the height and stem diameter of tree more significant than their single application; the corresponding value increased for height and stem diameter of tree were 73.5% and 58.5%. And adding N-fertilizer decreased the glue in leaves of the tree; and the combination of N and P fertilizer significantly increased the glue in leaves of the tree by 62.1%.(2) The nutrients uptaked by Eucommia ulmoides mainly existed in its leaves and barks (only 10.7%, 26.7% and 0.5% of N, P, and K existed in the barks); and there was only a limited amounts of nutrients stored in the xylem. Therefore, harvesting the leaves and barks in practice will take out a lot of nutrients from forests. It is essential to add the fertilizers to compensate the nutrients removed. The uptake ratios of N:P2O5:K2O by Eucommia ulmoides was 1:0.3:1.6. Considering the recovery of the fertilizers, it is considered that the ratios of N:P2O5:K2O nutrients added for Eucommia ulmoides is 1:0.6:0.9. In practice, it need to adjust this ratios of N: P2O5:K2O applied according to the nutrients in soil.(3 ) Organic matter, total N, available nutrients in forest soils in the south part of Shaanxiwere commonly deficient; and the level of the soil fertility is low. Compared with available N and K, phosphorus deficiency is more serious. And available P in the soils was a limited nutrient for the growth of Eucommia ulmoides of this region. Therefore, it is necessary to apply the combinations of N, P, and K fertilizers; especially, it needs to pay great attention to the application of P fertilizer.(4) The application of the compound fertilizers specified for Eucommia ulmoides Oliv (ES-Fertilizer) significantly increased the height, and diameter, and biomass of this tree. Compared to the treatment without the fertilizers, the application of ES-Fertilizer in the first year increased the height of Eucommia ulmoides Oliv by 63.0%, and the diameter by 43.2%, and the dry weight of bark by 68.4%, and the weight of leaves by 71.6%, and total biomass weight by 75.8%; and the corresponding increased values to the treatment of application of equal amounts of N, P, and K fertilizer were 20.5%, 17.8%, 25.8%, 56.0%, and 28.6%, respectively. Furthermore, the treatment applied the ES-Fertilizer had a long-term residual of the nutrients.(5) The great growth period of Eucommia ulmoides was in April to July in the south part of Shaanxi; it indicated that the appropriate time to ap... |
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