三倍体毛白杨+黑麦草复合模式根土养分动态研究

Nutrient Dynamics Between Roots and Soils in Triploid populus tomentosa and Lolium multiflorum Lam Plantation

针对退耕还林地三倍体毛白杨幼林与黑麦草牧草复合模式,研究了模式根系养分含量与土壤养分的动态变化.结果表明:模式中植物对土壤速效N的吸收,草根在0.395～0.408 g/kg,变化幅度平稳,树根在0.173～0.369 g/kg,变化幅度较大;对有效P的吸收规律正好与N素相反,树根含量在2.486～3.486 g/kg,变化较平缓,草根在4.572～6.092 g/kg,变化幅度较大;树根K的含量变幅较大,草根在整个年周期中的变幅都较小,而土壤K素供应充分;三倍体毛白杨根系吸收Ca含量是随着林地含量的增加而增加,其变幅在4.651～9.764 g/kg,而草根变幅达8.226～10.877 g/kg,与林地Ca的含量成相反趋势,草根在生活周期中对Ca的吸收影响着交换性Ca的变化;树根和草根生长对Mg的需求分别在10.547～10.744 g/kg和10.365～10.610 g/kg之间,不仅在月动态上相似,且在需求量上也相近,故在平衡施肥中应注意Mg肥的可利用性及生物吸持性.

This paper mainly discussed the monthly dynamic changes of the nutrient content of root and soil＇s nutrient in the model of Triploid populus tomentosa and Lolium multiflorum Lam in cultivating lands to forest.Based on detailed investigating forest lands, analysing samples and processing datum, the conclusions can be drawn：In the model,the number of Lolium multiflorum Lam＇s root absorbing N element was 0. 395- 0. 408 g/kg,and it was higher than that of tree root about 0. 173-0. 369 g/kg,so the tree was the main factor that caused the change of the living being absorbed the N element. But the absorption to efficacious P and N was just in the opposite. The number of tree root＇s absorption was 2. 486-3. 486 g/kg, and that of grass root was 4. 572-6. 092 g/kg. On the other hand,the change of content of tree root＇s K was relatively big, but the grass root＇s change was small,and soil＇s K usually was supplied abundantly. With theCa content in the forest land increasing, the roots＇ of Triploid populus tomentosa increased,and it was 4. 651-9. 764 g/kg,but the grass root＇s absorption was just opposite. The Mg demand of tree root and grass root respectively was 10. 547-10. 744 g/kg and 10. 365-10. 610 g/kg. It was similar not only on the trends of seasonal variation,but also at the number of demand,so the characteristic of utilizing and absorbing should be pay attention to in applying Mg fertilizer.