采用盆栽试验对白榆(UImus pumila)单作(BB)、刺槐(Robinia pseudocacia)单作(cc)及白榆/刺槐(U.pumila-R.pseudocacia.)互作(BC)(3种互作方式:根系不分隔(N)、根系用尼龙网(L)分隔和根系用塑料膜(P)分隔)及两种施肥方式(施肥处理(F)和不施肥处理(N))下土壤pH值、土壤养分及植株N、P养分吸收总量的季节变化进行了研究.结果表明,不同处理土壤pH值从5-9月呈增加趋势,互作中根系不分隔处理和根系用尼龙网分隔处理降低土壤的pH值效果较明显;各处理w(土壤有机质)在7月份较高,其中施肥处理＞不施肥处理,在3种互作方式中,w(土壤有机质)大小顺序为:根系不分隔＞根系用尼龙网分隔＞根系用塑料模分隔;随着季节的变化,不同处理土壤销态氮含量呈降低趋势.在白榆、刺槐整个生长期内,w(NH4+-N)占绝大部分,w(N03--N)极少,由此说明在白榆、刺槐整个生长期吸收的氮素形态主要是NH4+-N.不同处理白榆、刺槐植株的N、P养分吸收总量从5月到9月呈现不断增加趋势,至9月达到最大.互作植物N、P养分吸收总量均高于其相应的单作,但不同互作方式对N、P养分吸收总量的变化不同.在3种互作方式中,改善土壤养分状况及植株N、P养分吸收总量的最优互作方式为根系不分隔施肥处理(BCNF).%The seasonal soil pH and nutrients and plant N and P uptakes under the monocultures and mixed plantation of Ulmus pumila and Robinia pseudocacia were studied by three root partition methods ( partitioning their roots by nylon net, no partitioning their roots and partitioning their roots by plastic film ) and two fertilization methods (fertilizing them and not fertilizing them) The results showed that the soil pH increased from May to September in the monoculture and mixed plantation of Ulmus pumila and Robinia pseudocacia . The soil pH decreased significantly in the mixed plantation of Ulmus pumila and Robinia pseudocacia than that of their monocultures, and this particularly appeared more evident where their roots were not partitioned or roots partitioned by nylon net. The soil organic matter contents were higher in July under the monocultures and mixed plantation and higher where fertilization was done than where fertilization was not done, and ranked in the order of not partitioning the roots＞ partitioning the roots by nylon net ＞ partitioning the roots by plastic film. The soil Nitrate-N contents under the monocultures and mixed plantation of Ulmus pumil and Robinia pseudocacia tended to decrease as the seasons changed. In the whole growth periods of Ulmus pumil and Robinia pseudocacia, the soil Ammonium-N made up a great majority of soil N nutrients and the soil Nitrate-N did an exreeme small part of them, which showed that the main form by which Ulmus pumil and Robinia pseudocacia absorbed N was NH4+-N. The total N and P uptakes of Ulmus pumil and Robinia pseudocacia tended to increase from May to September and peaked in September.The total N and P uptakes of Ulmus pumil and Robinia pseudocacia in their mixed plantation were higher than those in their monocultures, but the total N and P uptakes of Ulmus pumil and Robinia pseudocacia under their monoculture and mixed plantation differently varied. The best soil improvement as well as the optimum N and P total uptakes of Ulmus pumila and Robinia pseudoacacia appeared where their roots were not partitioned and they were fertilized.
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