西双版纳橡胶园养分变化

通过1977、1987和1998年对西双版纳胶园土壤和橡胶树叶片的三次普查，结果表明：胶园土壤养分含量明显下降，有机质下降幅度为0.25%～1.25%，全氮下降0.023%～0.033%，速效磷下降1.3×10~(-6)～4.2×10~(-6),速效钾下降30×10~(-6)～69×10~(-6)，pH值提高0.1～0.7，土壤酸性下降，有向碱性转化趋势。除个别农场橡胶树叶片某种营养元素略有提高外，大多数农场橡胶树叶片营养元素含量均下降，Mg、K、N三种元素下降明显，Mg降低0.10%～0.20%，K降低0.04%～0.73%，N降低0.20%～0.50%，景洪、东风和勐捧农场1987年橡胶树营养水平比1977年有所提高，是由于其间实施营养诊断施肥的结果。

Change of Nutrients in Rubber Plantation in Xishuangbanna

：The results of investigation and analysis on the siol and leaves show that the content of soil nutrients drop markedly in rubber plantation in Xishuangbanna .The soil organic matter ,total nitrogen,quick-acting phosphors and q-uickacting potassium descend 0.25%～1.25%, 0.023%～0.033%, 1.3×10~(-6)～4.2×10~(-6) and 30×10~(-6)～69×10~(-6)，respecti-vely. The value of pH raises 0.1～0.7.The contents of nutrients in the leaf descend on most farms exception individual farm.The contents of Mg , K and N descend 0.10%～0.20%,0.04%～0.73% and 0.20%～0.50%.The nutrient level was h-igher in 1987 than in 1977 because nutrient guiding fertilization at Jinghong Farm,Dongfeng Farm and Mengpeng Far-m.