广西速生桉施肥对林区内水体富营养物质的影响

Effects of fertilization on eutrophic substance in water body within fast-growing eucalypts plantation

施肥是种植速生桉(Eucalyptus)主要的营林技术措施之一。广西近几年速生桉发展面积较大,施肥量逐年增加,由于肥料通过其气态、淋洗和径流等途径流失到水体,增加了水体中富营养物质的含量。为了防止或减缓速生桉施肥加快对水体富营养化的目的,探索其有效的解决方法,课题组进行了速生桉的施肥数量、肥料颗粒形态、肥料养分含量、肥料养分配比等因子的田间试验,研究不同的施肥处理对林区内水体富营养物质含量的影响。试验结果表明:肥料养分含量越高、施肥量越大、颗粒化程度越低的处理区域水体总氮、总磷和总钾含量越高;桉树林区内水体的总氮、总磷和总钾含量中各有约40%、70%和50%来自桉树施肥,不合理的施肥可能会导致林区内水库或河流等水体富营养化;桉树施肥技术中施肥量对水体营养物质影响最大,其次分别为肥料养分和肥料颗粒形态。建议在一定范围内,速生桉施肥可提高肥料总养分含量、适当减少其施肥量,可防止或减缓桉树林区内水体富营养化。

Fertilization is one of the main silviculture techniques for fast-growing eucalypts. In recent years, large areas of fast-growing eucalypts have been established in Guangxi, accordingly, fertilization amount increases. Due to the reason that the fertilizer is lost into the water body in the form ofgaseity, pouring and runoff, content of eutrophic substance is increased in the water body. In order to prevent or slow down the eutrophication of fast-growing eucalypts fertilization on water body and explore the efficient solutions, the research team has carried out field trial on fast-growing eucalypts＇ fertilization amount, fertilizer grain form, fertilizer nutrient content and proportion, as well as made study on the effects of different fertilizing treatments on eutrophic substance content in water body within plantation. The trial result shows that： the treatment area where the fertilizer nutrient content is higher, fertilizing amount is larger and the fertilizer grain is smaller, then the content of total N, total P and total K is higher. About 40%, 79% and 50% respectively of content of total N, total P and total K in the water body within the eucalypts plantation are from eucalypts fertilization, and inappropriate fertilization will result in the eutrophic substance in reservoir or rivers within plantation area. Among the eucalypts fertilization techniques, the amount of fertilization exerts the greatest impact on water body nutrient substance, followed by fertilization nutrient and fertilization grain form respectively. It is recommended that within a certain area, total nutrient content of fertilization could be increased for fast-growing eucalypts, and fertilization amount could be appropriately decreased in order to prevent or mitigate the eutrophication in water body within the eucalypts plantation.