利用农田系统中源汇型景观组合控制面源磷污染

通过田间调查、采样分析和小区试验,研究浙江省农田系统中源汇型景观组合及其控制面源磷污染的效果.调查表明,浙江省农田系统中源、汇配置的景观类型主要有:蔬菜地 - 稻田系统、蔬菜地 - 茭白田系统、桑园地 -稻田系统、旱地 - 稻田系统、高施肥稻田 - 低施肥稻田系统、农地(稻田、旱地) - 多塘系统、农地(稻田、旱地) - 植草水道(泥质排水沟)等.不同利用方式农田排水中磷含量有较大的差异,总磷平均含量为桑园>蔬菜地>稻田、小麦田、油菜田>休闲地>茭白田.小区试验表明,利用蔬菜地(旱地) - 稻田 - 茭白系统、蔬菜 - 稻田系统、桑园 - 稻田系统和蔬菜地 - (多)水塘系统可明显降低磷流失.建议对某些养分流失严重的农业流域,通过调整土地利用方式和增加养分汇型景观面积来控制农业面源污染.

Use of the Spatial Matching of Source and Sink Landscapes to Control Non-Point Source P Pollution in Agricultural Watershed

Based on field investigations,chemical analysis of drainage water samples,and field experiments,possibility of controlling non-point source P pollution by matching source and sink landscapes was studied in agricultural watershed.In the agricultural watershed of Zhejiang Province,the major types of source and sink landscapes are vegetable-rice system,vegetable-wild rice system,mulberry-rice system,upland-paddy system,high fertilization rate paddy field-low fertilization rate paddy field system,farmland-multipond system,and farmland-grassy ditch system.P concentration in drainage water from the fields varied with land use,showing a decreasing order of mulberry garden>vegetable land>paddy field,wheat field,rapeseed field>fallow land>wild rice field.Field experiments verified that all the four systems,i.e.vegetable-rice-wild rice system,vegetable-rice system,mulberry-rice system,and vegetable-multipond system,significantly reduced P loss from the systems.Artificial or natural nutrient sink landscapes,such as grassy ditch,grassy filter strip,ponds,and some paddy fields,that are widely distributed in the agricultural system effectively increased P-holding time in the system,and reduced P loss to waters.It is suggested that in agricultural watersheds high in P loss,the runoff of non-point source pollutants could be controlled by adjusting land use structure and increasing the area of nutrient sink landscapes.