华北高产粮区夏玉米生命周期环境影响评价

以山东省桓台县夏玉米生产体系为例,应用生命周期评价方法,以单位产量为评价功能单元,把夏玉米生命周期分为原料开采与运输、农资生产与运输、作物种植3个生产阶段,对不同施氮水平下夏玉米生命周期的资源消耗与污染物排放进行了清单分析和影响评价.结果表明,随着施氮量的增加,夏玉米生命周期环境影响呈指数上升趋势,其中,主要影响类型为水资源耗竭,这与农作物需水量较大、水分生产率较低有关.在低氮量条件下,主要污染影响类型是全球变暖,随着施氮量的增加,富营养化上升为主要污染影响类型.提高作物种植阶段水肥利用效率是控制夏玉米生命周期环境影响的关键,它可减少夏玉米对水资源和氮肥的需求,从而直接减少农田氮素损失污染影响,也间接降低了上游生产环节的资源消耗与污染物排放影响,进而有助于降低夏玉米生命周期环境影响总潜力.

Life cycle environmental assessment of summer maize in a North China high-yield region

Life cycle assessment was used to establish an inventory of resource use and emissions and to assess life cycle environmental impacts of summer maize production system with different nitrogen fertilizer intensity in Huantai County, Shandong province. The assessment was conducted with per product as the functional unit and the life cycle of the summer maize production system was divided into three phases, including raw material mining & transportation, agricultural production & transportation and crop planting. The results revealed that the life cycle environmental impacts of summer maize production system show an exponential upward trend with the increase of nitrogen fertilizer application. The most significant environmental impact was water depletion because agriculture is a water|intensive industry and water productivity in the study area was low. The most important pollution effect type was global warming at a low nitrogen application rate, but aquatic eutrophication with high nitrogen fertilizer input. As such, to reduce the nitrogen and water consumption as well as to increase their productivities are the key to control the life cycle environmental impacts of summer maize production system, which decrease resource consumption and emissions not only directly in the crop planting stage but also indirectly in the upstream production stage.