陕西关中地区冬小麦-夏玉米轮作系统生命周期评价

应用生命周期评价方法分别对陕西关中地区耕作方式存在差异的富平和杨凌两地的冬小麦-夏玉米轮作系统进行评价,分析了轮作系统生命周期对能源消耗、土地资源利用、水资源消耗、全球变暖、环境酸化、富营养化、水体毒性、土壤毒性和人体毒性的影响,得到两地的生态环境综合影响指数分别为0.166 9和0.378 8。富平县小麦、玉米秸秆皆还田,而杨凌区仅小麦秸秆还田,两地的主要环境影响潜在因素不同,分别是富营养化和水体毒性,在冬小麦-夏玉米轮作系统下,富营养化、水体毒性和环境酸化对整个生命周期的生态环境影响较大,富平、杨凌两地的生态环境影响指数分别是0.078 3、0.020 2、0.016 4和0.110 5、0.214 1、0.023 2。农作系统产生了大量引起环境酸化和富营养化的污染物,主要是由于施肥方式不科学和农药施用过量,化肥、农药利用率低,造成了严重的环境负担,因而实施配方施肥、推广低毒农药是降低关中地区冬小麦-夏玉米轮作系统生命周期的生态环境影响的关键。

Life Cycle Assessment of Winter Wheat-Summer Maize Rotation System in Guanzhong Region of Shaanxi Province

Winter wheat-summer maize rotation system is the most common rotation planting system in Guanzhong Region of Shaanxi Province. In this study, the environmental impacts(including energy consumption, land utilization, water utilization, global warming, acidification, eutrophication, water toxicity, soil toxicity, and human toxicity) of this system were evaluated by using life cycle assessment(LCA), on the basis of 1 ton of grain production. The primary data were collected from Fuping County and Yangling District of Guanzhong Region with different tillage practices. Results indicated that the ecological-environmental impact index was 0.166 9 and 0.378 8 for Fuping and Yangling, respectively. The dominating potential impact factors on the environment in two locations were different. In Fuping, eutrophication was the primary factor, whereas water toxicity was the main potential factor in Yangling. In the winter wheat-summer maize rotation system, eutrophication, water toxicity and acidification were the major risks to the ecological environment, and their impact indexes were respectively 0.078 3, 0.020 2 and 0.016 4 in Fuping, and 0.110 5, 0.214 1 and 0.023 2 in Yangling. Irrational fertilization and excessive insecticide spray led to the environmental loads in the winter wheat-summer maize rotation system in the Guanzhong Region.