Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, K.W. Neatby Building, Ottawa, Ontario K1A 0C6, Canada.
Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, K.W. Neatby Building, Ottawa, Ontario K1A 0C6, Canada.
Sci Total Environ. 2014 Aug 15;490:921-33. doi: 10.1016/j.scitotenv.2014.05.070. Epub 2014 Jun 6.
Estimating the greenhouse gas (GHG) emissions from agricultural systems is important in order to assess the impact of agriculture on climate change. In this study experimental data supplemented with results from a biophysical model (DNDC) were combined with life cycle assessment (LCA) to investigate the impact of management strategies on global warming potential of long-term cropping systems at two locations (Breton and Ellerslie) in Alberta, Canada. The aim was to estimate the difference in global warming potential (GWP) of cropping systems due to N fertilizer reduction and residue removal. Reducing the nitrogen fertilizer rate from 75 to 50 kg N ha(-1) decreased on average the emissions of N2O by 39%, NO by 59% and ammonia volatilisation by 57%. No clear trend for soil CO2 emissions was determined among cropping systems. When evaluated on a per hectare basis, cropping systems with residue removal required 6% more energy and had a little change in GWP. Conversely, when evaluated on the basis of gigajoules of harvestable biomass, residue removal resulted in 28% less energy requirement and 33% lower GWP. Reducing nitrogen fertilizer rate resulted in 18% less GWP on average for both functional units at Breton and 39% less GWP at Ellerslie. Nitrous oxide emissions contributed on average 67% to the overall GWP per ha. This study demonstrated that small changes in N fertilizer have a minimal impact on the productivity of the cropping systems but can still have a substantial environmental impact.
估算农业系统的温室气体（GHG）排放对于评估农业对气候变化的影响非常重要。本研究通过实验数据和生物物理模型（DNDC）的结果相结合，结合生命周期评估（LCA），调查了管理策略对加拿大阿尔伯塔省两个地点（Breton 和 Ellerslie）长期种植系统的全球变暖潜势的影响。目的是估算由于减少氮肥和去除残留物而导致的种植系统的全球变暖潜势（GWP）差异。将氮肥施用量从 75 公斤/公顷减少到 50 公斤/公顷，平均减少了 39%的 N2O 排放、59%的 NO 排放和 57%的氨挥发。在种植系统中，没有确定土壤 CO2 排放的明确趋势。当按每公顷评估时，去除残留物的种植系统需要多消耗 6%的能量，GWP 变化不大。相反，当按可收获生物量的千兆焦耳为基础评估时，去除残留物导致的能量需求减少了 28%，GWP 降低了 33%。在 Breton 和 Ellerslie 两个地点，平均而言，减少氮肥用量对两个功能单位的 GWP 分别减少了 18%和 39%。一氧化二氮排放平均占每公顷总 GWP 的 67%。本研究表明，氮肥的微小变化对种植系统的生产力影响不大，但仍会对环境产生重大影响。
