Environmental burdens of producing bread wheat, oilseed rape and potatoes in England and Wales using simulation and system modelling
Environmental burdens of producing bread wheat, oilseed rape and potatoes in England and Wales using simulation and system modelling
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DOI：
10.1007/s11367-010-0212-3
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发表时间：
2010-07
期刊：
影响因子：
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通讯作者：
A. Williams;E. Audsley;D. Sandars
中科院分区：
文献类型：
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作者：
A. Williams;E. Audsley;D. Sandars
背景、目标和范围粮食生产对生活至关重要。现代农业利用大量资源生产可耕种的作物。分析替代作物生产方法的环境负担是决策者的重要工具。本文描述了在英格兰和威尔士使用有机和非有机（当代传统）系统种植的三种主要可耕地作物：面包小麦、油菜和土豆的生产负担（通过生命周期分析计算）。包括资源利用（如非生物和能源）和排放负担（如100年全球变暖潜势、全球变暖潜势、富营养化和酸化潜势）。方法利用系统模型对作物生产进行分析，以便考察氮肥施用量或灌溉等因素的影响。硝酸盐的排放来源于一个模拟模型，在这个模型中，土壤有机氮被驱动到稳定状态，因此所有的长期影响都得到了适当的考虑。对氮的产量响应曲线同样由长期试验得出。作物养分投入和植物保护应用来源于国家调查数据和文献。所有主要投入包括肥料的提取、制造和交付；农药生产;野外燃料使用；机械及建筑制造；作物干燥、冷却和储存。从调查数据中找到了生产系统的当前平衡。加权平均全国产量是根据三种降雨量和土壤质地的组合计算出来的。系统边界是农场大门。功能单位为每件产品1吨适销新鲜重量。结果与讨论面包、小麦、油菜和马铃薯3种主要作物的初级能源需要量分别为2.4、4.9和1.4 GJ/t。当以干物质、蛋白质或能量表示时，小麦的负荷比油菜小，而油菜的负荷比马铃薯低。当然，这些作物都扮演着不同的角色。有机生产的面包小麦所需的能量约为非有机生产的80%，而有机土豆所需的能量比非有机生产的土豆多13%。虽然有机生产中农药的使用始终较低，但其他负担通常不一致地较高或较低。有机生产的土地占用总是较高的。在有机系统中，较低的肥料使用量（以及由此产生的能源使用量）被用于田间工作的更多能量和较低的产量所抵消。主要作物马铃薯的能量需求主要由冷藏控制。降低面包小麦的施氮量可降低能源消耗和全球变暖潜能值。能量的最优值是N为当前水平的70%左右。对于GWP，它似乎要低一些，但所使用的子模型超出了它们的可靠性范围。其结果与其他欧洲研究的结果大致相同。结论在当前的主要生产系统中，农作物生产严重依赖化石燃料。造成全球升温潜能值的排放很大程度上依赖于一氧化二氮，而不是燃料消耗。再加上氨和硝酸盐的排放，意味着农业产生了碳氮足迹，而不是大多数工业生活中典型的碳足迹。鉴于一氧化二氮对全球变暖潜能值的巨大影响，采用另一种方法评估一氧化二氮的排放，例如采用作物-土壤模拟模型代替更为严格的IPCC。
Background, aims and scopeFood production is essential to life. Modern farming uses considerable resources to produce arable crops. Analysing the environmental burdens of alternative crop production methods is a vital tool for policymakers. The paper describes the production burdens (calculated by life cycle analysis) of three key arable crops: bread wheat, oilseed rape and potatoes as grown in England and Wales using organic and non-organic (contemporary conventional) systems. Resource use (e.g. abiotic and energy) and burdens from emissions are included (e.g. global warming potential on a 100-year basis, global warming potential (GWP), and eutrophication and acidification potentials).MethodsCrop production was analysed, using systems models, so that the effects of factors like changing N fertiliser application rates or irrigation could be examined. Emissions of nitrate were derived from a simulation model in which soil organic N was driven to steady state so that all long-term effects were properly accounted for. Yield response curves to N were similarly derived from long-term experiments. Crop nutrient inputs and plant protection applications were derived from national survey data and the literature. All major inputs were accounted for including fertiliser extraction, manufacture and delivery; pesticide manufacture; field fuel use; machinery and building manufacture; crop drying, cooling and storage. The current balance of production systems were found from survey data. The weighted mean national production was calculated from a combination of three rainfall levels and soil textures. The system boundary is the farm gate. The functional unit is 1 t marketable fresh weight of each product.Results and discussionThe primary energy needs for the producing the three main crops were 2.4, 4.9 and 1.4 GJ/t for bread wheat, oilseed rape and potatoes, respectively. When expressed in terms of dry matter, protein or energy, wheat incurred smaller burdens than oilseed rape, which incurred lower burdens than potatoes. The crops do, of course, all play different roles. Organically produced bread wheat needed about 80% of the energy of non-organic, while organic potatoes needed 13% more energy than non-organically produced ones. While pesticide use was always lower in organic production, other burdens were generally inconsistently higher or lower. Land occupation was always higher for organic production. Lower fertiliser use (and hence energy use) in organic systems is offset by more energy for fieldwork and lower yields. Main crop potato energy needs are dominated by cold storage. Reducing the N application rate for bread wheat production reduces energy use and GWP. The optimum for energy is with N at about 70% of the current level. It seems to be lower for GWP, but the sub-models used are beyond their range of reliability. The results are generally of the same order as those from other European studies.ConclusionsArable crop production depends heavily on fossil fuel in current major production systems. The emissions causing GWP are very dependent on nitrous oxide, more so than fuel consumption. That, together with emissions of ammonia and nitrate, means that agriculture has a C-N footprint rather than the C footprint that typifies most industrial life.Recommendations and perspectivesWith the large influence of nitrous oxide on GWP, evaluation of nitrous oxide emissions by another method, e.g. crop-soil simulation modelling instead of the more rigid IPCC …