Wildlife Conservation Research Unit, Department of Zoology, University of Oxford, The Recanati-Kaplan Centre, Tubney House, Abingdon Road, Tubney, Oxon OX13 5QL, UK.
J Environ Manage. 2012 Dec 15;112:309-20. doi: 10.1016/j.jenvman.2012.08.018. Epub 2012 Sep 1.
Organic farming practices have been promoted as, inter alia, reducing the environmental impacts of agriculture. This meta-analysis systematically analyses published studies that compare environmental impacts of organic and conventional farming in Europe. The results show that organic farming practices generally have positive impacts on the environment per unit of area, but not necessarily per product unit. Organic farms tend to have higher soil organic matter content and lower nutrient losses (nitrogen leaching, nitrous oxide emissions and ammonia emissions) per unit of field area. However, ammonia emissions, nitrogen leaching and nitrous oxide emissions per product unit were higher from organic systems. Organic systems had lower energy requirements, but higher land use, eutrophication potential and acidification potential per product unit. The variation within the results across different studies was wide due to differences in the systems compared and research methods used. The only impacts that were found to differ significantly between the systems were soil organic matter content, nitrogen leaching, nitrous oxide emissions per unit of field area, energy use and land use. Most of the studies that compared biodiversity in organic and conventional farming demonstrated lower environmental impacts from organic farming. The key challenges in conventional farming are to improve soil quality (by versatile crop rotations and additions of organic material), recycle nutrients and enhance and protect biodiversity. In organic farming, the main challenges are to improve the nutrient management and increase yields. In order to reduce the environmental impacts of farming in Europe, research efforts and policies should be targeted to developing farming systems that produce high yields with low negative environmental impacts drawing on techniques from both organic and conventional systems.
有机农业实践除其他外，被宣传为减少农业对环境的影响。本荟萃分析系统地分析了已发表的比较欧洲有机和常规农业环境影响的研究。结果表明，有机农业实践通常对单位面积的环境具有积极影响，但不一定对每个产品单位都具有积极影响。有机农场的土壤有机质含量通常较高，单位农田面积的养分流失（氮淋溶、一氧化二氮排放和氨排放）较低。然而，有机系统的单位产品氨排放、氮淋溶和一氧化二氮排放较高。有机系统的能源需求较低，但单位产品的土地利用、富营养化潜力和酸化潜力较高。由于所比较的系统和使用的研究方法不同，不同研究之间的结果差异很大。唯一被发现系统之间存在显著差异的影响因素是土壤有机质含量、氮淋溶、单位农田面积的一氧化二氮排放、能源使用和土地利用。大多数比较有机和常规农业中生物多样性的研究表明，有机农业对环境的影响较低。常规农业的主要挑战是改善土壤质量（通过多样化的作物轮作和有机物质的添加）、回收养分以及增强和保护生物多样性。在有机农业中，主要的挑战是改善养分管理并提高产量。为了减少欧洲农业对环境的影响，应将研究工作和政策集中于开发既能产生高产又能减少负面环境影响的农业系统，这些系统可以借鉴有机和常规系统的技术。
