Boardman John, Shepheard Mark L, Walker Edward, Foster Ian D L
Environmental Change Institute, Oxford University Centre for the Environment, Oxford, UK.
J Environ Manage. 2009 Jun;90(8):2578-88. doi: 10.1016/j.jenvman.2009.01.018. Epub 2009 Feb 26.
Soil erosion on agricultural land is a growing problem in Western Europe and constitutes a threat to soil quality and to the ability of soils to provide environmental services. The off-site impacts of runoff and eroded soil, principally eutrophication of water bodies, sedimentation of gravel-bedded rivers, loss of reservoir capacity, muddy flooding of roads and communities, are increasingly recognised and costed. The shift of funding in the European Union (EU) from production-related to avoidance of pollution and landscape protection, raises issues of cross-compliance: public support for agriculture has to be seen to give value-for-money. In this context risk-assessment procedures have been introduced to help farmers recognise sites where either certain crops should not be grown or anti-erosion measures are required. In England, Defra [Defra, 2005a. Controlling Soil Erosion: a Manual for the Assessment and Management of Agricultural Land at Risk of Water Erosion in Lowland England. Revised September 2005. Department for Environment, Food and Rural Affairs, London] sets out a system of risk-assessment, including ranking of crops susceptible to erosion and anti-erosion measures, that may be selected. We assess this system using field data for an area of erodible soils in the Rother valley, Sussex. The Defra approach correctly identifies most at-risk fields and, taken together with land-use maps, allows non-compliance with advice to be highlighted. We suggest a simple extension to the system which would further identify at-risk fields in terms of possible damage to roads and rivers from muddy runoff. The increased risk of erosion in the study area is associated with certain crops: potatoes, winter cereals, maize and grazed turnips and seems unlikely to be the result of changes in rainfall which over the last 130 years are minimal. We have not evaluated proposed anti-erosion measures in the area because few have been put into practice. The European Water Framework Directive will increasingly focus attention on agricultural fields as a source of river pollution. Assessing the risk of erosion and the need for field testing of suggested approaches, are not simply issues for the EU, but for the management of global agricultural systems.
西欧农业用地的土壤侵蚀问题日益严重，对土壤质量以及土壤提供环境服务的能力构成威胁。径流和侵蚀土壤的场外影响，主要是水体富营养化、砾石河床河流的泥沙淤积、水库容量损失、道路和社区的泥泞洪水，越来越受到人们的认识和重视，并被计算成本。欧盟的资金从与生产相关转向避免污染和景观保护，引发了交叉合规问题：必须确保对农业的公共支持物有所值。在这种背景下，已引入风险评估程序，以帮助农民识别某些作物不应种植或需要采取防侵蚀措施的地点。在英国，环境、食品和农村事务部（Defra，2005a。控制土壤侵蚀：英格兰低地有水土流失风险的农业用地评估与管理手册。2005年9月修订。环境、食品和农村事务部，伦敦）制定了一套风险评估系统，包括易受侵蚀作物的排名以及可选择的防侵蚀措施。我们使用苏塞克斯郡罗瑟谷一片易侵蚀土壤区域的实地数据对该系统进行评估。Defra方法正确识别了大多数高危田地，结合土地利用图，可以突出显示不符合建议的情况。我们建议对该系统进行简单扩展，以便根据泥泞径流对道路和河流可能造成的损害进一步识别高危田地。研究区域侵蚀风险的增加与某些作物有关：土豆、冬季谷物、玉米和放牧的芜菁，而且似乎不太可能是过去130年降雨量变化极小的结果。我们尚未评估该地区提议的防侵蚀措施，因为很少有措施得到实施。欧洲水框架指令将越来越多地把注意力集中在作为河流污染源的农业田地上。评估侵蚀风险以及对建议方法进行实地测试的必要性，不仅是欧盟的问题，也是全球农业系统管理的问题。
