Abstract The deterioration of water quality in Ireland over the past thirty years and the nutrient losses from agriculture are of particular concern to policy makers. Agri-environmental schemes (AES) are designed to improve the environment and water quality. One of the more common AES measures is the exclusion of cattle from watercourses. Cattle exclusion provides a number of benefits such as reduction in nitrogen, phosphorus and sediment run-off, riverbank stability and improved vegetation cover and biodiversity. Using GIS methods a new national farm boundary spatial database SLIDE (Spatial Land Identification Database for Eire) is created utilising national administrative data and a spatial data storage model. This is the first examination of cattle exclusion and its cost effectiveness at the individual farm level across a national population of farms. Benefits are measured in the form of reduced in-stream faecal deposits. The spatial distribution of cost-effectiveness at the sub-catchment level highlights the differences between areas in terms of costs, benefits and extent. A cluster analysis is used to aggregate results. This information is utilised to undertake an ex-ante examination of the implications of a national policy to restrict cattle access to waterbodies for specific categories of farmers, under the EU Nitrates Directive. The analysis of the clusters show that due to the reduction of faecal deposition in watercourses, fencing on medium and high intensity farms is ∼20 % more cost effective relative to farms with lower livestock densities. This study makes an important contribution to the literature in broadening our understanding of the impacts of policy decision making at the individual farm level and also the costs and scale of AES measures at a national level.

中文翻译：

---

将牲畜排除在水道之外：政策有效性和影响

摘要 过去 30 年爱尔兰水质的恶化和农业造成的养分流失是决策者特别关注的问题。农业环境计划 (AES) 旨在改善环境和水质。更常见的 AES 措施之一是将牛排除在水道之外。牛群排除提供了许多好处，例如减少氮、磷和沉积物径流，河岸稳定以及改善植被覆盖和生物多样性。使用 GIS 方法，利用国家行政数据和空间数据存储模型创建了一个新的国家农场边界空间数据库 SLIDE（爱尔兰空间土地识别数据库）。这是第一次在全国农场人口的个别农场层面对牛排除及其成本效益进行检查。效益以减少的河道内粪便沉积物的形式衡量。子流域水平成本效益的空间分布突出了区域之间在成本、收益和范围方面的差异。聚类分析用于汇总结果。该信息用于根据欧盟硝酸盐指令对限制特定类别农民的牛进入水体的国家政策的影响进行事前检查。集群分析表明，由于减少了水道中的粪便沉积，中高强度农场的围栏相对于牲畜密度较低的农场来说成本效益高约 20%。