Wageningen Univ. and Research Centre, Plant Research International, P.O. Box 616, 6700 AP Wageningen, The Netherlands.
J Environ Qual. 2010 Nov-Dec;39(6):2016-28. doi: 10.2134/jeq2010.0035.
Nitrate leaching in intensive grassland- and silage maize-based dairy farming systems on sandy soil is a main environmental concern. Here, statistical relationships are presented between management practices and environmental conditions and nitrate concentration in shallow groundwater (0.8 m depth) at farm, field, and point scales in The Netherlands, based on data collected in a participatory approach over a 7-yr period at one experimental and eight pilot commercial dairy farms on sandy soil. Farm milk production ranged from 10 to 24 Mg ha(-1). Soil and hydrological characteristics were derived from surveys and weather conditions from meteorological stations. Statistical analyses were performed with multiple regression models. Mean nitrate concentration at farm scale decreased from 79 mg L(-1) in 1999 to 63 in 2006, with average nitrate concentration in groundwater decreasing under grassland but increasing under maize land over the monitoring period. The effects of management practices on nitrate concentration varied with spatial scale. At farm scale, nitrogen surplus, grazing intensity, and the relative areas of grassland and maize land significantly contributed to explaining the variance in nitrate concentration in groundwater. Mean nitrate concentration was negatively correlated to the concentration of dissolved organic carbon in the shallow groundwater. At field scale, management practices and soil, hydrological, and climatic conditions significantly contributed to explaining the variance in nitrate concentration in groundwater under grassland and maize land. We conclude that, on these intensive dairy farms, additional measures are needed to comply with the European Union water quality standard in groundwater of 50 mg nitrate L(-1). The most promising measures are omitting fertilization of catch crops and reducing fertilization levels of first-year maize in the rotation.
硝酸盐在集约化草地和青贮玉米型奶牛养殖系统中的淋失是一个主要的环境关注点。本研究基于在荷兰一个实验性和八个试点商业奶牛场的参与式研究方法，在 7 年的时间内收集的数据，在农场、田地和点尺度上，展示了管理实践与环境条件和浅层地下水（0.8 米深度）中硝酸盐浓度之间的统计关系。农场牛奶产量范围为 10 至 24 Mg ha(-1)。土壤和水文特征来自调查，气象站提供天气条件。采用多元回归模型进行统计分析。1999 年农场尺度的平均硝酸盐浓度为 79 mg L(-1)，到 2006 年下降到 63 mg L(-1)，在监测期间，草地下的地下水硝酸盐浓度平均下降，但玉米地的硝酸盐浓度上升。管理实践对硝酸盐浓度的影响随空间尺度而变化。在农场尺度上，氮盈余、放牧强度以及草地和玉米地的相对面积对解释地下水硝酸盐浓度的变异性有显著贡献。平均硝酸盐浓度与浅层地下水中溶解有机碳的浓度呈负相关。在田地尺度上，管理实践以及土壤、水文和气候条件对解释草地和玉米地地下水硝酸盐浓度的变异性有显著贡献。我们得出结论，在这些集约化奶牛场，需要采取额外措施来符合欧盟地下水硝酸盐质量标准 50 mg L(-1)。最有希望的措施是取消覆盖作物施肥和减少轮作中第一年玉米的施肥水平。
