Hooker K V, Coxon C E, Hackett R, Kirwan L E, O'Keeffe E, Richards K G
Dep. of Geology, Trinity College Dublin, Dublin 2, Ireland.
J Environ Qual. 2008 Jan 4;37(1):138-45. doi: 10.2134/jeq2006.0547. Print 2008 Jan-Feb.
Nitrate (NO(3)) loss from arable systems to surface and groundwater has attracted considerable attention in recent years in Ireland. Little information exists under Irish conditions, which are wet and temperate, on the effects of winter cover crops and different tillage techniques on NO(3) leaching. This study investigated the efficacy of such practices in reducing NO(3) leaching from a spring barley (Hordeum vulgare L.) system in the Barrow River valley, southeast Ireland. The study compared the effect of two tillage systems (plow-based tillage and noninversion tillage) and two over-winter alternatives (no vegetative cover and a mustard cover crop) on soil solution NO(3) concentrations at 90 cm depth over two winter drainage seasons (2003/04 and 2004/05). Soil samples were taken and analyzed for inorganic N. During both years of the study, the use of a mustard cover crop significantly reduced NO(3) losses for the plowed and reduced cultivation treatments. Mean soil solution NO(3) concentrations were between 38 and 70% lower when a cover crop was used, and total N load lost over the winter was between 18 and 83% lower. Results from this study highlight the importance of drainage volume and winter temperatures on NO(3) concentrations in soil solution and overall N load lost. It is suggested that cover crops will be of particular value in reducing NO(3) loss in temperate regions with mild winters, where winter N mineralization is important and high winter temperatures favor a long growing season.
近年来，爱尔兰耕地系统中硝酸盐（NO(3)）流失到地表水和地下水中的问题备受关注。在爱尔兰湿润温和的条件下，关于冬季覆盖作物和不同耕作技术对硝酸盐淋失影响的信息很少。本研究调查了这些措施在减少爱尔兰东南部巴罗河谷春大麦（Hordeum vulgare L.）系统中硝酸盐淋失方面的效果。该研究比较了两种耕作系统（基于犁耕的耕作和非翻耕）以及两种越冬方式（无植被覆盖和芥菜覆盖作物）对两个冬季排水季节（2003/04年和2004/05年）90厘米深度土壤溶液中硝酸盐浓度的影响。采集土壤样本并分析无机氮。在研究的两年中，使用芥菜覆盖作物显著减少了翻耕和少耕处理的硝酸盐流失。使用覆盖作物时，土壤溶液中硝酸盐的平均浓度降低了38%至70%，冬季流失的总氮负荷降低了18%至83%。本研究结果突出了排水量和冬季温度对土壤溶液中硝酸盐浓度以及总氮流失量的重要性。研究表明，覆盖作物在冬季温和且冬季氮矿化重要、冬季高温有利于延长生长季节的温带地区减少硝酸盐流失方面具有特别的价值。
