Appropriate manure application rates, timing, and methods are necessary to maximize nutrient utilization by plants from manure, while minimizing water resource pollution potential, including that of enteric organisms. A field study focused on the movement of fecal bacterial indicators to receiving tile drains through subsurface bacterial leaching. Specifically, the impacts of different manure management regimes on fecal coliform, fecal streptococcus, and Escherichia coli (E. coli) densities in subsurface tile drain water were examined for three years. Six swine manure treatments were compared with a control treatment where commercial urea ammonium nitrate was applied. Manure treatments included standard fall injection, spring injection, and late winter broadcast at application rates of 168 kg N/ha and 336 kg N/ha. Results indicated that the highest incidence of significantly elevated bacterial levels occurred where manure had been broadcast in late winter at a rate of 336 kg N/ha.; In a secondary soil column study, leachate from intact 20-cm diameter, 30-cm long soil columns receiving fall and spring manure applications at 168 kg N/ha and 336 kg N/ha was analyzed for bacterial densities. Fecal coliform, E. coli, and enterococci densities in leachate from the columns were determined for four weekly irrigation events following manure application. While a positive trend between manure application rate and bacterial densities in leachate was observed, this effect was not generally statistically significant at the 10% level. However, an interaction between the application rate and timing was observed, indicating that an increase in application rate is more likely to cause a greater increase in bacterial contamination in subsurface drainage with spring application than with fall application. Manure applied at 336 kg N/ha during the spring often resulted in significantly higher bacterial levels in leachate than other treatments. Bacterial densities in leachate from fall manure-applied soil columns were significantly lower in comparison with bacterial densities in leachate from the spring manure-applied soil columns during the second, third, and fourth irrigation events.
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机译：适当的肥料施用量，时机和方法对于使植物从肥料中吸收养分的效率最大化，同时最大程度地减少包括肠道生物在内的水资源污染潜力，是必需的。一项现场研究的重点是粪便细菌指示剂通过地下细菌浸出转移到接收瓷砖排水口的运动。具体来说，研究了三年内不同粪肥管理制度对粪便大肠菌群，粪便链球菌和大肠杆菌（E. coli）密度的影响。将六种猪粪处理与对照处理进行了比较，在对照处理中应用了商业尿素硝酸铵。粪便处理包括标准的秋季注入，春季注入和冬末播种，施用量分别为168 kg N / ha和336 kg N / ha。结果表明，细菌含量显着升高的最高发生率发生在冬末以336 kg N / ha的速度播撒肥料的地方。在第二项土壤柱研究中，分析了直径为20厘米，长度为30厘米的完整土壤柱中分别以168 kg N / ha和336 kg N / ha施用秋季和春季肥料的渗滤液的细菌密度。在施用粪肥后，每周进行四次灌溉，确定柱中渗滤液中的粪大肠菌群，大肠杆菌和肠球菌密度。虽然观察到渗滤液中肥料施用量和细菌密度之间呈正趋势，但在10％的水平下，这种影响通常没有统计学意义。但是，观察到施药量与施肥时间之间存在相互作用，这表明施药量的增加与春季施药相比，春季施药更可能引起地下排水中细菌污染的增加。春季以336 kg N / ha的施肥量通常会导致沥滤液中细菌水平明显高于其他处理方法。在第二次，第三次和第四次灌溉事件中，与施用春季肥料的土壤柱中的渗滤液相比，来自秋季施用肥料的土壤柱中的细菌密度显着降低。
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