Organic inputs as a substitution for, or addition to, chemical fertilizers can potentially mitigate N losses. However, it is not well known how their effects on N leaching and runoff depend on application approaches. We conducted a global meta-analysis of 129 studies to compare the effects of organic inputs on N export via leaching and runoff. We compared three application approaches: chemical fertilizer N substituted by organic fertilizer with: 1) equal amounts of total N or, 2) equal amounts of mineral N and 3) additional organic fertilizer N on top of chemical fertilizer. The meta-analysis showed that organic inputs reduced overall N leaching and runoff by 15% and 29%, respectively, without compromising crop yield, and that this effect was significantly influenced by the application approach taken. Organic substitution of chemical fertilizer N with equal amounts of total N decreased both leaching and runoff by more than 30% and hardly affected crop yield. Substitution with equal amounts of mineral N generally increased crop yield by 6% but also increased N leaching by 21%. Organic inputs in addition to chemical fertilizer N did not affect leaching and runoff. The differences between application approaches were reinforced with increased treatment duration. The loss ratios of leaching and runoff were 14% and 4.5%, respectively, from chemical fertilizer, and 9.2% and 2.6%, respectively, from organic fertilizer. The optimal substitution rates differed between leaching (40–60%) and runoff (60–100%) when substitution was based on equal amounts of total N. We conclude that substitution of chemical for organic fertilizer at equal amounts of total N is most effective in reducing N export via leaching and runoff without compromising crop production.

有机投入作为化肥的替代或补充可以潜在地减轻氮的损失。然而，它们对 N 浸出和径流的影响如何取决于应用方法尚不清楚。我们对 129 项研究进行了全球荟萃分析，以比较有机投入对通过浸出和径流输出的氮的影响。我们比较了三种施用方法：用有机肥代替化肥 N：1) 等量的总 N 或，2) 等量的矿物 N 和 3) 在化肥之上添加额外的有机肥 N。荟萃分析表明，有机投入使整体 N 浸出和径流分别减少了 15% 和 29%，而不会影响作物产量，而且这种效果受到所采用的施用方法的显着影响。等量全氮有机替代化肥氮使淋溶和径流均减少30%以上，对作物产量影响不大。用等量的矿物质 N 替代通常使作物产量增加 6%，但也使 N 浸出增加了 21%。除化肥 N 外的有机投入不影响浸出和径流。随着治疗持续时间的增加，应用方法之间的差异得到了加强。化肥浸出和径流损失率分别为14%和4.5%，有机肥分别为9.2%和2.6%。当替代基于等量的总氮时，浸出 (40-60%) 和径流 (60-100%) 的最佳替代率不同。