Finnish N fertilizer application regulations for forage grasses are based on field experiments mainly conducted in the 1960–1970s with cultivars and management practices typical of the time. In order to update the yield response function of N, to make it better suited to current grassland farming, field experiments were conducted at two sites in 2015–2017 with two cultivars of timothy (Phleum pratense L.) and one of meadow fescue (Festuca pratensis Huds.). Dry matter (DM) yield, nutritive value and N balance were evaluated, with N application levels 0, 150, 200, 250, 300, 350, 400 and 450 kg N ha⁻¹ year⁻¹. The grasses were harvested three times per season. The data indicate that the DM yield response was significantly stronger, and N was used more efficiently for DM production than earlier without compromising the nutritive value, especially during the first two years. The third harvest produced on average 23% of the annual yield, utilizing N efficiently. N application rates below 350 kg N ha⁻¹ year⁻¹ did not cause substantial overwintering losses or lodging. The data indicate that with changing climate and improved cultivars and management practices, there is a need to modify the rates and timing of N application. The results suggest that N application levels could be increased by at least 50 kg N ha⁻¹ year⁻¹ from the current maximum accepted rate (250 kg N ha⁻¹ year⁻¹) without too high NO₃^‐ or CP concentrations in feed, or too high N balance that indicates increasing risk of N leaching.

中文翻译：

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施氮量对提摩提和草甸羊茅品种生产力，营养价值和耐寒性的影响

芬兰对牧草的氮肥施用法规基于主要在1960年至1970年代进行的田间试验，该试验采用当时典型的栽培品种和管理方法。为了更新N的产量响应函数，使其更适合当前的草地耕作，2015-2017年在两个地点进行了田间试验，其中两个品种是蒂莫西（Phleum pratense L.）和一个草地羊茅（Festuca）。禾的HUD）。评估了干物质（DM）的产量，营养价值和氮平衡，氮施用量为0、150、200、250、300、350、400和450 kg N ha - ¹年^-1。每个季节收获三遍草。数据表明，DM的产量响应明显更强，并且在不损害营养价值的情况下，尤其是在最初的两年中，氮比早期更有效地用于DM生产。第三次收获平均有效利用了氮，平均年产量达23％。低于350 kg N ha - ¹年^-1的氮肥施用量不会造成大量的越冬损失或倒伏。数据表明，随着气候变化以及品种和管理实践的改善，有必要改变氮肥施用的比例和时间。结果表明，氮肥施用量至少可增加50 kg N ha - ¹年^-1从目前所能接受的最大速率（250千克氮公顷^-1年^-1）不太高NO ₃ ^- ，指示N个浸出增加风险或CP浓度在进料，或过高氮平衡。