Renewable energy continues to be of interest in the USA due to concerns about the long-termed availability and the environmental impact of fossil fuels. Miscanthus × giganteus is a warm-season perennial bioenergy feedstock grass that has a long growing season, is high yielding, requires limited inputs, and will likely become an important renewable energy crop in the USA. This research studied the effects of N application rates and harvest timings on yields and biomass quality of a 4-year-old stand of M. × giganteus in Urbana, IL, USA. Plots received 0, 56, 112, 156, or 224 kg N ha⁻¹, and harvests were conducted at five dates between August and March in the 2009, 2010, and 2011 growing seasons. Miscanthus × giganteus production increased with N applications up to 112 kg ha⁻¹. Harvesting biomass before senescence, August through November, produced significantly more biomass compared to harvesting biomass after senescence. However, early harvest reduced biomass yields in the following years. Nitrogen fertilization compensated for the yield losses, but the yield gap between early and late harvest continually increased. Harvesting M. × giganteus after senescence optimized long-term productivity, reduced the need for N fertilization, and increased carbon and ash content in the harvested biomass, while harvesting before senescence not only removes N from the plant but also reduces remobilization of other nutrients and carbohydrates in autumn.

由于对化石燃料的长期可用性和环境影响的担忧，可再生能源在美国仍然引起人们的兴趣。芒草（Miscanthus × giganteus）是多年生的暖季生物能源原料草，生长季节长，单产高，需要的投入有限，很可能会成为美国重要的可再生能源作物。这项研究研究了氮肥施用量和收获时间对美国伊利诺伊州厄巴纳（Urbana）4年生雄性按蚊（M. × giganteus）林分的产量和生物量质量的影响。地块收到0、56、112、156或224 kg N ha ^-1，并且在2009年，2010年和2011年生长季节的8月至3月的五个日期进行了收获。施用N量达112 kg ha ^-1时，芒草（Miscanthus × giganteus）产量增加。与衰老后收获生物量相比，8月至11月在衰老之前收获生物量产生的生物量要多得多。然而，早期的收获在随后的几年中降低了生物量的产量。氮肥弥补了产量损失，但收获早期和晚期之间的产量差距不断扩大。收获M. × giganteus 衰老后可以优化长期生产力，减少氮肥的需要，并增加收获的生物量中的碳和灰分含量，而衰老前收获不仅可以从植物中去除氮，还可以减少秋季其他养分和碳水化合物的迁移。