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标题：Nitrogen fertilization challenges the climate benefit of cellulosic biofuels
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作者：Leilei Ruan ; Ajay K Bhardwaj ; Stephen K Hamilton 等
期刊名称：Environmental Research Letters
印刷版ISSN：1748-9326
电子版ISSN：1748-9326
出版年度：2016
卷号：11
期号：6
页码：064007
DOI：10.1088/1748-9326/11/6/064007
语种：English
出版社：IOP Publishing Ltd
摘要：Cellulosic biofuels are intended to improve future energy and climate security. Nitrogen (N) fertilizer is commonly recommended to stimulate yields but can increase losses of the greenhouse gas nitrous oxide (N₂O) and other forms of reactive N, including nitrate. We measured soil N₂O emissions and nitrate leaching along a switchgrass (Panicum virgatum) high resolution N-fertilizer gradient for three years post-establishment. Results revealed an exponential increase in annual N₂O emissions that each year became stronger (R ² > 0.9, P < 0.001) and deviated further from the fixed percentage assumed for IPCC Tier 1 emission factors. Concomitantly, switchgrass yields became less responsive each year to N fertilizer. Nitrate leaching (and calculated indirect N₂O emissions) also increased exponentially in response to N inputs, but neither methane (CH₄) uptake nor soil organic carbon changed detectably. Overall, N fertilizer inputs at rates greater than crop need curtailed the climate benefit of ethanol production almost two-fold, from a maximum mitigation capacity of −5.71 ± 0.22 Mg CO₂e ha⁻¹ yr⁻¹ in switchgrass fertilized at 56 kg N ha⁻¹ to only −2.97 ± 0.18 Mg CO₂e ha⁻¹ yr⁻¹ in switchgrass fertilized at 196 kg N ha⁻¹. Minimizing N fertilizer use will be an important strategy for fully realizing the climate benefits of cellulosic biofuel production.