Abstract The first- and second-generation bioethanol by-products (bagasse and fermentation by-product, respectively) have different biochemical characteristics relating to carbon (C) and nitrogen (N) due to their production processes. To examine the impacts of fermentation by-product and bagasse on soil C and N dynamics, a 120 day laboratory incubation experiment was conducted by applying these amendments in soil at an equal carbon application rate (2.2 g C kg−1 soil). There was a significant increase in overall cumulative CO2-C production from amended soil compared to the control soil, though the loss was greatest in bagasse amended soil. However, δ13C-CO2 measurements suggested that fermentation by-product addition suppressed native soil C mineralization and prompted strong negative C priming (−57%). In contrast, bagasse amendment maintained similar native soil C mineralization to control soil. Decreased microbial biomass turnover time appears to be the major driving force for increased CO2-C production and soil C loss following bioethanol by-product amendments. Increased mineral N production indicated net N mineralization after fermentation by-product addition, while addition of bagasse resulted in lower N availability and N immobilization. Overall, results suggested that fermentation by-product application is advantageous in maintaining native soil C stock and N mineralization compared to bagasse. Thus, in a sustainable second-generation bioethanol production system, bagasse may be used for second-generation bioethanol production and the cogenerated by-product could be used as an amendment to improve soil C stock and N availability.

中文翻译：

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比较来自甘蔗的第一代和第二代生物乙醇副产品：对土壤碳和氮动态的影响

摘要 第一代和第二代生物乙醇副产品（分别为甘蔗渣和发酵副产品）由于其生产工艺而具有与碳（C）和氮（N）相关的不同生化特性。为了检查发酵副产物和甘蔗渣对土壤 C 和 N 动态的影响，通过以相同的碳施用率（2.2 g C kg−1 土壤）在土壤中应用这些改良剂，进行了 120 天的实验室孵化实验。与对照土壤相比，改良土壤的总累积 CO2-C 产量显着增加，尽管甘蔗渣改良土壤的损失最大。然而，δ13C-CO2 测量表明，发酵副产物的添加抑制了原生土壤 C 矿化并促使强烈的负 C 引发（-57%）。相比之下，甘蔗渣改良剂保持了类似的原生土壤 C 矿化以控制土壤。在生物乙醇副产品改良后，微生物生物量周转时间减少似乎是增加 CO2-C 产量和土壤 C 损失的主要驱动力。增加的矿物氮产量表明添加发酵副产品后净氮矿化，而添加甘蔗渣导致较低的氮可用性和氮固定。总体而言，结果表明，与甘蔗渣相比，发酵副产品应用有利于维持原生土壤碳储量和氮矿化。因此，在可持续的第二代生物乙醇生产系统中，甘蔗渣可用于第二代生物乙醇生产，而联产副产品可用作改善土壤碳储量和氮可用性的改良剂。