Concerns about the negative impacts of crop biomass removal on soil ecological functions have led to questioning the long-term sustainability of bioenergy production. To offset this potential negative impact, use of organic C rich by-products from the bioenergy industries have been proposed as a means to replenish soil C in degraded soils. However, the impact of these by-products application on soil carbon dynamics is not fully understood. We measured biogeochemical changes in soil organic C following a three-year field application of two by-products, biochar (BC) and fermentation-by product (FBP), of bioenergy industry processes in an elephant grass [Pennisetum purpureum (L.) Schum.] field. There was a significant increase in overall soil organic C (SOC) observed in BC (270%) treated plots, however the higher labile SOC (51%) content was present in FBP treated plots. Solid-state ¹³C NMR spectroscopy further revealed increased aromatic and alkyl groups in BC amended soils which lend to its significantly higher hydrophobicity index, HI (2.13) compared with FBP amended soils (HI = 0.8). Initial biogeochemical responses of amended soils to drought conditions were also investigated during a short-term experiment with drying and rewetting of soils. Increased concentrations of extractable C and higher stimulation of microbial activities (respiration and enzyme activities) in FBP amended soils were measured. Overall, our results reveal different impacts of the two soil amendments, where FBP soil application can affect the labile SOC availability, and stimulate rapid microbial response in drought affected soils, and biochar soil application lowers the labile SOC and microbial stimulation facilitating C sequestration over time.

对作物生物量去除对土壤生态功能的负面影响的担忧导致人们质疑生物能源生产的长期可持续性。为了抵消这种潜在的负面影响，已提出使用生物能源工业中富含有机碳的副产品作为补充退化土壤中土壤C的手段。但是，这些副产物的应用对土壤碳动力学的影响尚不完全清楚。在三年的现场应用中，我们测量了大象草类生物能源工业过程中两种副产品biochar（BC）和发酵副产品（FBP）的土壤有机碳生物地球化学变化[ Pennisetum purpureum（L.）Schum。]字段。在BC（270％）处理的地块中观察到总体土壤有机碳（SOC）显着增加，但是在FBP处理的地块中存在较高的不稳定SOC（51％）含量。固态¹³13 C NMR光谱进一步揭示了BC改良土壤中芳族和烷基的增加，这使其疏水性指数HI（2.13）明显高于FBP改良土壤（HI = 0.8）。在短期的土壤干燥和再润湿实验中，还研究了改良土壤对干旱条件的初始生物地球化学响应。测量了FBP改良土壤中可萃取C浓度的增加和微生物活性（呼吸和酶活性）的更高刺激。总体而言，我们的结果揭示了两种土壤改良剂的不同影响，其中FBP的土壤施用会影响不稳定的SOC利用率，并在干旱影响的土壤中刺激微生物的快速响应，而生物炭的施用会降低不稳定的SOC和微生物刺激，促进C的固存。