Soil and Water Sciences Department, University of Florida, Gainesville, FL 32611, USA.
Soil and Water Sciences Department, University of Florida, Gainesville, FL 32611, USA.
Sci Total Environ. 2019 Feb 25;653:1354-1363. doi: 10.1016/j.scitotenv.2018.10.237. Epub 2018 Oct 18.
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 C 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.
人们对作物生物量去除对土壤生态功能的负面影响感到担忧，这引发了对生物能源生产的长期可持续性的质疑。为了抵消这种潜在的负面影响，有人提议利用生物能源产业的富含有机碳的副产品来补充退化土壤中的土壤碳。然而，这些副产品应用对土壤碳动态的影响尚未完全了解。我们在象草（Pennisetum purpureum（L.）Schum.）田间进行了为期三年的生物炭（BC）和发酵副产品（FBP）田间应用，测量了土壤有机碳的生物地球化学变化。在 BC（270%）处理的地块中，观察到土壤有机碳（SOC）总量显著增加，但在 FBP 处理的地块中，更高的易分解 SOC（51%）含量存在。固态 C NMR 光谱进一步揭示了 BC 改性土壤中增加的芳族和烷基基团，这使其具有显著更高的疏水性指数 HI（2.13），而 FBP 改性土壤的 HI 值为 0.8。在土壤短期干湿循环实验中，还研究了改性土壤对干旱条件的初始生物地球化学响应。在 FBP 处理的土壤中，可提取碳的浓度增加，微生物活性（呼吸和酶活性）的刺激作用增强。总的来说，我们的结果揭示了两种土壤改良剂的不同影响，其中 FBP 土壤应用会影响易分解 SOC 的可用性，并刺激干旱土壤中快速的微生物响应，而生物炭土壤应用会降低易分解 SOC 和微生物刺激作用，从而促进长期的碳固存。
