Soil organic and inorganic carbon sequestration by consecutive biochar application: Results from a decade field experiment

Biochar addition can expand soil organic carbon (SOC) stock and has potential ability in mitigating climate change. Also, some incubation experiments have shown that biochar can increase soil inorganic carbon (SIC) contents. However, there is no direct evidence for this from the field experiment. In order to make up the sparseness of available data resulting from the long‐term effect of biochar amendment on soil carbon fractions, here we detected the contents and stocks of the bulk SIC and SOC fractions based on a 10‐year field experiment of consecutive biochar application in Shandong Province, China. There are three biochar treatments as no‐biochar (control), and biochar application at 4.5 Mg ha^?1 year^?1 (B4.5) and 9.0 Mg ha^?1 year^?1 (B9.0), respectively. The results showed that biochar application significantly enhanced SIC content (3.2%–24.3%), >53 μm particulate organic carbon content (POC, 38.2%–166.2%) and total soil organic carbon content (15.8%–82.2%), compared with the no‐biochar control. However, <53 μm silt–clay‐associated organic carbon (SCOC) content was significantly decreased (14%–27%) under the B9.0 treatment. Our study provides the direct field evidence that SIC contributed to carbon sequestration after the biochar application, and indicates that the applied biochar was allocated mainly in POC fraction. Further, the decreased SCOC and increased microbial biomass carbon contents observed in field suggest that the biochar application might exert a positive priming effect on native soil organic carbon.     

氮肥减量配施生物炭对稻田有机碳矿化及酶活性影响

氮肥减量配施生物炭对于提升土地生产力、提高土壤碳汇能力以及缓解气候变暖具有重要意义.依托大田试验,设置5个氮肥用量梯度(T0～T4):100％化肥氮,90％化肥氮,80％化肥氮,70％化肥氮,60％化肥氮,采用等氮原则,氮肥减少量用等氮量生物炭替代,以不施肥为对照(CK),结合室内矿化培养,揭示稻田有机碳矿化及酶活性对...     

改性生物炭的吸附作用及其对土壤硝态氮和有效磷淋失的影响

在实验室通过生物炭与FeCl3的不同配比确定了生物炭的最佳改性条件,并利用土柱模拟试验,研究改性生物炭对土壤硝态氮和有效磷淋失的影响。结果表明,Fe3+与生物炭质量比为0.7是最佳改性条件,改性作用大大增强了生物炭吸附硝态氮和有效磷的能力。在含N量为50mg.L-1的KNO3和含P量为50mg.L-1的KH2PO4溶液中,最佳改性炭的吸附量分别比改性前提高了12倍和66倍,氮和磷的理论最大吸附量分别为2.47mg.g-1和16.58mg.g-1。土壤中添加最佳改性炭能够延缓并减少硝态氮和有效磷的淋失,添加量为2.5%、5%和10%与不添加任何物质的对照相比,硝态氮的淋失量分别显著降低20%、43%和59%(P<0.05),有效磷的淋失量分别显著降低45%、59%和75%(P<0.05),表明土壤中添加改性生物炭能够有效降低土壤硝态氮和有效磷的淋失风险。     

施用生物质炭后稻田土壤性质、水稻产量和 痕量温室气体排放的变化

【目的】研究生物质炭对连续两年稻田土壤性质、水稻产量和痕量温室气体排放的影响,为合理施用生物质炭而促进水稻生产可持续的低碳发展提供科学依据。【方法】选择成都平原稻田,2010年布设了施氮与否（0与240 kg N•hm-2）下生物质炭土壤施用（0、20、40 t•hm-2）试验,连续两年观测土壤性质、水稻产量、土壤CH4和N2O排放的变化。【结果】施氮肥条件下,生物质炭连续两年对主要土壤肥力性质表现出改善效应,提高了土壤有机碳、全氮含量和pH,同时降低土壤容重,但对水稻产量影响不显著。生物质炭对CH4排放的影响依氮肥施用而异。不施氮肥下,施用生物质炭提高当季土壤CH4排放（20 t•hm-2用量时）,但次年无影响。施用氮肥下,不同用量生物质炭对土壤CH4排放无显著影响,仅40 t•hm-2用量时次年CH4排放有所增加;生物质炭对不施氮肥土壤当季N2O排放无显著影响,并降低次年的排放。然而,施氮肥下,生物质炭连续两年显著降低了土壤N2O的排放,其降幅高达66%。施氮肥条件下,连续两年生物质炭处理降低稻田痕量温室气体的综合温室效应及其水稻生产的碳强度,特别是40 t•hm-2的高用量下。【结论】在连续两年内,稻田采用生物质炭配施氮肥的管理措施对改善土壤性质和稳定水稻产量具有持续效应,高用量生物质炭(40 t•hm-2)显著降低稻田CH4和N2O痕量温室气体排放的综合温室效应和水稻生产的碳强度,且在连续两年内具有稳定的持续性。因此,在当前稻田管理措施下,生物质炭施用量为40 t•hm-2可实现稻田稳产和固碳减排的目标。     

原料、炭化温度和生物质炭组分对小白菜生长的影响

【目的】探究不同原料、炭化温度和生物质炭不同组分对植物生长的影响,进而揭示生物质炭的增产机制。【方法】分别以木屑和玉米秸秆为原料,在350、450、550℃下裂解得到生物质炭。采用热水浸提法将生物质炭中的可溶性组分（浸提液）与难溶性组分（炭骨架）分离。通过盆栽试验,研究不同生物质炭及组分对小白菜生长的影响。【结果】添加玉米秸秆生物质炭及其各组分处理下,小白菜地上部生物量平均为16.1 g/盆,显著高于添加木屑生物质炭及其各组分（13.0 g/盆）和对照处理（13.5 g/盆）。与地上部生物量类似,添加玉米秸秆生物质炭及其各组分处理下小白菜根长、根表面积、根体积和根尖数等形态学指标较木屑生物质炭和对照处理显著改善。添加炭骨架处理下小白菜地上部生物量平均为16.5 g/盆,较添加原状生物质炭和浸提液分别提高26.9%和17.9%。添加炭骨架处理下小白菜根长、根表面积、根体积和根尖数较添加浸提液处理分别提高64.1%、51.1%、38.3%和80.0%。不同炭化温度裂解得到的生物质炭对小白菜地上部生物量和根系生长无显著影响。与添加原状生物质炭处理相比,添加炭骨架处理下小白菜地上部氮含量提高25.9%,而磷和钾含量分别降低39.7%和14.1%。添加玉米秸秆生物质炭及其各组分处理下土壤pH、有机碳、全氮、速效磷和速效钾含量较添加木屑生物质炭处理分别提高0.1个单位、20.3%、19.1%、29.1%和189.2%。与添加原状生物质炭相比,添加生物质炭骨架处理下土壤有机碳、全氮、速效磷和速效钾含量分别降低14.6%、6.6%、41.3%和55.1%,土壤pH升高0.13个单位;而添加生物质炭浸提液处理下土壤有机碳、全氮和速效磷含量分别降低49.8%、18.9%和24.2%,土壤pH和速效钾含量无显著变化。相关分析表明,不同处理下小白菜地上部生物量与根长、表面积、平均直径、根体积、根尖数等根系形态指标和土壤pH呈正相关,与小白菜地上部磷含量呈负相关。【结论】生物质炭制备原料和组成是影响植物生长的重要因素,玉米秸秆生物质炭较木屑生物质炭有更好的增产效果;玉米秸秆生物质炭经热水浸提后再添加至土壤中有更好的增产效果。生物质炭中可溶性组分对根系生长的促进作用是生物质炭增产的主要机制,而可溶性组分对根系促生作用与原料、制备温度和其本身物质组成密切相关。     

稻草生物炭对甲磺草胺和二氯喹啉酸吸附的影响

以弱酸性除草剂甲磺草胺和二氯喹啉酸为研究对象,研究稻草生物炭对这2种除草剂的吸附特征的影响。结果表明,当在土壤中添加稻草生物炭后,土壤对甲磺草胺、二氯喹啉酸的吸附都显著增加。Friendrich方程能更好地拟合稻草生物炭本身对甲磺草胺的吸附等温线,R2从线性拟合的0.976增加到0.987,Kfads为133.4 mg1-1/nkg-1L1/n。线性方程和Friendrich方程均能很好拟合二氯喹啉酸的吸附等温线,Kd为218.6 L/kg。     

不同温度制备的生物质炭对土壤有机碳矿化及腐殖质组成的影响

在150～600℃范围内制备生物质炭,并通过室内培养实验研究了施加不同温度制备的生物质炭对土壤有机碳矿化及腐殖质组成的影响。结果表明,随热解温度升高,生物质炭比表面积加大,芳香化结构加深。土壤中添加不同温度制备的生物质炭培养400d后,土壤有机碳的含量都有不同程度的增加。土壤有机碳的累积矿化量随热解温度升高而降低,且添加高温(≥400℃)制备生物质炭的土壤CO2累积释放量低于未添加生物质炭的土壤处理;添加低温(<400℃)制备生物质炭增加了土壤腐植酸和胡敏酸含量,而添加高温(≥400℃)制备生物质炭的土壤其腐植酸和胡敏酸含量的变化不显著。另外,添加生物质炭后,土壤H/F皆未发生显著变化,而胡敏酸的E4/E6值则在添加200℃和250℃制备的生物质炭时显著高于其他处理,添加500℃和600℃制备的生物质炭时显著低于其他处理。     

黏土矿物混合生物炭包膜尿素的制备及其氮素污染减排潜力

为促进氮肥高效利用,实现氮素污染减排,选用膨润土和生物炭作为包膜材料,结合硝化抑制剂制备包膜尿素。设置包膜尿素淋溶模拟试验收集淋溶液,结合静态箱法收集N₂O,通过分析NH₄⁺-N,NO₃^--N淋失量和N₂O排放通量对包膜尿素氮素污染减排潜力进行了评估。结果表明:（1）膨润混合土生物炭包膜尿素（F₄）NH₄⁺-N淋溶损失率最低,较纯化肥尿素（F₁）NH₄⁺-N淋溶损失率降低19.76%。（2）硝化抑制剂型膨润土生物炭包膜尿素（F₅）NO₃^--N淋失率最低,较F₁降低16.74%。（3）F₅同时具有最优的N₂O减排效果,N₂O排放量较F₁降低77.8%。F₅氮素减排效果最优,其减排机制在于一方面硝化抑制剂可以从化学过程控制硝化和反硝化进程,延缓尿素酰胺态氮的水解和铵态氮的硝化,在降低NO₃^--N淋失的同时可以实现N₂O减排。另一方面F₅的包膜材料膨润土和生物炭可以通过吸附作用将更多的NH₄⁺-N富集在土壤表层,从而显著降低NH₄⁺-N淋失。综上所述,硝化抑制剂型膨润土生物炭包膜尿素氮素污染减排潜力最优,可使NH₄⁺-N,NO₃^--N和N₂O分别减排15.24%,16.74%和77.8%。     

Challenges in organic component selection and biochar as an opportunity in potting substrates: a review

Plant production in potting substrates provides maximum profit on the applied inputs, and hence, directly improving the socio-economic condition of the grower/nurserymen. The main challenge in this industry is sourcing of materials for their potting substrates. Peat and perlite have been widely preferred materials. However, recently higher prices, more restrictive legislation of many countries and wetland ecosystem destruction through its extraction has limited peat use. Nowadays, producers focus towards peat alternatives that provide good performance, are readily available, inexpensive and environment friendly to attain sustainability in potted plant production. In an effort to grasp sustainability during the last few decades, many industrial and agricultural waste materials were reviewed for their use in potting substrates. In these studies, the major focus remained on material characterization, neglecting their economics, technical aspects and environmental impacts. Thus, switching from peat and perlite to alternatives requires material exploration. In the present review, we summarize a clearer and practical approach for substituting different materials especially biochar to fulfill the need of modern potting substrate industry. Biochar has the potential to sustain the substrate production on a long-term basis.     

Biochar has little effect on soil dissolved organic carbon pool 5 years after biochar application under field condition

Biochar application can improve soil properties, such as increasing soil organic carbon content, soil pH and water content. These properties are important to soil dissolved organic carbon (DOC); however, the effects of biochar on DOC concentration and composition have received little research attention, especially several years after biochar application under field conditions. This study was conducted in a long‐term experimental field where the biochar was only applied once in 2009. The purpose of the study was to investigate the effect of different biochar application rates (0, 30, 60 and 90 t ha^?1) on the dynamics of soil water content, DOC concentration and DOC compositions (reducing sugar, soluble phenol and aromatics) over nine samplings during a 12‐month period in 2014. Our results showed that soil water content and DOC concentration varied from 7.1% to 14.5% and 59 to 230 mg C kg^?1 soil during the 12 months, respectively. However, the biochar application rates did not significantly (p > 0.05) affect soil water content, DOC concentration and DOC composition at the same sampling period. The DOC concentration across the biochar treatments was positively correlated to soil water content. Moreover, the DOC composition (reducing sugar, soluble phenol or aromatics) and their concentrations were positively correlated to the total DOC concentration. In addition, biochar did not affect soil bulk density, pH, saturated hydraulic conductivity and crop yields. The results indicated that some benefits of biochar to soil may not persist 5 years after the application of biochar under a field condition.