生物炭及炭基硝酸铵肥料对土壤化学性质及作物产量的影响

为了促进生物炭研究和农用,采用盆栽试验研究了两种生物炭基氮肥及相应生物炭对土壤部分化学性质、养分状况及作物产量的影响。试验结果表明：施用生物炭基氮肥可显著提高土壤有机碳含量,提高土壤pH值、阳离子交换量、土壤速效磷、速效钾和矿质态氮含量,增强土壤保肥能力,促进作物增产。生物炭对土壤化学性质和养分状况虽有一定改善作用,但作物增产效应不明显甚至减产。因此,将生物炭与肥料复合制成生物炭基肥料不但可以保持生物炭改良土壤的功能,还可促进作物生长和增产,有利于生物炭农用效益的提升。     

生物炭研究进展及其研究方向

近几年来,随着巴西亚马逊流域考古发现黑土(black earths,或terra preta de indio(葡萄牙语))及研究的深入,认为将生物质炭化还田不仅能藏碳于土,减缓全球气候变化,而且能提高全球粮食安全保障.生物质在无氧或低氧条件下高温裂解炭化而成的产物被称为生物炭(biochar).本文将从生物炭特性;生物炭对作物产量和养分吸收的影响;生物炭分解和对土壤碳周转的影响以及对污染物降解和生物有效性影响方面进行综述,以期为国内生物炭研究提供参考.     

生物质炭对土壤有机质活性的影响

为了解施用生物质炭对土壤碳组分的潜在影响,通过室内2年盆栽培养试验研究施用不同用量生物质炭对土壤有机碳积累、有机碳稳定性、微生物量碳和水溶性有机碳的影响,并与施用等碳量的小麦秸秆、酸洗生物质炭(去除生物质炭中的速效养分)及同时施用小麦秸秆与生物质炭的处理进行比较。结果表明,施用生物质炭可显著提高土壤有机碳的积累,增加土壤有机碳的氧化稳定性,降低土壤水溶性有机碳。施用生物质可在短时间内增加微生物量碳,但随着培养时间的增加,其微生物量碳逐渐下降,最终明显低于对照土壤(不施有机物料的处理)。土壤水溶性有机碳的下降可能与生物质炭对其吸附固定有关,而短时间内激发微生物量碳增加可能与施入生物质炭增加了土壤有效养分、改善土壤微生物生长环境有关。研究结果认为,长期单一施用生物质炭可能会引起土壤有机质生物活性的下降,但生物质炭与一般生物质有机肥配合施用可减免这些负影响。     

几种农林废弃物热裂解制取生物油的研究

农林废弃物是我国农村能源的重要组成部分，对其高品位利用有助于解决农村能源短缺和环境污染问题。该文在流化床反应器上开展了农林废弃物热裂解制取生物油的试验研究，着重对升温速率的影响进行了详细研究，快速升温能有效缩短颗粒在低温阶段的停留时间而抑制炭的生成，有助于提高生物油的产率。比较不同农林废弃物热裂解制取生物油的效果表明：低灰分含量的木屑比稻秆更适合于热裂解制取生物油，而稻秆则适合于气化。同时，农林废弃物热裂解制取生物油技术在生物油的品质经过改性得到提升后，结合炭等副产品的利用，能实现农林废弃物的综合能源化利用。     

利用小型流化床的生物质热裂解影响因素分析

化石能源的储量减少与污染使人们必须寻找其他替代能源,其中生物质能是一个很好的替代品.该文以榆木木屑、红松木屑和秸秆为原料,在自制的小型流化床上开展了生物质热裂解生物油的实验研究.结果表明红松木屑的产油率最高,热裂解的温度对产油率的影响很大,500℃时生物油的产量最高,热裂解温度越高,裂解气体产量越高,气体热值也越高,而碳的产量越低.而且随着反应时间的变化,裂解气体成分也发生变化,在裂解10 min左右,裂解气体中可燃气体成分最高.     

酸性和碱性土壤中芒草生物质炭激发效应的特征与差异

生物质炭是高度芳构化物质,具有极强的物理、化学、生物稳定性,被视为极具潜力的碳封存措施之一。然而,生物质炭施入土壤后,可能会加速土壤有机碳矿化,即产生激发效应。根据δ13C分析原理,向长期种植C3植物、pH为3.70和7.60的两种土壤中,分别加入利用C4植物芒草在350℃(BC350)和700℃(BC700)制成的生物质炭,室内培养180d,定期采样测定CO2和δ13C,以期证实并定量测定生物质炭的激发效应。结果表明,加入生物质炭的土壤,尤其是加入低温生物质炭(BC350)的土壤,有机质矿化明显加快,即产生明显的正激发效应,酸性和碱性土壤的激发效应分别为CO2-C 250和319 mg kg-1。此外,从物理、化学和生物学角度,探究生物质炭激发效应的机理。     

玉米秸秆的催化微波裂解及生物油成分

近年来,生物质热化学裂解已引起了越来越广泛的兴趣。但常规的生物质热裂解技术（如流化床等）要求细小的生物质原材料,因此粉碎能耗大。而且裂解所得的生物油和合成气产物易受生物质粉末污染。微波裂解虽然能帮助解决这些问题,但目前的微波裂解所得的生物油成分和其他热裂解技术一样,仍然过于复杂,因此尽管生物质热解获取生物油的成本低于生物质发酵所获得的燃料,生物质热解技术也仍未在工业上得到推广应用。该研究旨在帮助解决这一难题。利用玉米秸秆颗粒为原料,采用了4%的硫酸或磷酸的预处理,或者采用氯化物等催化剂直接混入原料,然后利用微波进行催化裂解,并获得气态、固态和液态生物油3种产物。利用气质联用设备（GC-MS）,对所得到的液态产物（生物油,Bio-oil）进行成分分析。在大量的试验基础上,该文筛选出的酸预处理,MgCl2、ZnCl2、及AlCl3直接催化是可以使所得的生物油成分简化的实用技术。     

生物质炭对稻田土壤有机碳组分的持效影响

生物质炭的应用已经被认为是以碳封存形式减轻气候变化的有效手段。本研究以一次性施用生物质炭3年后水稻土为对象,分析土壤总有机碳(TOC)、可溶性有机碳(DOC)、颗粒态有机碳(POC)、易氧化态有机碳(ROC)和微生物量碳(MBC)含量的变化,研究施用生物质炭对土壤有机碳和组分的后续影响。结果表明,在10 t hm-2、20 t hm-2和40 t hm-2的生物质炭施用水平下,显著提高土壤有机碳储量,增幅达9.15¹5.49%。施用生物质炭可长期稳定提高土壤TOC、ROC、POC和MBC分别达12.75%15.49%。施用生物质炭可长期稳定提高土壤TOC、ROC、POC和MBC分别达12.75%²3.36%、12.60%23.36%、12.60%²8.00%、10.88%28.00%、10.88%³4.00%和7.97%34.00%和7.97%¹2.35%,且土壤TOC与ROC、MBC极显著正相关,ROC与POC、MBC也存在极显著正相关,这可能与生物质炭可改善土壤结构、促进作物生长有关。因此,施用生物质炭是长期提高水稻土土壤碳储量和活性有机碳含量的有效措施。。     

生物质炭对茶园土壤改良及茶叶品质的影响

近年来,茶树种植过程中化肥的超量施用造成茶园土壤酸化加剧和有机质含量降低等一系列问题,进而影响到茶叶的产量和品质。生物质炭一般呈碱性,具有含碳量高、比表面积大、高度生物化学稳定性和较强的吸附性能等特性,能够增加土壤碳储量,提高土壤pH值和养分有效性,对于茶园土壤固碳、土壤改良和抑制土壤氮磷流失、改善农产品品质等方面有较大作用。针对我国茶园土壤存在的主要问题,以生物质炭的特性及生物质炭改良土壤的作用机理为研究对象,重点阐述了生物质炭在茶园酸化土壤改良、土壤氮素淋失阻控、土壤固碳增汇等方面的效应,以及生物质炭提高茶叶产量和提升茶叶品质方面的作用机理。基于以上研究,展望了生物质炭在茶园管理方面的理论研究方向,为生物质炭在农业生产中的应用和推广提供科学依据。     

中国粮食作物秸秆焚烧排碳量及转化生物炭固碳量的估算

生物质燃烧对全球大气碳排放和气候变化产生重要的影响。近年来,利用生物质制备生物炭实现碳封存备受重视。该文根据2001-2010年中国粮食产量,估算了主要粮食作物秸秆产量,结合秸秆露天焚烧比例及CO和CO2排放因子,得出CO和CO2的排放量及碳排放总量。同时,根据实验室条件下秸秆转化为生物炭的产率及碳含量,估算了中国粮食作物秸秆转化生物炭后固定碳的量。结果发现,中国粮食作物秸秆因焚烧年排放CO、CO2和总碳量分别为1.15×107、1.57×108和4.77×107t。中国粮食作物秸秆全部转化为生物炭后年平均可固碳0.96×108t,如果把每年焚烧秸秆的量全部转化为生物炭可减少近一半因焚烧秸秆排放碳的量,可见,生物炭固碳技术是一种非常有前景的碳汇技术。     

生物质连续热解炭气油联产中试系统开发

针对目前多数生物质炭化设备生产连续性差、能耗高、生产过程中存在焦油水洗二次污染等问题,结合生物质炭化技术最新进展和农林剩余物原料特征,提出了生物质连续热解炭气油联产工艺方案,引入连续分段热解、多级组合除尘脱焦和燃油/燃气回用加热工艺方法.在此基础上,重点突破了多线螺旋抄板物料均匀有序输送、多腔旋流梯级高效换热、保温沉降密封出炭、系统压力与气体组分耦合预警等技术,开发了生物质连续热解中试生产系统.运行检测结果表明:系统运行稳定可靠,温度控制精度为±16℃,反应室压力控制精度为±-25 Pa,以花生壳为原料,原料处理量为28.2 kg/h,生物炭得率为31.3％,热解气产率29.6％,液体产物产率19.8％,热解气低位热值为16.3 MJ/m3,各项技术指标均达到了系统设计目标与要求.该中试系统的开发为设备放大及示范应用奠定了重要基础.     

农林废弃物高效循环利用模式与效益分析

中低慢速热解技术将生物质在绝氧或低氧环境中加热分解,生产生物炭、热解油和不可冷凝气体产物,是农林废弃物高效利用的重要途径。该文基于生物质热解炭气联产技术,构建了农林废弃物能源化资源化高效循环利用应用模式,秸秆炭用于还田,木质炭成型后用于供暖,热解气用于居民炊事和热水,热解油回用燃烧为系统加热,木醋液稀释后用作杀虫剂。前南峪热解联产示范工程年运行5 500～6 000 h的条件下,可处理各类农林废弃物2 500 t,生产生物炭700 t(其中秸秆炭约150 t、木质炭550 t),生产热解气20余万m~3,木质型炭和热解气可满足全村386户居民冬季取暖和全年炊事热水用能需求,秸秆炭与人畜粪便复混,全部用于还田。原料收购采用生物炭兑换方式,本村居民5 t农林废弃物原料兑换1t炭基肥或木质型炭,热解气以0.9元/m~3的价格出售给本村农民,工程运行可持续、可复制,具有良好的社会环境效益。项目可实现农林废弃物的高值利用,改善农村用能结构,促进农业可持续发展。     

Study of Biochar Properties by Scanning Electron Microscope – Energy Dispersive X-Ray Spectroscopy (SEM-EDX)

Biochar is a carbon-rich solid product obtained by pyrolysis of biomass. Here, we investigated multiple biochars produced under slow pyrolysis (235–800 °C), flash carbonization, and hydrothermal carbonization (HTC), using Scanning Electron Microscope—Energy Dispersive X-ray Spectroscopy (SEM-EDX) in order to determine whether SEM-EDX can be used as a proxy to characterize biochars effectively. Morphological analysis showed that feedstock has an integrated structure compared to biochar; more pores were generated, and the size became smaller when the temperature increased. Maximum carbon content (max. C) and average carbon content (avg. C) obtained from SEM-EDX exhibited a positive relationship with pyrolysis temperature, with max. C correlating most closely with dry combustion total carbon content. The SEM-EDX O/C ratios displayed a consistent response with the highest treatment temperature (HTT). The study suggests that SEM-EDX produces highly consistent C, oxygen (O), and C/O ratios that deserve further investigation as an operational tool for characterization of biochar products.     

棉花秸秆炭微波裂解生产设备研制

为了提高棉花秸秆的循环利用效率,分析不同参数对微波裂解棉花秸秆生产秸秆炭的产炭率的影响,该文研制了一套微波裂解设备。微波裂解设备主要由气液处理系统、裂解腔、惰性气体供应系统、恒温控制等组成,工作时微波裂解腔中的磁控管对棉花秸秆的裂解过程提供能量,使棉花秸秆达到炭化的效果。以棉花秸秆的炭产率为指标,以棉花秸秆含水率、炭化时间、微波功率为影响因素,通过Box-Behnken中心组合试验方法对微波裂解设备在裂解棉花秸秆过程中的试验因素进行三因素三水平二次回归试验。分析各因素对产炭率的影响,同时对影响因素进行综合优化。结果表明,棉花秸秆含水率和微波功率对棉花秆秸产炭率影响显著(P<0.01),最优参数组合为含水率11%、炭化时间6min、微波功率1.8 kW。验证试验结果表明,在最优参数条件下,棉花秸秆产炭率为30.9%,与理论值的相对误差为0.71%。研究结果可为棉花秸秆炭微波裂解生产设备的设计和作业参数优化提供参考。     

Wheat growth and yield responses to biochar addition under Mediterranean climate conditions

The effects of the addition of a slow pyrolysis biochar (produced from olive-tree prunings) to a vertisol were studied in a field experiment during one wheat (Triticum durum L.) growing season. The biochar addition did not significantly affect soil parameters such as pH, dissolved organic C and N, ammonium, nitrate or microbial biomass N. By contrast, biochar addition decreased soil compaction and increased the soil water-retention capacity and nutrient content (total N and the available contents of P, K, Mg, Cu and Zn). These favourable changes led to an increase in fine root proliferation (increasing specific root length and reducing root tissue density) and promoted crop development. As a result, the plants in biochar-treated plots showed higher relative growth and net assimilation rates, aboveground biomass and yield than those in control plots. Neither grain quality nor nutrient content were significantly affected by biochar addition. Our results suggest that the use of biochar as a soil amendment in agricultural soils can improve soil physical properties and increase fertility, favouring crop development under semiarid Mediterranean conditions.     

秸秆炭基肥料挤压造粒成型优化及主要性能

炭基肥料是以生物炭为基质与其他肥料复合而成的新型肥料,能有效提高土壤的肥力和透气能力,同时具有对肥料的缓释效果等。为了炭基肥料成型工艺优化及工业化生产,该文以复混肥料的国家标准为参考,尿素、过磷酸钙、磷酸氢二铵、氯化钾作为提供氮磷钾元素的基础肥料,并以秸秆炭为基质,着重讨论了成型前加水量、有无添加胶黏剂和成型前物料粒度对炭基肥料成型的影响。研究成型炭基肥料的较佳工艺为基础肥料质量分数占70.36%,总养分的质量分数为28%,其中N:P2O5:K2O养分质量比为10:8:10,秸秆炭质量分数16.64%,不加研磨,配以13%的水,搅拌均匀常温造粒成型;并对在此条件下成型后的炭基肥料养分含量、含水率、溶水性、强度、pH值和对土壤化学性质的影响等性能进行表征,指标如下:氮质量分数为10.07%,水溶性磷质量分数5.47%,有效磷质量分数8.38%,水溶性磷占有效磷65.27%,钾质量分数10.45%,水分质量分数3.24%,机械强度85%以上,pH值为6.41。实测结果符合国家相应标准,工艺设计简单可行,进而为炭基肥料的工业生产提供参考。     

生物炭在农业土壤中应用的回顾与展望

Soil degradation, characterized by declines in nutrient status and simultaneous accumulation of pesticide residues, is a major problem affecting agricultural ecosystems. Previous studies indicate that biochar application to soil has promise as a practical method to alleviate these pressures: increasing crop yield and enhancing pesticide degradation. Here, we review the roles of biochar in both chemical and biological promotion of pesticide degradation and the potential benefits of biochar relating to the efficiency of fertilizer use, availability of nutrients, and nutrient exchange. Biochar typically has a high surface area featuring many functional groups, a high cation exchange capacity, and high stability. Major factors that impact on the nutrient retention characteristics of biochar (e.g., feedstock, pyrolysis temperature, and application rate) are also discussed herein. Nonetheless, more studies of the long-term impacts on soil properties from biochar addition are still required before it can be possible to accurately quantify the sustainability of this approach to sequester carbon and restore soil function.     

Influence of biochar produced from different pyrolysis temperature on nutrient retention and leaching

Biochar application has been received much attention because biochar can improve the fertilizer utilization efficiency of soil. However, the effect of biochar produced at different temperature on the nutrient retention and leaching remains poorly understood. In this study, we observed the nutrients leaching from a sandy loam soil amended with biochar produced at different temperature. The properties of biochars produced from wheat straw at four contrasting pyrolysis temperatures (250, 350, 450, and 550°C) showed that increasing pyrolysis temperature increased pH value and specific surface area but reduced the electrical conductivity and cation exchange capacity. With the temperature increased, the nitrogen loss was significant decreased (p > 0.05) from 109.6 mg to 53.3 mg in biochar amended soil. However, dissolved organic carbon (DOC), available P, Na and K were significant increased (p > 0.05). These results demonstrate that the pyrolytic temperature has a great influence on biochar properties, which in turn affect the leaching of the available nutrients.     

Manure application followed by biochar application increases plant production regardless of soil dehydrogenase activity

Biochar is obtained by the pyrolysis of biomass, and contains abundant carbon and minerals. Biochar supplementation of soils can greatly improve soil health and quality, but these beneficial effects typically develop slowly over time. Depending on the quality of the biochar and the soil to which it is applied, it may take years before positive effects are apparent. This is because organic substances are slowly sorbed onto the biochar over time, and the biochar eventually becomes part of the sorption complex of the soil. It is therefore advisable to apply biochar together with some organic material. We examined the effect of co-application of different doses of biochar with manure on soil dehydrogenase activity (DHA), soil oxidizable carbon (COX), cumulative soil respiration, soil buffering capacity, the soil exchange reaction (pH/KCl) and the production yield of winter rape seeds. We also determined seed production when artificial granular fertilizers were added to biochar and manure. The results showed that the application of biochar and manure significantly increased grain yield, DHA, the soil exchange reaction and cumulative respiration. Thus, application of biochar with organic material can increase seed yield and some properties of agricultural soils. However, the positive effect of biochar on seed yield was not directly proportional to biochar dose, in that the seed yield was lower for a biochar dose of 45 t/ha than 30 t/ha.     

基于能量得率的棉秆热裂解炭化工艺优化

为了从能源利用角度设计和优化棉花秸秆热裂解制生物炭的热解炭化工艺,该文使用了产率、热值及能量得率3个指标来衡量工艺的优劣。首先,研究了热解温度、保留时间和原料粒径3个工艺条件分别对生物炭产率和热值的影响。结果表明,在3个工艺条件下生物炭产率与热值均呈负相关,即高产率和高热值目标无法同时满足。因此,引入能量得率(单位原料所产生物炭的总能量)作为全面评价生物炭产率和热值的综合指标,重点利用响应面分析法分析了3个工艺条件及其交互作用对能量得率的影响,并经过检验得到优化后的能量得率模型。模型预测结果表明,在炭化温度为429℃,保留时间为1.29 h,原料粒径为0.32 mm时,能量得率达到最大值,为78.95%,通过验证试验证明了模型的有效性。该模型能够用于指导生产高能量得率的生物炭,为生物炭能源高效利用目标的实现提供参考。