Carbon potentials of different biochars derived from municipal solid waste in a saline soil

There are numerous studies conducted on biochar for its carbon (C) sequestration potential;however,there are limited studies available on the behavior of salt-affected soils related to biochar application.Therefore,more studies are needed to elucidate the mechanisms through which biochar affects saline soil properties.In this study,biochars were produced from solid waste at pyrolysis temperatures of 300,500,and 700?C (BC300,BC500,and BC700,respectively)and applied to a saline soil to evaluate their impacts on soil carbon dioxide (CO₂) efflux,C sequestration,and soil quality.A soil incubation experiment lasting for 107 d was conducted.The results showed that soil CO₂ efflux rate,cumulative CO₂ emission,active organic C (AOC),and organic matter (OM)significantly increased with BC300 application to a greater extent than those with BC500 and BC700 as compared to those in the no-biochar control (CK).However,soil C non-lability did not significantly increase in the treatments with biochars,except BC700,as compared to that in CK.Besides improving the soil quality by increasing the soil AOC and OM,BC300 showed positive impacts in terms of increasing CO₂ emission from the saline soil,while BC500 and BC700 showed greater potentials of sequestering C in the saline soil by increasing the soil non-labile C fraction.The recalcitrance index (R50) values of BC500 and BC700 were>0.8,indicating their high stability in the saline soil.It could be concluded that biochars pyrolyzed at high temperatures (?500?C)could be suitable in terms of C sequestration,while biochars pyrolyzed at low temperatures (?300?C) could be suitable for improving saline soil quality.     

Effect of Organic Residues and Their Derived Biochars on the Zinc and Copper Chemical Fractions and Some Chemical Properties of a Calcareous Soil

ABSTRACT

Addition of more resistant organic materials, such as biochars, to soils not only enhances soil C sequestration but also can also benefit soil fertility. The aim of this study was to investigate the effect of two organic materials (sheep manure and vermicompost) and their biochars produced at two pyrolysis temperatures (300 and 500°C) applied at 5% (w/w) on the chemical fractions of Zn and Cu and some chemical characteristics of an unpolluted, light textured calcareous soil. Addition of the raw organic materials and their-derived biochars significantly enhanced plant available K, P, and Zn but significantly decreased plant available Cu in the soil. Sheep manure biochar produced at 300°C was most effective at increasing plant available P (13-fold) and K (1.9 fold) likely due to formation of more soluble forms of P and K compared to raw material or biochar produced at higher temperature (500°C). Whereas, raw vermicompost and sheep manure were most effective at enhancing plant available Zn, by increasing water soluble and exchangeable Zn fraction likely due to organic complexation. All amendments, especially biochars produced at 300°C reduced water soluble and exchangeable Cu mainly attributed to increased soil P availability. The results of this study showed that in the short-term, addition of the low-temperature biochars was best for enhancing soil P and K availability, but concomitantly reduced Cu availability the most, whereas, addition of the raw organic materials was better for enhancing Zn availability compared to the biochars.     

Chemical fractions and bioavailability of nickel in a Ni-treated calcareous soil amended with plant residue biochars

ABSTRACT

Recently, the use of biochars for stabilization of soil heavy metals has been expanded due to their adsorption characteristics, low cost and carbon storage potential. A factorial experiment was performed to investigate the effects of two plant residue biochars (licorice root pulp and rice husk biochar each applied at 2.5% (w/w)) produced at two temperatures (350 and 550 °C), and three Ni application rates (0, 150 and 300 mg Ni kg^?1) on bioavailability and chemical fractions of Ni in a calcareous soil after spinach cultivation. Application of all the biochars significantly reduced Ni bioavailability factor (5–15%) and spinach Ni concentration (54–77%) in Ni-treated soil. The biochars produced at 550 °C were more effective at reducing Ni mobility and Ni uptake by spinach than those produced at 350 °C, attributed to higher CaCO₃ and lower acidic functional group content, which resulted in greater enhancement of soil pH. When comparing the biochars produced at the same temperature, the rice husk biochars were the most effective in reducing Ni bioavailability, likely due to their lower acidic functional group content and higher nano-silica content which resulted in higher soil pH values and potentially promoted the formation of Ni-silicates and hydroxides.

Abbreviations : Ni: Nickel; RHB: rice husk biochar; LRB: licorice root pulp biochar; WsEx: water soluble and exchangeable; CARB: carbonate form; RES: residual; MnOx; manganese oxides bound; AFeOx; amorphous iron oxides bound; CFeOx: crystalline iron oxides bound; OM: organic bound.     

不同种类生物质炭对植烟土壤保育及烤烟生长和品质的影响

通过盆栽试验,研究施加等量(3%)椰壳炭、竹炭、猪炭和烟秆炭对植烟土壤基本理化性质、土壤养分、烤烟生长状况以及烤烟常规化学成分的影响。结果表明:施用生物质炭对土壤电导率、有效养分含量、有机碳含量和酶活性有显著影响,其中施用竹炭后土壤有机碳含量较CK增幅最大,达146.37%;而施加猪炭能显著提高植烟土壤中电导率、有效磷、速效钾含量以及过氧化氢酶和脲酶的活性(p0.05)。生物质炭对烤烟农艺性状的影响较小,仅在猪炭处理下,烤烟茎围较对照增加0.78cm。施用生物质炭能显著提高烤烟的生物量(p0.05),其中猪炭和烟秆炭处理下烤烟叶片干质量较CK分别提高了58.07%和47.01%。另外,在施用竹炭、猪炭和烟秆炭后,烤烟叶片中烟碱、总氮、还原糖和钾均处于优质烟叶适宜范围内。猪炭处理还可以显著提高烟叶氯含量(p0.05),并使烤后烟叶糖碱比和氮碱比达到优质烟叶标准。综上所述,在各类生物质炭中,施用猪炭和烟秆炭对于改善植烟土壤理化性质和养分状况、提高烤烟产量和品质的效果较好。     

Biochar-induced changes in soil properties affected immobilization/mobilization of metals/metalloids in contaminated soils

Purpose

Remediation of metal contaminated soil with biochar is attracting extensive interest in recent years. Understanding the significance of variable biochar properties and soil types helps elucidating the meticulous roles of biochar in immobilizing/mobilizing metals/metalloids in contaminated soils.

Materials and methods

Six biochars were produced from widely available agricultural wastes (i.e., soybean stover, peanut shells and pine needles) at two pyrolysis temperatures of 300 and 700 °C, respectively. The Pb-, Cu-, and Sb-contaminated shooting range soils and Pb-, Zn-, and As-contaminated agricultural soils were amended with the produced biochars. The mobility of metals/metalloids was assessed by the standard batch leaching test, principal component analysis and speciation modeling.

Results and discussion

The changes in soil properties were correlated to feedstock types and pyrolysis temperatures of biochars based on the principal component analysis. Biochars produced at 300 °C were more efficient in decreasing Pb and Cu mobility (>93 %) in alkaline shooting range soil via surface complexation with carboxyl groups and Fe-/Al-minerals of biochars as well as metal-phosphates precipitation. By contrast, biochars produced at 700 °C outperformed their counterparts in decreasing Pb and Zn mobility (100 %) in acidic agricultural soil by metal-hydroxides precipitation due to biochar-induced pH increase. However, Sb and As mobility in both soils was unfavorably increased by biochar amendment, possibly due to the enhanced electrostatic repulsion and competition with phosphate.

Conclusions

It is noteworthy that the application of biochars is not equally effective in immobilizing metals or mobilizing metalloids in different soils. We should apply biochar to multi-metal contaminated soil with great caution and tailor biochar production for achieving desired outcome and avoiding adverse impact on soil ecosystem.

     

Combined effect of biochar and soil moisture on soil chemical properties and microbial community composition in microplastic-contaminated agricultural soil

Accumulation of microplastics (MPs) in agricultural environments has caused growing concern in recent years because of its detrimental impacts on soil quality, crop productivity and ecosystem function. This study was conducted to assess the impact of biochar on soil chemical and microbial properties in a MP-contaminated soil under two moisture regimes. Soil was contaminated with 1% (w/w) of low-density polyethylene MPs. Four types of standard biochar, that is, oil seed rape (OSR) biochar produced at 550°C (OSR 550) and 700°C (OSR 700) and soft wood pellet (SWP) biochar produced at 550°C (SWP 550) and 700°C (SWP 700), were applied at a rate of 5% (w/w). The control was maintained without MP addition. The samples were incubated in soil with two moisture regimes, that is, at 30% and 70% of the water holding capacity, and the soil chemical and microbiological properties were assessed after 100 days of incubation. OSR biochar application significantly increased soil pH (8.53–8.81) and electrical conductivity (0.51–0.58 dS/m) in both moisture regimes. The effect of biochar application on soil enzyme activity and microbial community composition did not show a clear trend. However, SWP 700 biochar improved soil enzyme activity compared with that of the control and improved bacterial diversity and evenness compared with those of other biochars, which was attributed to the high surface area available for microbial colonization. Low soil moisture content significantly reduced enzyme activity and bacterial richness even with biochar amendment, except for SWP 550 biochar. This study implies the suitability of biochar for improvement of soil quality in MP contaminated soil under both moisture regimes. However, further long-term studies are needed to get a clear understanding on the impact of different types of biochar on MP-contaminated soil.     

生物炭对铜矿区污染土壤微生物活性及香根草富集铜、镉、铅的影响

矿区土壤易发生重金属污染,是土地资源利用和维护的一大难题。以铜矿区污染土壤为研究对象,按质量比添加0,1%,2%,4%,10% (w/w)的生物炭,进行香根草室内盆栽试验。研究添加生物炭对土壤pH和微生物活性、香根草富集与转运重金属的影响,探明重金属形态含量与生物炭、微生物活性的相关性,旨在为生物炭与香根草联合修复矿区重金属污染土壤提供理论参考。结果表明:生物炭的添加能提高土壤pH,显著提高土壤FDA水解酶、蔗糖酶和脲酶活性,显著促进土壤基础呼吸,但对土壤微生物量碳无显著影响;生物炭的添加使香根草生物量显著增大,降低土壤Cu和Pb的有效态占比,Cd的变化与此相反;添加生物炭促进香根草对Cd和Pb的富集,降低香根草对Cu的富集,减少Cu、Cd和Pb在香根草体内的转运,因此香根草可作为Cu、Cd和Pb的稳定化植物。土壤蔗糖酶活性与香根草叶片Cu、Cd和Pb含量、有效态和残渣态Cu含量呈显著正相关,土壤基础呼吸与叶片Cu、Cd和Pb含量、有效态Cu、Pb含量呈显著负相关,而与有效态Cd含量呈显著正相关。总之,生物炭可减弱矿区土壤重金属对香根草生长的毒害作用,并促进香根草对重金属的富集,两者结合可改善铜矿区污染土壤的理化性质和微生物活性,有利于重金属污染土壤修复,改善土壤质量。     

镉污染水稻秸秆生物炭对土壤中镉稳定性的影响

中国农田土壤镉等重金属污染问题突出,对其生产过程中产生的镉污染水稻秸秆进行无害化和资源化利用研究具有重要意义。该研究通过连续提取试验、风险评价指数法、吸附动力学/热力学、土柱试验,以及X射线衍射分析、傅里叶变换红外光谱分析等手段,探究了不同热解温度下制备的镉污染水稻秸秆生物炭对土壤中Cd的稳定特性。研究结果表明,镉污染水稻秸秆热解制备的生物炭可有效吸附土壤镉。热解温度显著影响生物炭对Cd的吸附能力（P<0.05）,高温生物炭对Cd吸附容量大,700 ℃下制备的生物炭对Cd的吸附容量可达72.57 mg/g。生物炭对Cd的吸附主要通过含氧官能团表面络合和碳酸盐共沉淀吸附,其吸附过程符合Langmuir方程和准二级动力学模型,吸附过程受化学速率控制。土柱试验表明,镉污染水稻秸秆生物炭能有效降低土壤Cd的下渗迁移能力,其作用机制主要是将土壤Cd从酸可提取态转化为残渣态,施入高温生物炭的土壤中Cd的残渣态比例最高。上述结果表明,热解可有效处理镉污染水稻秸秆,制备的生物炭可用于Cd等重金属污染土壤的稳定修复,有效解决镉污染水稻秸秆的潜在二次污染问题并实现其安全利用。     

Effects of biochars derived from different feedstocks and pyrolysis temperatures on soil physical and hydraulic properties

Purpose

Biochar addition to soils potentially affects various soil properties, and these effects are dependent on biochars derived from different feedstock materials and pyrolysis processes. The objective of this study was to investigate the effects of amendment of different biochars on soil physical and hydraulic properties.

Materials and methods

Biochars were produced with dairy manure and woodchip at temperatures of 300, 500, and 700 °C, respectively. Each biochar was mixed at 5 % (w/w) with a forest soil, and the mixture was incubated for 180 days, during which soil physical and hydraulic properties were measured.

Results and discussion

Results showed that the biochar addition significantly enhanced the formation of soil macroaggregates at the early incubation time. The biochar application significantly reduced soil bulk density, increased the amount of soil organic matter, and stimulated microbial activity at the early incubation stage. Saturated hydraulic conductivities of the soil with biochars, especially produced at high pyrolysis temperature, were higher than those without biochars on the sampling days. The treatments with woodchip biochars resulted in higher saturated hydraulic conductivities than the dairy manure biochar treatments. Biochar applications improved water retention capacity, with stronger effects by biochars produced at higher pyrolysis temperatures. At the same suction, the soil with woodchip biochars possessed higher water content than that with the dairy manure biochars.

Conclusions

Biochar addition significantly affected the soil physical and hydraulic properties. The effects were different with biochars derived from different feedstock materials and pyrolysis temperatures.     

Microbial biomass growth,following incorporation of biochars produced at 350 °C or 700 °C,in a silty-clay loam soil of high and low pH

Biochar has been widely proposed as a soil amendment, with reports of benefits to soil physical, chemical and biological properties. To quantify the changes in soil microbial biomass and to understand the mechanisms involved, two biochars were prepared at 350 °C (BC350) and 700 °C (BC700) from Miscanthus giganteus, a C4 plant, naturally enriched with ¹³C. The biochars were added to soils of about pH 4 and 8, which were both sampled from a soil pH gradient of the same soil type. Isotopic (¹³C) techniques were used to investigate biochar C availability to the biomass. Scanning Electron Microscopy (SEM) was used to observe the microbial colonization, and Attenuated Total Reflectance (ATR) to highlight structural changes at the surface of the biochars. After 90 days incubation, BC350 significantly increased the biomass C concentration relative to the controls in both the low (p < 0.05) and high pH soil (p < 0.01). It declined between day 90 and 180. The same trend occurred with soil microbial ATP. Overall, biomass C and ATP concentrations were closely correlated over all treatments (R² = 0.87). This indicates that neither the biomass C, nor ATP analyses were affected by the biochars, unless, of course, they were both affected in the same way, which is highly unlikely. About 20% of microbial biomass ¹³C was derived from BC350 after 90 days of incubation in both low and high pH soils. However, less than 2% of biomass ¹³C was derived from BC700 in the high pH soil, showing very low biological availability of BC700. After 90 days of incubation, microbial colonization in the charsphere (defined here as the interface between soil and biochar) was more pronounced with the BC350 in the low pH soil. This was consistent with the biomass C and ATP results. The microbial colonization following biochar addition in our study was mainly attributed to biochar C availability and its large surface area. There was a close linear relationship between ¹³CO₂ evolved and biomass ¹³C, suggesting that biochar mineralization is essentially a biological process. The interactions between non-living and living organic C forms, which are vital in terms of soil fertility and the global C cycle, may be favoured in the charsphere, which has unique properties, distinct from both the internal biochar and the bulk soil.     

Short-term effects of raw rice straw and its derived biochar on greenhouse gas emission in five typical soils in China

Abstract

A short-term study was conducted to investigate the greenhouse gas emissions in five typical soils under two crop residue management practices: raw rice straw (Oryza sativa L., cv) and its derived biochar application. Rice straw and its derived biochar (two biochars, produced at 350 and 500°C and referred to as BC350 and BC500, respectively) were incubated with the soils at a 5% (weight/weight) rate and under 70% water holding capacity for 28 d. Incorporation of BC500 into soils reduced carbon dioxide (CO₂) and nitrous oxide (N₂O) emission in all five soils by 4?40% and 62?98%, respectively, compared to the untreated soils, whereas methane (CH₄) emission was elevated by up to about 2 times. Contrary to the biochars, direct return of the straw to soil reduced CH₄ emission by 22?69%, whereas CO₂ increased by 4 to 34 times. For N₂O emission, return of rice straw to soil reduced it by over 80% in two soils, while it increased by up to 14 times in other three soils. When all three greenhouse gases were normalized on the CO₂ basis, the global warming potential in all treatments followed the order of straw > BC350 > control > BC500 in all five soils. The results indicated that turning rice straw into biochar followed by its incorporation into soil was an effective measure for reducing soil greenhouse gas emission, and the effectiveness increased with increasing biochar production temperature, whereas direct return of straw to soil enhanced soil greenhouse gas emissions.     

Benefits of Biochars and NPK Fertilizers for Soil Quality and Growth of Cowpea (Vigna unguiculata L. Walp.) in an Acid Arenosol

Fertilization is required for optimum plant growth, particularly in unfertile soils, while optimizing nutrient use efficiency is an alternative to reduce inorganic fertilizer needs and reduce environmental problems caused by nutrient leaching. This study investigated soil properties and cowpea yield responses to biochars (BCs) made from different feedstocks, baby corn peel biochar (BC1), branches of mango tree biochar (BC2), and rice husk biochar (BC3), applied in combination with nitrogen-phosphorus-potassium (NPK) fertilizers. The experiment was conducted in a greenhouse, using an acid sandy soil (Arenosol) that was submitted for 70 d to the following eight treatments:i) control; ii) full dose of NPK (a commercial compound fertilizer (12-24-12 of N-P₂O₅-K₂O) + urea (46% N)); iii) BC1 + half dose of NPK; iv) BC1 + full dose of NPK; v) BC2 + half dose of NPK; vi) BC2 + full dose of NPK; vii) BC3 + half dose of NPK; and viii) BC3 + full dose of NPK. All biochars were applied at a rate of 0.9% (weight/weight), and each type of biochar was combined with half and full doses of NPK fertilizers. Soil pH increased significantly (P < 0.05) in treatments with BC1 and BC2, while cation exchange capacity (CEC) and available P were higher in the treatments with BC1; BC1 and BC2 also induced higher activity of enzymes related to the P cycle and higher cowpea yield. Similar soil properties and cowpea yield parameters were obtained with the full and half doses of NPK fertilizers for each type of biochar used. In conclusion, biochars in the combination with NPK fertilizers improved soil chemistry and enzymatic activities, allowing reduced fertilizer application and food production costs in the acid soil studied.     

生物质炭对不同pH值土壤矿质氮含量的影响

为了揭示生物质炭作为土壤调理剂添加后对土壤矿质氮形态、含量等土壤性质的影响,该研究利用芒草分别在350和700℃裂解制得生物质炭,发现2个温度尤其是700℃制得的生物质炭,对NH4+有很强的吸附能力,但对NO3-的吸附能力很弱。将生物质炭分别加入到酸性(pH值为3.8)和碱性(pH值为7.6)土壤中,25℃下室内培养180d。结果表明,生物质炭提高了土壤全氮含量,酸性和碱性土壤分别平均提高了22%和17%;但使土壤铵态氮含量大幅降低至接近仪器检测限水平;生物质炭对土壤硝态氮含量的影响因生物质炭和土壤类型而异。生物质炭对土壤矿质氮形态和含量的影响,显然与生物质炭对铵的吸附作用、提高土壤pH值、增强氨挥发损失,以及形成微生物量氮等密切相关。该研究可为开展生物质炭基氮素新型肥料及制剂等方面的科学研究提供参考。     

皇竹草生物炭的结构特征及其对（）的吸附性能

以皇竹草茎秆为原料,在限氧控温（300、500、700℃）条件下制备生物炭,研究该生物炭的结构特征及其对Cr（Ⅵ）的吸附行为。结果发现,随着热解温度的升高,皇竹草生物炭的产率下降,而灰分、pH呈上升趋势;电镜扫描（SEM）观察可见不同热解温度下所制备的生物炭结构相似,均具多孔和管状结构,但在700℃条件下所制备的生物炭相对300℃下制备的生物炭孔壁变薄,且孔壁有附着物,切面有突起结构。三种温度下制备的皇竹草生物炭对溶液中的Cr（Ⅵ）都具有较好的吸附作用,且500、700℃下制备的生物炭比300℃下制备的生物炭具有更好的吸附效果。在0~1 h之间,三种热解温度下制备的生物炭对铬的吸附量均随着时间的延长而快速增加,当吸附至1h时,基本达到饱和状态,随后吸附量无明显变化。     

The potential feasibility for soil improvement, based on the properties of biochars pyrolyzed from different feedstocks

Purpose

Biochars have been considered as useful soil amendments due to their beneficial properties in improving soil fertility, carbon (C) sequestration, and soil decontamination. In our study, a series of biochars produced from different types of feedstocks at two pyrolysis temperatures (300 and 500 °C) were characterized to evaluate their different potentials as soil amendments.

Materials and methods

Ten types of feedstocks were used to prepare biochars at the pyrolysis temperatures of 300 and 500 °C, for 2 h. Chemical and physical analyses, X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier Transform Infrared (FTIR) analyses were conducted to determine differences in biochar properties. Then, soil incubation studies were used to investigate the relationships between these biochar properties and their different ameliorant values in soil.

Results and discussion

The pH, ash, total C, total potassium, total phosphorus, total base cation concentrations, surface areas, and total pore volumes of biochars produced at 500 °C were higher than at 300 °C, while the reverse applied for yields, total oxygen and total hydrogen, and average pore widths and particle sizes. Cluster analysis suggested that biochars derived from similar feedstock types belonged in the same category. The SEM, XRD, and FTIR analyses of typical biochars from the different categories suggested both variations and similarities in their characteristics. In addition, the results from soil incubation experiments were consistent with the conclusions made from biochar characteristics analysis.

Conclusions

Biochars derived from swine manures, fruit peels, and leaves with high pH and macro-nutrients appeared appropriate to increase soil pH and soil nutrient availability; whereas, biochars from wetland plant residues with high C concentrations and Brunauer–Emmett–Teller were better for soil C sequestration and contaminant adsorption.     

Application of Biochar and Compost for Enhancement of Rice (Oryza Sativa L.) Grain Yield in Calcareous Sandy Soil

The application of compost to calcareous soils by farmers is a well-established practice and has been shown to improve yields. However, incorporation of biochar and mixture of biochar and compost into calcareous soils is a relatively novel concept for improving soil quality and yield since calcareous soils comprise a large scale of soils worldwide. The objective of this study was to determine the effects of the co-application of biochar and compost on the soil properties, nutrient status and grain yield of rice in calcareous sandy soil. The experiment was conducted in a factorial arrangement based on randomized complete block design with three replications. The compost application rates were 1% and 3% (w/w; compost/soil) and the applied rates of biochars (rice straw biochar, RSB; sugarcane bagasse biochar, SBB) were 0.3% and 0.9% (w/w; biochar/soil). The results showed that soil pH decreased with increasing application rates of either compost or biochars. However, soil EC was enhanced through increasing the application rates of compost and biochars. The co-application of biochar and compost improved soil total N and available P concentrations. The soil available K increased with increasing the rate of incorporated biochars and compost. An increase of soil available K was more predominate with the application of RSB than SBB. The RSB, also, added a considerable amount of silicon (Si) to the soil. The co-incorporation of biochars and compost enhanced soil available concentrations of Fe, Zn, Cu, and Mn as well. The RSB was more effective than the SBB in grain yield enhancement almost certainly due to a higher Si content in RSB. Furthermore, the concurrent application of biochars and compost increased grain yield more than applying them individually. A higher application rate of biochar and compost induced a higher grain yield. The co-application of highest rates of RSB (0.9%) and compost (3%) induced the highest grain yield (26.1 g/pot) among the treatments. The increase in yield compare to the control were 321% and 260% for 0.9% RSB + 3% compost and 0.9% SBB + 3% compost, respectively. The increase in the grain yield was due to an improvement in the soil chemical properties and nutrients enhancement. Finally, the co-application of the highest rate of RSB (0.9%) and compost (3%) is recommended to obtain the appropriate rate of rice grain yield in calcareous sandy soil.     

生物炭固定解鸟氨酸拉乌尔菌对紫色土磷钾有效性的影响

筛选能为解鸟氨酸拉乌尔菌（Raoultella ornithinolytica,Ro）提供适宜生存空间的生物炭,探讨固定Ro的生物炭对不同性质紫色土磷（P）钾（K）有效性的影响。采用限氧裂解法分别在不同温度（300 ℃、500 ℃和700 ℃）和原材料下（玉米秆、小麦秆和稻壳）制备生物炭。利用噻唑蓝（MTT）比色法筛选固定载体,通过傅立叶变换衰减全反射红外光谱法（ATR-FTIR）表征其性能和结构;采用室内土培试验探讨单施生物炭（BC）、Ro及固定Ro的生物炭（Ro-BC）对不同性质紫色土速效磷钾的影响。MTT结果表明,以热解温度500 ℃的玉米秸秆炭（MSC500）为最佳载体;红外光谱结果显示,500 ℃玉米秸秆炭表面官能团的C=C和－OH的伸缩振动峰较明显,C－O－C键伸缩振动峰加宽变深;室内培养试验表明,施入Ro和Ro-BC均可显著提高酸性、中性和石灰性紫色土速效磷、速效钾含量和细菌数量。以Ro-BC对土壤速效磷和细菌数量的提升效果最好,提升效果分别达61.1% ~ 276.3%和22.8% ~ 82.5%。但培养至168 h时,速效磷出现下降趋势;对速效钾而言,酸性紫色土以Ro处理对其提升效果最好（46.3%）,中性和石灰性紫色土则以Ro-BC处理提升效果最好（29.8%和71.23%）,针对不同Ro筛选适宜的固定载体可提高Ro菌株活性,改善土壤微环境,进而有助于提高土壤磷钾有效性。     

Responses of Soil Microbial Community Structure and Activity to Incorporation of Straws and Straw Biochars and Their Effects on Soil Respiration and Soil Organic Carbon Turnover

Like straw, biochar incorporation can influence soil microorganisms and enzyme activities and soil carbon(C) responses; however,few studies have compared the various effects of straw and biochar and the underlying mechanisms. An experiment was performed to study the changes in soil respiration(SR) and soil organic C(SOC) fluxes in response to the incorporation of three kinds of straw(reed, smooth cordgrass, and rice) and their pyrolyzed products(biochars) at Chongming Island, China. In addition, the microbial activity and community structure of some amended soils were also analyzed to clarify the mechanisms of these responses. The results showed that all biochar incorporation(BC) induced lower SR than the corresponding unpyrolyzed straw incorporation(ST), and the average SR in the soils following BC and ST during the experimental periods was 21.69 and 65.32 μmol CO_2 m~(-2)s~(-1), respectively.Furthermore, the average SOC content was 16.97 g kg~(-1) following BC, which was higher than that(13.71 g kg~(-1)) following ST,indicating that compared to ST, BC was a low-C strategy, even after accounting for the C loss during biochar production. Among the BC treatments, reed-BC induced the lowest SR(17.04 μmol CO_2 m~(-2)s~(-1)), whereas smooth cordgrass-BC induced the highest SR(27.02 μmol CO_2 m~(-2)s~(-1)). Furthermore, in contrast with ST, BC significantly increased the abundance of some bacteria with poorer mineralization or better humification ability, which led to lower SR. The lower easily oxidizable C(EOC) and higher total C contents of biochars induced lower SR and higher SOC in the soil following BC compared to that following ST. Among the BC treatments,the higher total nitrogen content of rice biochar led to significantly higher soil microbial biomass, and the lower EOC content of reed biochar led to lower soil microbial activity and SR.     

Sugarcane bagasse biochars impact respiration and greenhouse gas emissions from a latosol

Purpose

A paucity in knowledge remains on the influence of biochar production temperature and the rate of application on greenhouse gas emissions from soil. The objective of this column experiment was to evaluate a biochar thermosequence by doses on CO₂, N₂O, and CH₄ emissions from a latosol following nitrogen fertilizer application following a pre-incubation period.

Materials and methods

Biochar was produced from sugarcane bagasse pyrolyzed at 300, 500, and 700 °C (BC 300, BC 500, and BC 700, respectively). Biochars were added to air-dried latosol columns at rates of 0, 0.5, 1, 2, 5, 10, and 15 % (w/w), and the water content was brought to 95 % of water-filled pore space (WFPS). The emissions from columns were tested on days 1, 3, 7, 15, and 30 following a 30-day pre-incubation.

Results and discussion

All treatments showed a decrease in respiration across the study period. The higher doses of biochar of BC 300 and BC 700 resulted in significantly higher respiration than controls on days 15 and 30. Neither biochar dose nor temperature had a significant effect on CH₄ emissions during the study period. Application of all biochars suppressed the emissions of N₂O at all doses on days 1 and 3, compared to the control. N₂O emissions from higher temperature biochar-amended soil at 2, 5, 10, and 15 % were greater than that from corresponding treatments of lower-temperature biochar-amended soil on days 15 and 30.

Conclusions

Soil respiration and overall greenhouse gas emission from latosol increased with biochar dose and pyrolysis temperature in the 30-day study period due to increasing water retention facilitated by biochar. Careful consideration is needed when applying bagasse biochar as it changes N cycling and soil physical properties.

     

生物质炭中的污染物含量及其田间施用的环境风险预测

生物质炭在碳固定、污染修复和酸性土壤改良中的应用非常广泛,但对生物质炭中所含污染物的研究甚少,其在田间应用中的环境风险并不清楚。该文选择松针和麦秆为原料,采用不同制备方法,研究了不同条件下获得的生物质炭中的重金属和多环芳烃含量,并初步评估了其田间应用的环境风险。研究表明,不同有机废弃物来源制备的生物质炭中均含有一定量的重金属(0.301～128mg/kg)和多环芳烃(1.48～5.48mg/kg);松针制备的生物质炭中的重金属含量普遍高于麦秆制备的生物质炭,而多环芳烃含量则相反,且高温制备有助于降低生物质炭中的多环芳烃含量;在低施用量的田间条件下,生物质炭的施用不易对土壤造成多环芳烃的环境风险,但在高施用量条件下,生物质炭中含有的多环芳烃容易使土壤中多环芳烃含量达到中度或重度污染的程度;生物质炭中的重金属在土壤中的积累量比较有限,环境风险较小。