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SEM photomicrograph of microbial colonization on the surface of biochar at 90 days of incubation. A scale: a) Bar ¼ 10 mm, b) Bar ¼ 5 mm, c) Bar ¼ 10 mm, d) Bar ¼ 10 mm, e) Bar ¼ 10 mm, f) Bar ¼ 5 mm, g) Bar ¼ 10 mm, h) Bar ¼ 5 mm. Biochar350 in low pH low soil without (a) and with (b) ryegrass. Biochar700 in low pH low soil, without (c) and with (d) ryegrass. Biochar350 in high pH high soil, without (e) and with (f) ryegrass. Biochar700 in pH high soil, without (g) and with (h) ryegrass.  

SEM photomicrograph of microbial colonization on the surface of biochar at 90 days of incubation. A scale: a) Bar ¼ 10 mm, b) Bar ¼ 5 mm, c) Bar ¼ 10 mm, d) Bar ¼ 10 mm, e) Bar ¼ 10 mm, f) Bar ¼ 5 mm, g) Bar ¼ 10 mm, h) Bar ¼ 5 mm. Biochar350 in low pH low soil without (a) and with (b) ryegrass. Biochar700 in low pH low soil, without (c) and with (d) ryegrass. Biochar350 in high pH high soil, without (e) and with (f) ryegrass. Biochar700 in pH high soil, without (g) and with (h) ryegrass.  

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Article
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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 wi...

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... Electron Microscopy (SEM) showed that the Mis- canthus cell structure was largely intact after pyrolysis, albeit apparently consisting of partially carbonised structural material. Microbial colonization after 90 days on the surfaces of BC350 and BC700 is shown in Fig. 3. Biochar350 was heavily colonized with bacteria and fungi in all treatments. These results were consistent with the measured increases in biomass C and ATP with biochar350 addition (Fig. 1). No microbial colonization of BC700 was observed in the high pH soil (Fig. 3) but, in the low pH soil, numerous fungal hyphae were detected on the ...
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... colonization after 90 days on the surfaces of BC350 and BC700 is shown in Fig. 3. Biochar350 was heavily colonized with bacteria and fungi in all treatments. These results were consistent with the measured increases in biomass C and ATP with biochar350 addition (Fig. 1). No microbial colonization of BC700 was observed in the high pH soil (Fig. 3) but, in the low pH soil, numerous fungal hyphae were detected on the surface of BC700. After 180 days of incubation, no bacterial cells were observed (SEM electron micro- graphs not shown) in this treatment. More colonization images by SEM are given in supplementary ...
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... results are consistent with the SEM data which showed no colonization of BC700 in the high pH soil (Figs. 1 and 3). Ryegrass addition increased the biochar derived biomass C in all biochar amended soils, except in the low pH soil amended with BC700 (Fig. 4). ...
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... increase in microbial colonization was observed in the high pH soil with BC700 addition, compared to BC350 (Figs. 1 and 3). This might be because the availability of C, N and other nutrients were low in BC700, as most were lost during pyrolysis (Table 1). ...
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... toxic to biomass C resulting in less biomass C and ATP (Fig. 1). However, in the low pH soil, microbial biomass C was little affected (7% less at day 90 but 8% more at day 180, and ATP even increased by 22% and 38% at day 90 and 180, respectively). This was also consistent with the parallel microbial colonization observed by SEM at day 90 ( Fig. 3) and the biochar derived biomass C synthesised (Fig. 4). It is not clear why BC700 caused such a drastic decrease in biomass in the high pH soil, while the biomass increased in the low pH soil (Fig. 1). Microorganisms are very sensitive to changes in soil pH, which can change the microbial biomass, activity and community structure ...
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... Warnock et al. (2010) observed decreased of Arbuscular Mycorrhizal (AM) fungi following biochar addition to a soil with an initial pH of 7.9, and suggested that there might be mechanisms involved other than direct pH effects. In our study, the pH increase caused by addition of BC700 could only explain the biomass C increase in the low pH soil (Figs. 1, 3 and 4). This also confirms our hypothesis that the pH increase caused by BC700 mainly stimulates microbial production in low pH but not high pH soils. ...
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... are affected by the changes in the soil microenvironment following biochar addition, clearly, bio- char mineralization is also largely controlled by the microbial biomass. Furthermore, in a biochar amended soil, the fresh organic matter inputs (e.g. plant residues or root exudates) are likely to interact with microorganisms in the charsphere (Figs. 3 and 7). Biomass C and ATP increased with ryegrass addition (Fig. 1) and the biochar derived biomass C concentration was increased with ryegrass (Fig. 4). This means that, in addition to the C and nutrients provided by biochar alone, the extra C and energy available to the biomass from the ryegrass enabled more efficient synthesis of bio- char ...

Citations

... However, biochar enhances soil microbial habitat by increasing surface area or porosity and improves soil nutrient availability by providing essential mineral nutrients. Biochar application to soil will provide soil microorganisms with a certain amount of readily decomposable carbon from biochar itself (Luo et al., 2013). It will promote the co-metabolism of soil microorganisms, increase the biomass and activity of soil microorganisms, and enhance soil respiration and enzyme activity, thus significantly increasing the rate of mineralization of soil organic carbon (Hamer et al., 2004). ...
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Biochar with a higher total phosphorus concentration (⩾1.0%), total carbon concentration (⩾70%), and specific surface area (⩾50 m2 g−1) were optimal for improving crop yields. Greater yield increases were observed in the soil with acidic, sandy or clay soils than alkaline or loam soils. The addition of biochar boosted crop yields in low-fertility soils. Biochar application to soil improved the soil quality by increasing soil organic carbon, total N, and pH, while decreasing soil bulk density. Biochar has been widely used for soil improvement, but uncertain results persist due to diverse biochar characteristics, soil properties, and crop responses. Therefore, the effects of biochar on crop yields and soil quality were evaluated using effect size method from 1 011 paired data points from field trials, based on a global meta-analysis method. The results indicated that biochar with a higher total phosphorus concentration (⩾1.0%), total carbon concentration (⩾70%), and specific surface area (⩾50 m2 g−1) were optimal for improving crop yields. For improving crop yields, biochar made from manure (effect size, 42%) outperformed that made from ligneous (22%) or cereal (12%) material. Porous, acidic, or young soil types were optimal for biochar application, while sandy and clay soils were preferred over loam soil. Soils with lower available nitrogen (<80 mg kg−1), phosphorus (<10 mg kg−1), potassium (<120 mg kg−1), pH (<4.5), and cation exchange capacity (<10 cmol kg−1) were more effective on crop yield increases. The effect of biochar on yield was higher for cash crops (oil plants: 37%, vegetables: 28%) compared to food crops (legumes: 26%, maize: 20%, wheat: 12%, rice: 6%), but with no significant effect observed on rice (P=0.788). Finally, biochar increases crop yields by improving soil quality through enhanced levels of soil organic carbon, total nitrogen, ammonium-nitrogen, nitrate-nitrogen, and soil pH while reducing soil bulk density. Our research enhances understanding of the relationships between biochar, soil, and crops, aiding researchers, manufacturers, and farmers in making informed decisions regarding biochar selection, planting locations, and crop choices.
... This immediate shortterm increase in CO 2 production after biochar addition is common and mainly attributed to the presence of labile C fraction in biochar, which fuels the microbes in the short term (Maestrini et al. 2015). Previous studies also observed increased short-term mineralization of SOC immediately after biochar addition, but this positive priming decreased over time (Luo et al. 2013;Singh and Cowie 2014). However, similar 13 C signatures of soil and biochar in this study did not allow us to separate the proportion from which this CO 2 production originated (soil or biochar). ...
... However, in the longer term, part or most of the added glucose would have been desorbed and consumed by soil microorganisms. Our results agree with the concept that biochar usually benefits microbial growth and activity because of the supply of labile C present in biochar (Luo et al. 2013;Farrell et al. 2013) as well as serving as the preferred microbial habitat in its large and porous surface matrix (Pietikäinen et al. 2000;Lehmann et al. 2011). The increased microbial biomass and CUE of glucose in biochar-amended soil (especially in the higher biochar application rate treatments) suggest that the added glucose might have been effectively and/or preferentially used by soil microorganisms to synthesize new biomass. ...
Article
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Biochar has been widely recognized for its potential to increase carbon (C) sequestration and mitigate climate change. This potential is affected by how biochar interacts with native soil organic carbon (SOC) and fresh organic substrates added to soil. However, only a few studies have been conducted to understand this interaction. To fill this knowledge gap, we conducted a 13C-glucose labelling soil incubation for 6 months using fine-textured agricultural soil (Stagnosol) with two different biochar amounts. Biochar addition reduced the mineralization of SOC and 13C-glucose and increased soil microbial biomass carbon (MBC) and microbial carbon use efficiency (CUE). The effects were found to be additive i.e., higher biochar application rate resulted in lower mineralization of SOC and 13C-glucose. Additionally, soil density fractionation after 6 months revealed that most of the added biochar particles were recovered in free particulate organic matter (POM) fraction. Biochar also increased the retention of 13C in free POM fraction, indicating that added 13C-glucose was preserved within the biochar particles. The measurement of 13C from the total amino sugar fraction extracted from the biochar particles suggested that biochar increased the microbial uptake of added 13C-glucose and after they died, the dead microbial residues (necromass) accumulated inside biochar pores. Biochar also increased the proportion of occluded POM, demonstrating that increased soil occlusion following biochar addition reduced SOC mineralization. Overall, the study demonstrates the additional C sequestering potential of biochar by inducing negative priming of native SOC as well as increasing CUE, resulting in the formation and stabilization of microbial necromass.
... We conducted our investigation by focusing on the biotic zone referred to as the charosphere. The charosphere is a concept analogous to the rhizosphere and is defined as the distinct area surrounding each fragment of biochar [8,9]. Yu, M.J. [10] investigated the distribution of functional genes associated with soil nitrogen cycling within the charosphere across multiple profile gradients, thereby enhancing the understanding of the charosphere's definition, including its size, properties, functional scope, and impact on soil processes. ...
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This study employs a soil-biochar-soil sandwich model to investigate phosphorus and cadmium transport mechanisms at the biochar-soil interface. Utilizing DGT-CID technology, we found phosphorus and cadmium exhibit gradient diffusion, with biochar as the diffusion center. Biochar significantly increased soil effective phosphorus concentration by 7-fold (p < 0.05) through sustained release. Cadmium concentration increased from 7.11 mg/L to 10.09 mg/L, with a concentration jump at the interface, indicating aggregation and transfer towards the biochar layer. Theoretical calculations show that the transport fluxes of phosphorus and cadmium at the interface were 0.94 mg/L and 0.75 mg/L, respectively. Our findings clarify the distribution and transport fluxes of these elements at the biochar-soil interface.
... They found that biochar application at 1% and 3% increased the CEC of sandy loam soil by 20% and 30%, while the comparable increases for clay soil were 9% and 19%, respectively. Similarly, Luo et al. (2013) used three levels of biochar to improve the properties and productivity of degraded soil and found an increase in CEC at all doses (up to 17.3%) compared to the control (2.72 cmol kg -1 ) with CEC values of 3.03, 3.19, and 3.15 cmol kg -1 for biochar applications of 1.5, 5, and 10%, respectively. Increasing the dose of biochar also increases the total porosity of the soil proportionally (Liu et al., 2020), resulting in a decrease in soil density and an increase in the infiltration rate (Herath et al., 2013). ...
... This enhancement is likely a result of improved soil aeration and increased supply and availability of labile C, as well as the slow release of N nutrient induced by the biochar particles (Awad et al., 2018;Dong et al., 2020;Zhang et al., 2023). Consequently, these improved conditions provide a more favorable habitat for methanotrophs (Luo et al., 2013;Lafuente et al., 2019;Pascual et al., 2020). Furthermore, our study revealed that biochar-based urea elevates both soil CH 4 uptake and oxidation rates, while leaving CH 4 production rates unaffected. ...
... Extensive colonization of BC that has undergone centuries of natural aging has been well documented; however, the successful colonization by soil organisms within relatively short periods (i.e., several years) remains unclear. Wood BC, due to its limited labile (easily degradable) carbon, experiences sparse microbial colonization even after 3 years of outdoor aging (Luo et al. 2013). This limited colonization occurs because soil microorganisms require readily available carbon for growth, which BC lacks. ...
Article
Biochar (BC), a carbon‐dense substance created through the pyrolysis of organic biomass, has garnered considerable interest as a promising option for sustainable mitigation methods. A comprehensive examination of the diverse attributes of BC and its implications for addressing contemporary environmental issues while fostering sustainable practices is compiled in this review. The synthesis techniques and structural attributes of BC are scrutinized initially, emphasizing its remarkable features such as broad surface area, porosity, and active sites. These characteristics of BC are conducive to myriad environmental applications, including pollutant remediation, soil health enhancement, and carbon sequestration. Subsequently, this review delves into the mechanisms underlying BC's effectiveness in environmental remediation. BC exhibits augmented adsorption capacities, catalytic functionalities, and interactions with microorganisms, facilitating the removal of contaminants from different matrices of the environment. Recently, BC and their products such as nano‐BC have gained widespread recognition as a feasible option for sustainable carbon material. Fabrication, characterization, modification, and diverse applications of BC were also discussed in detail. Its integration into agriculture holds promise for enhancing soil organic matter, augmenting production, and mitigating gas emissions, thereby contributing to food security and climate change mitigation. In conclusion, BC and nano‐BC emerge as a promising avenue for addressing environmental challenges and advancing sustainable development objectives. However, further research is warranted to optimize synthesis methodologies, elucidate long‐term environmental implications, and facilitate scalable production for widespread adoption.
... Biochar (BC) is carbonaceous material derived from biomass feedstock, which always has porous structure, abundant functional groups, high cation exchange capacity (CEC), and can slowly release nutrients to improve soil fertility (Luo et al. 2013;Heitkotter and Marschner 2015;Yuan et al. 2021a). Many studies revealed that BC decreased soil HMs bioavailability by immobilization via surface complexation, electrostatic attraction, pore-filling, cation exchange and/or cation-π electron donor-acceptor interaction (Park et al. 2011;Li et al. 2017aLi et al. , 2018Chen et al. 2021;Yang et al. 2021). ...
Article
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Background and aims Converting distillers’ grains (DGs) into biochar (BC) is sustainable option for waste-recycling, but how different aging times and application rates DG-derived BC (DG-BC) influenced lettuce growth and cadmium (Cd) uptake in soil was unclear. This study explored DG-BC rate- and aging time-dependent effect on lettuce growth and Cd uptake, and effect mechanisms from insights of soil nutrient and Cd bioavailability, lettuce metabolic activity and rhizospheric bacterial composition. Methods Pot experiments involved three DG-BC rates (1%, 2%, 4%) and three aging times (0, 3, 6 months) in Cd-polluted soil. Effects of different DG-BC rates and different aging times on lettuce growth, metabolic activity and Cd uptake, soil nutrient and Cd bioavailability, and rhizospheric bacterial composition were explored. Results Rising DG-BC rate and aging time increasingly enhanced lettuce growth, antioxidant activities and soil nutrient availability, while progressively decreased Cd bioavailability and Cd uptake by lettuce. Sphingomonas, RB41 and Nitrospira abundance in rhizosphere soil could be enhanced at higher DG-BC rate, and DG-BC aging in soil further promoted or maintained their enhanced abundance at higher DG-BC rate. Thus, the enhanced abundance of these keystone genera played crucial roles in promoting lettuce growth, soil nutrient availability, and decreasing Cd bioavailability and uptake. Conclusions Applying 4% DG-BC with 6 month-aging maximized lettuce growth and minimized Cd uptake by maximally decreasing Cd bioavailability, increasing soil nutrient availability and regulating rhizospheric bacterial composition, thus becoming a suitable DG-BC application strategy to promote lettuce production and mitigate Cd-induced health risk through lettuce consumption.
... In a study of Bera et al. (2016), the soil FDA activity in the topsoil was greater by 63% in the NPK + biochar treatment compared to that in NPK treatment. The vast surface area of biochar provides a home for microbial colonization (Luo et al. 2013); and its presence affects soil microbial activities and biomass (Lehmann and Joseph 2009). These findings may be related to the combined effect of labile C and mineral N in the biochar that served as stimulus in enhancing the microbial activities (Chen et al. 2015). ...
Article
With the growing research interest in utilizing nutrient-enriched biochar as alternative slow-release fertilizer, a study was conducted to examine the alterations in soil chemical properties and microbial activity following the use of fertilizer enriched corn cob biochar (FEB) in clay loam soil (Typic Eutrudepts) at ASI-CAFS, U.P. Los Baños in November 2020. The agronomic and physiological responses of corn grown in soil with treatments: no fertilizer (T1), corn cob biochar alone (T2), recommended rate of chemical fertilizer (T3), and FEB at the rate of 5.0 (T4), 7.5 (T5) and 10.0 (T6) tons ha-1 were evaluated. The application of FEB improved the chemical soil properties and soil microbial activity due to the presence of higher levels of soil organic carbon and essential macronutrients. The corn plants applied with the FEB had the highest leaf chlorophyll content. The FEB with the lowest rate (5 tons ha-1) significantly increased corn plant biomass and fruit yield. Moreover, FEB application significantly enhanced the N, P and K concentration on corn stalk and fruit. Significant positive correlations were obtained between the total N, available P and exchangeable K in soil and the total N, P and K concentration in plants. These findings provide a novel opportunity for the use of FEB as an efficient soil ameliorant.
... Several studies also reported high microbial nutrient concentration in nutrient-depleted systems such as more microbial P in P-limited ecosystems (Elser and Hamilton, 2007;Xu et al. 2011) and high microbial N and P in the boreal forest, a highly N-limited (DeLuca et al. 2008) and slightly P limiting system (Giesler et al. 2002). The limitation of nutrients in soils may shift the decomposition ability of microbes to acquire N or P and induce high decomposition activity (Luo et al. 2013;Chen et al. 2014). ...
Article
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The change in soil microbial biomass and stoichiometry in different land uses of Northeast India were assessed by using the fumigation extraction method. The pattern of microbial biomass C, N, and P followed the sequence of forest (650.36, 62.86 and 254.54μgg − 1) > grassland (62.86, 39.30 and 31.76 μgg − 1 > cropland (31.84,18.62 and 15.54 μgg − 1), and exhibits seasonality with the lowest concentrations during the winter season across all land uses. The maximum concentrations were recorded during the rainy season in the forest and the summer season in both grassland and cropland. Microbial ratios (C: N, C: P and N: P) and proportions of microbial biomass to total soil nutrients vary with a variance in land use types. Soil microbial biomass exhibited a positive significant relation with soil nutrients but negatively related with soil temperature and moisture in all the study sites. Two-way ANOVA of soil microbial biomass exhibits significant differences due to seasons and land use types (p< 0.01). The microbial stoichiometry of the present study indicates N limitations in the study sites, while the proportion of microbial nutrients to total soil nutrients reveals nutrient mineralization in the forest and immobilization and competition in grassland and cropland. Furthermore, this study indicates that landuse and soil management practices interfere with microbial stoichiometry and nutrient release and immobilization patterns. Improving the retention of organic matter in ecosystems may enhance microbial activity and soil health.
... Microorganisms utilize biochar particles for colonization, growth, and reproduction. Luo et al. (2013) observed dense microbial colonization on porous biochar structure made from lignocellulose mass obtained from Miscanthus giganteus. A huge diversity of microorganisms was grown in manure-based biochar-applied soil and Actinobacteria with spores and hyphae were dominant (Dai et al., 2017a,b). ...
... They discovered that acetoneextracted carbon had a significant impact on microbial biomass, community structure, and the nitrogen cycling mechanism (Dai et al., 2018a(Dai et al., , 2019. Moreover, it was discovered that the labile carbon in biochar was connected to both community succession and microbial respiration in soil (Luo et al., 2013;Watzinger et al., 2014). ...
Chapter
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The chapter explores the interrelationship between biochar and soil microorganisms, focusing on the role of biochar as a growth promoter and its effects on soil contaminants. Biochar and microorganism interactions are intricate and multifaceted. Biochar–microbe interactions, the dissipation and transformation of contaminants, and the immobilization of contaminants are discussed. Various interactions between biochar and soil microorganisms are also investigated. Overall, this review highlights the potential of biochar to promote soil microbial activity and mitigate the impacts of contaminants, while emphasizing the need for further research in this field.