Effects Of Biochar Application Research Articles

A review on biochar’s effect on soil properties and crop growth

Intensive cultivation of agricultural soils causes soil degradation which emphasizes the need for sustainable soil management. Biochar, a pyrolysed carbon rich material has gained great interests among the researchers because of its eco-friendly benefits in addition to soil quality enhancement. Reviews on biochar, mainly confined to its environmental benefits like carbon sequestration and climate change. In this review, we summarize i) the effect of biochar application on soil properties (physical, chemical, biological), ii) remediation potential of biochar in heavy metal contaminated soils and iii) its impact on crop productivity. The properties of biochar like pH, greater surface area, cation exchange capacity, and nutrient content positively influences the soil properties and ultimately improves the soil fertility. Their effectiveness depends on biochar type, its dosage, soil type, etc. General trends from this review indicated that biochar as an effective amendment in acid soils than the alkaline or calcareous soils. Furthermore, the biochar effects are studied mostly under controlled conditions in laboratory, which needs to be validated under field conditions having varied soil types and agro-climatic zones.

Effects of Biochar Application on Soil Bacterial Community Diversity and Winter Wheat Growth in Wheat Fields

A long-term field experiment was conducted to study the diversity of soil bacterial communities and the response of crop growth to biochar application, in order to provide a scientific basis for the rational application of biochar in agricultural fields. Four treatments were applied at 0 (B0 blank), 5 (B1), 10 (B2), and 20 t·hm-2(B3) to investigate the effects of biochar on soil physical and chemical properties, soil bacterial community diversity, and growth of winter wheat using Illumina MiSeq high-throughput sequencing technology. The results showed that soil water content, pH value, soil organic carbon, total nitrogen, nitrate nitrogen content, winter wheat biomass, nitrogen uptake, and yield showed an increasing trend with the increase in biochar amount. The high-throughput sequencing results showed that the B2 treatment significantly reduced the alpha diversity of the bacterial community at the flowering stage. The overall response of soil bacterial community composition to different application rates of biochar and phenological phases was taxonomically consistent. In this study, Proteobacteria, Acidobacteria, Planctomycetes, Gemmatimonadetes, and Actinobacteria were the dominant bacterial phyla. The relative abundance of Acidobacteria decreased, but the relative abundance of Proteobacteria and Planctomycetes increased with biochar application. The results of redundancy analysis, co-occurrence network analysis, and PLS-PM analysis indicated that bacterial community compositions were closely associated with soil parameters such as soil nitrate and total nitrogen. The average connectivity between 16S OTUs was higher under the B2 and B3 treatments (16.966 and 14.600) than under the B0 treatment. The variation in soil bacterial community (89.1%) was regulated by biochar and sampling period and partly explained the changes in the growth dynamics of winter wheat (0.077). In conclusion, biochar application could regulate the changes in the soil bacterial community and promote crop growth after seven years of application. It is suggested that 10-20 t·hm-2 biochar should be applied in semi-arid agricultural areas to achieve sustainable agricultural development.

Thallium release from biochar-amended soil to runoff in laboratory experiments

Biochar has been widely used for trace metal(loid) (TM) immobilisation in contaminated soils. However, studies on the physicochemical mobility of TMs related to biochar application are highly limited, hampering the evaluation of the immobilisation efficiency of biochar. Therefore, after confirming the ability of biochar to decrease soil Tl bioavailability, this study examined the release of Tl in dissolved and particulate forms in surface runoff and leachate from soil mixed with biochar at different dosages and grain sizes under artificially simulated rainfall and irrigation experiments. The rainfall experimental results showed that the dissolved Tl in the surface runoff decreased from 1.30 μg in the control group to 0.75 μg and 0.54 μg in the groups with 3% and 5% biochar application, respectively. With the same dosages (5%), the finer the biochar applied, the higher the immobilisation ability achieved in surface runoff and the lower the Tl amounts in the leachate, indicating that the grain size of biochar can impact Tl mobility in dissolved forms. Comparisons between rainfall and irrigation experiments indicated that raindrops disturb the soil-water surface and enhance Tl diffusion. The mass in particulate form accounted for more than 95% of lateral released Tl in surface runoff. However, biochar application did not decrease the enrichment ratio of Tl in the eroded sediments. Notably, the finest biochar group produced less mass of eroded Tl owing to the low flux of soil erosion, indicating that grain size would indirectly impact sediment-bound Tl lateral mobility. Colloidal particles should be highlighted as they carried a maximum TI of up to 38% in the rainfall leachate. Focusing on the effect of biochar application on Tl chemical- and physical mobility from the soil matrix to runoff, this study contributes the comprehensive understanding of the role of biochar in TM remediation.

Microbial reduction and alteration of Fe(III)-containing smectites in the presence of biochar-derived dissolved organic matter

Clay minerals are important components of solid-phase iron pools in soils, and the redox state of structurally-coordinated iron in clay minerals can significantly influence soil physicochemical properties. Due to increasing use of biochar in agriculture, the dissolved organic matter derived from biochar (BDOM) has become an unignorable fraction of dissolved organic carbon in soil systems. However, our knowledge regarding the effect of BDOM on soil biogeochemical processes (particularly on iron redox cycling) is still very limited. To examine the role of BDOM in the microbial reduction of Fe(III) in clays, BDOM was extracted from wheat straw biochar and selectively added to laboratory reactors in which lactate, Fe(III)-containing smectite (montmorillonite SWy-2 or nontronite NAu-2), and a typical iron-reducing bacterium Shewanella oneidensis strain MR-1 were used as the respective electron donor, electron acceptor, and reaction mediator. The results demonstrated that BDOM contained bio-reactive quinone moieties. BDOM amendment increased the initial rate and final extent of Fe(III) bioreduction by strain MR-1. Such promotion effect of BDOM might be ascribed to its quinone moieties functioning as electron shuttles between MR-1 cells and structural Fe(III) in smectite. Structural changes were observed in the bioreduced smectite systems, especially for NAu-2 reactors in which obvious dissolution and illitization occurred. These observations suggest that BDOM is bio-reactive and is able to stimulate the microbial reduction of Fe(III) in clay minerals, and may offer new insights into the effects of biochar application in elemental cycles in soils.

Effect of Biochar Application and Foliar Application of Gibberellin and Cytokinin on Growth and Flowering of Chinese Carnations Dianthus chinensis

The experiment was carried out in the Horticulture Department and Landscaping, College of Agriculture, Tikrit University, during the Agricultural season 2021-2022 to study the response of Chinese carnation to biochar and growth regular carried out with two factors Add biochar at two levels without adding and adding 10 g under the seedlings, the second factor was spraying with gibberellin and cytokinin growth regulators at four levels (no spray, spraying-1 with gibberellin at a concentration of 100 mg L-1 Cytokine spray at a concentration of 100 mg. Liter-1 and spraying with a mixture of gibberellin and cytokine). The experiment was in a randomized complete block design RCBD, and three replicates, results show that superiority of the treatment of adding charcoal and it gave the highest plant height of 77.26 cm and the highest branches numbers and dry weight 25.24 branches plant-1 and 76.15 g, Spraying with a mixture of gibberellins and cytokinin superior in the rest studied traits which were dry weight 16.02 g and NPK 1.60%, 0.26% and 1.75%, and flowers numbers 49.38 plant flowers-1, and flower diameter 3.36 cm.

Research Progress on Effects of Biochar on Soil Environment and Crop Nutrient Absorption and Utilization

As a by-product generated from the pyrolysis of biomass, biochar is extraordinary for improving the soil environment of agricultural fields, improving soil fertility, and promoting nutrient uptake and the utilization of crops. In recent years, breakthroughs in progress have been made regarding the fertility value of biochar and in investigations into the physicochemical properties of soil and into plant nutrient utilization. This review focuses on the physicochemical and biological properties of soil, on soil pollution remediation, on greenhouse gas emissions, and on the effects of biochar on the uptake and utilization of soil nutrients and plant nutrients, as well as on the preparation of biochar, and on biochar produced under different conditions. The results of the relevant studies show that the main characteristics of biochar depend on the biochemical properties and pyrolysis temperature of raw materials, which play an important role in nutrient transport and transformation in the soil. At low temperatures (≤400 ℃), the biochar prepared from manure and waste contains a large amount of nitrogen, which can be used as a nutrient source for plants. In addition, biochar enhances soil fertilizer retention by reducing soil nutrient loss, which in turn promotes nutrient uptake and utilization by crops. By controlling pyrolysis temperature and by optimizing biochar input, one can effectively reduce soil respiration, as well as reduce carbon emissions to achieve the goal of controlling carbon sources and increasing carbon sinks. Therefore, a long-term series of mapping studies on the effects of biochar application on agricultural ecosystems should be conducted, which in turn, it is hoped, will provide a theoretical reference for the physiological and ecological effects of biochar croplands.

Effect of Biochar Application on Soil Fertility, Nitrogen Use Efficiency and Balance in Coastal Salt-Affected Soil under Barley–Maize Rotation

Coastal lands are often affected by salinization, which leads to a deterioration of soil structure and a decrease in land productivity. As a widely used soil amendment, biochar has been proven to improve poor soil properties and promote crop growth and N adsorption and utilization. However, the effects of biochar on soil fertility, N use efficiency (NUE) and balance in coastal salt-affected soil have rarely been reported. Therefore, we conducted a field micro-plot experiment to study the improvement effects of different biochar rates (0, 13.5, 20.25 and 27 t/ha, corresponding to CK, B1, B2 and B3 treatments, respectively) on coastal salt-affected soil. The results showed that biochar application increased soil water content (SWC) in seasons with abundant rainfall but decreased SWC in seasons with strong evaporation, and the increase or decrease in SWC was greater with the increase in biochar rates. Biochar application increased soil salinity and decreased soil pH, although high rates of biochar increased soil salinity to a lesser extent, while low rates of biochar decreased soil pH most. Biochar application was able to reduce soil bulk density, while B1and B2 treatments decreased it to a higher degree. Moreover, biochar application increased soil macro-aggregates (>0.25 mm) and organic matter, while B2 and B3 treatments increased it to a higher degree. Biochar application improved soil fertility to an extent that crop grain increased yield by 2.84~19.88% in barley season and 12.27~16.74% in maize season. Meanwhile, biochar application also increased NUE because it promoted the increase of yield. In particular, the calculation of N balance between soil and plant systems suggested that biochar application could reduce the apparent N loss during crop planting, and B1 treatment was better at reducing apparent N loss. Overall, our study indicates that biochar application has great potential to improve poor physicochemical properties and N nutrient utilization in coastal salt-affected soil. More importantly, we suggest that biochar application rates should be controlled in coastal salt-affected soil.

Effect of biochar application on rice, wheat, and corn seedlings in hydroponic culture

In recent years, biochar has attracted considerable attention for soil quality improvement and carbon sequestration due to its unique physicochemical properties. However, the mechanism by which biochar application negatively affects the growth of crop seedlings has not been fully investigated. In this study, a hydroponic experiment was conducted to evaluate the response of rice, wheat, and corn seedlings to biochar application (CK, 0 g/L; BC1, 0.5 g/L; and BC2, 1.0 g/L). Compared with the CK treatment, the BC1 and BC2 treatments decreased the fresh shoot and root weights of rice and corn seedlings (P < 0.05), but there was no significant effect on wheat seedlings (P > 0.05). For the contents of nutrient elements in seedlings, both BC1 and BC2 treatments hindered the roots from absorbing Fe and Cu and increased the uptake of Ca and Mn. Compared with the CK treatment, the translocation factor (TF) values of Ca, Mn, and Zn were significantly decreased especially in rice seedlings (35.3%-36.8%, 68.7%-76.5%, and 29.8%-22.0%, respectively) under the BC1 and BC2 treatments, while only Mn was significantly decreased in wheat and corn seedlings (P < 0.05). Transmission electron microscope (TEM) analysis of root cross-sections showed that nano-sized biochar particles (10∼23 nm) were found in the root cells under BC2 treatment conditions. Our findings reveal that a large amount of biochar application can reduce nutrient absorption and translocation, and hinder rice, wheat, and corn seedlings, particularly rice seedling, in hydroponic system.

The Effect of Biochar Amendment on Physiological and Biochemical Properties and Nutrient Content of Lettuce in Saline Water Irrigation Conditions

Salinity often increases osmotic stress, reducing plant water uptake and inhibiting the absorption of nutrients and minerals. This imbalance situation causes physiological, biochemical disorders, and nutrient deficiencies in plants. In this study, the effects of biochar application on the physiological properties, nutrient contents and antioxidant enzyme activities of lettuce were investigated under saline irrigation water conditions. For this purpose, four different biochar doses and different irrigation water salinity levels were applied to the lettuce plant. In the study, biochar application under salt stress conditions decreased the Na, Fe, Zn content and antioxidant enzyme activity of the plant. Leaf relative water content, chlorophyll content (SPAD) and some nutrients (Ca, K, Mg, P, Cu and Mn) also increased. Therefore, biochar applied under salt irrigated water conditions offers good potential to reduce the severity of plant exposure to salinity stress. In addition, the biochar amendment helped the plant uptake of nutrients.

Effect of Biochar on Soil Physiochemical Properties and Bacterial Diversity in Dry Direct-Seeded Rice Paddy Fields

The effects of biochar application on dry direct-seeded rice paddies remains unclear. Therefore, we applied biochar to dry direct-seeded rice paddy fields over 3 consecutive years to assess its effects on soil physicochemical properties and bacterial diversity (conventional fertilization [CK]; biochar + conventional fertilization [BC]). BC increased the content of 0.25–5 mm soil water-stable aggregate particles, but decreased that of &lt;0.25 mm soil water-stable aggregates. At different soil depths, BC significantly reduced sand content and increased silt content. Compared to CK, BC significantly increased the available phosphorus and potassium content of the 0–10 and 10–20 cm soil layers. There were no significant differences in pH, organic matter, total nitrogen, total phosphorus, or total potassium content between the treatments at different soil depths. Compared to CK, BC significantly increased soil neutral phosphatase and catalase activities. Furthermore, BC significantly increased bacterial richness, but had no significant effect on bacterial diversity. According to Qualcomm sequencing analysis, BC increased the relative abundance of Verrucomicrobia, Chloroflexi, Bacteroidetes, Nitrospirae, Verrucomicrobiae, Blastocatellia_Subgroup_4, and Anaerolineae in soil compared to CK. The soil bacterial genera in BC had stronger interrelationships than those in CK. According to redundancy analysis, organic matter was the main environmental factor influencing bacterial community structure. Overall, biochar could promote soil nutrient conversion in dry direct-seeded rice paddies, improve soil effective nutrient content, change the composition of soil bacterial communities, and increase soil bacterial richness. Applying biochar in dry direct-seeded rice cultivation could help realize low-carbon agriculture.

Soil Respiration and Organic Carbon Response to Biochar and Their Influencing Factors

Biochar application is an important measure to regulate SOC. However, the effects of biochar application on soil respiration and SOC fraction of the saline soil have been scarcely investigated. Therefore, in this study, we monitored the annual SOC, nutrients, temperature, water content, and respiration rate under three maize-straw-derived biochar application doses (0, 15, and 30 t∙hm−2). Biochar enriched the soil in terms of fast-acting potassium and phosphorus, alkali-hydrolyzable N, NO3−-N, and NH4+-N to varying degrees. One-time biochar application in the trial year continued to fertilizer retention in the following year. Mineral-associated organic carbon and SOC contents increased with time after biochar application, whereas the changes in particulate organic carbon content were the opposite; soil respiration rate was reduced by 7.7–14.7%, and the reduction increased with the dose as well in successive years. The soil respiration rate and soil temperature showed a significant linear correlation, but the application of a high amount of biochar reduced the correlation between the two. Considering the soil respiration rate and physicochemical properties, the best biochar application rate for saline soil is suggested to be 30 t∙hm−2. This study is of great significance for soil carbon sequestration, emission reduction in saline areas, and the realization of a “carbon peak” in the sense of farmland.

Adsorption-Desorption Behavior and Pesticide Bioavailability of Biochar in Soil

Biochar is a porous carbon-rich substance generated by anoxic pyrolysis of biomass. Biochar has a high adsorption capacity for organic contaminants in water and soil environmental media due to its large specific surface area and surface physical and chemical characteristics. The effects of biochar application on the adsorption-desorption behavior and bioavailability of pesticides in soil are illustrated in this paper; biochar can strongly adsorb pesticides in soil due to its loose and porous properties, large specific surface area and surface energy, and highly aromatic structure. Residual pesticide pollutants are reduced, as is desorption hysteresis, which reduces pesticide desorption. Furthermore, the use of biochar reduced the absorption and efficacy of pesticides in soil. At the same time, it describes the present gaps in research on the influence of biochar on pesticide migration mechanisms and its application in pesticide pollution control, and it identifies the major scientific issues that need to be addressed. Finally, the potential application of biochar in pesticide pollution management is discussed.

Effects of Biochar Application before and after Freeze-Thaw on Soil Hydrothermal and Cotton Growth under Drip Irrigation

Biochar as an organic soil conditioner has colossal application potential. Many recent studies revealed the influence of biochar on the soil during the crop growth period. However, few studies considered the effect of seasonal freeze-thaw on biochar’s improvement effect. Therefore, we conducted a field experiment to observe the impact of biochar on soil and cotton (Gossypium hirsutum L.). We used four biochar application rates (0.33%, 0.66%, 1.00%, and 1.33% of soil mass fraction) and applied biochar in the cotton field before and after seasonal freeze-thaw, respectively. The results showed that applying biochar after freeze-thaw was more effective on soil water storage and soil temperature preservation during the cotton growth period. Moreover, applying biochar with 0.66% soil mass fraction after freeze-thaw improved the cotton biomass by 5.31~36.13%, leaf area index by −10.82~32.52%, and seed cotton yield by 3.88~21.98%. Based on the principal component analysis of cotton fiber quality, we found that 0.66% biochar application after freeze-thaw improved cotton fiber most significantly. In total, applying biochar at 0.66% soil mass fraction after freeze-thaw was the most optimal application mode for improving soil hydrothermal conditions, cotton growth, and fiber quality. Our study can provide a scientific reference for applying biochar in northern Xinjiang, China.

How much is soil nitrous oxide emission reduced with biochar application? An evaluation of meta‐analyses

AbstractNitrous oxide (N2O) is the third important long‐lived greenhouse gas next to carbon dioxide and methane and croplands are considered biogeochemical hotspots of soil N2O emissions. To reduce soil N2O and other greenhouse emissions, climate‐smart agricultural practices including biochar application have been applied. Many studies have been conducted with biochar application but results from these studies are not conclusive. To address this issue, meta‐analysis, a quantitative review that synthesizes results from multiple independent studies, has been widely used. The results from different meta‐analyses also differ but are seldomly evaluated. In this study, we evaluated meta‐analyses on the effects of biochar application on soil N2O emissions. A grand mean response ratio (RR) was further proposed to estimate an overall effect and the impacts of experiment setting, properties of biochar and soil, and agricultural practices. We found 18 meta‐analysis papers were published between 2014 and 2022. Sample size (publications or experiments) varied from less than 30 to more than 1000, with a mean sample size of 275. RR was calculated in all studies except one. While four meta‐analyses did not find a significant effect of biochar application on soil N2O emissions, all others reported reductions of soil N2O emissions, but the magnitude ranged from −10.5% to −54.8%. Synthesizing all results from these meta‐analyses, we found that biochar application overall significantly reduced the soil N2O emissions by 38.8%. The impacts increased with experimental duration till one and half years and reduced after that. Biochar application rate and C:N ratio had large influence on the effects of biochar application on soil N2O emissions. This study demonstrated that while meta‐analysis provides a more comprehensive and better estimation, the inconsistence among these studies may need to be further evaluated. A grand mean RR based on meta‐analyses could be more accurate and representative than single meta‐analysis.

Effects of Rice Husk Biochar on Nitrogen Leaching from Vegetable Soils by 15N Tracing Approach

The application of biochar can affect soil properties and retention of fertilizer nitrogen, but its effects and mechanism on the retention capacity of different forms of nitrogen in soils are still uncertain. In this study, an indoor soil column leaching experiment was conducted using vegetable soil samples with 3% rice husk biochar by mass prepared at 450 °C by pyrolysis and 150 mg N/kg 15N-labeled urea. Adding biochar increased the soil pH, thus alleviating soil acidification caused by fertilizer nitrogen application. It also increased the content of soil organic carbon, total nitrogen and available phosphorus while decreasing that of NH4+-N and NOX−-N(NO3−-Nand NO2−-N) in soils. NOX−-N was the predominant form in the leachate of all treatments, accounting for 63.15–87.90% of the total N loss. Compared to the urea-alone application (the N treatment), incorporating biochar and urea (the RBN treatment) significantly reduced total N and NOX−-N loss by 19.99% and 25.95%, respectively, while showing slight effects on NH4+-N loss. The 15N results show that fertilizer N retention in soil increased by 13.67%, while inorganic 15N leaching decreased by 25.97% after the biochar addition, compared to that in the N treatment. The RBN treatment increased fertilizer N losses in other ways (e.g., organic N leaching, ammonia and NOx volatilization) by 21.72%. Effects of biochar application on other N losses need to be further investigated. Biochar application can reduce the leaching of inorganic 15N and improve fertilizer N retention in the soil. Thus, the potential risk of fertilizer N on the quality of water bodies can be reduced.

Effects of Biochar Application on Soil Hydrothermal Environment, Carbon Emissions, and Crop Yield in Wheat Fields under Ridge–Furrow Rainwater Harvesting Planting Mode

The ridge–furrow rainwater harvesting (RFRH) planting mode is widely used in arid and semi-arid areas to solve the problems of agricultural water shortage and low productivity. However, the impact of film mulching on the stability of soil carbon pools makes this planting mode vulnerable to the risk of increased soil carbon emissions and carbon pool losses. In order to clarify the relationship between soil carbon emissions and hydrothermal factors, as well as the regulatory effect of biochar application on soil carbon sequestration and reduced emissions under this planting mode, we set up a biochar application experiment. The effects of the biochar application (at 10 Mg ha−1 biochar and 20 Mg ha−1 biochar) on the soil water dynamics, soil temperature changes, CO2-C and CH4-C flux dynamics, grain yield, carbon emission efficiency, and the net ecosystem carbon budget in wheat fields under the RFRH planting mode were investigated, with no biochar application as the control. The results showed that applying biochar increased the soil water content, soil average temperature, cumulative CH4-C uptake, wheat grain yield, and carbon emission efficiency by 3.10–12.23%, 0.98–3.53%, 59.27–106.65%, 3.51–16.42%, and 18.52–61.17%, respectively; reduced the cumulative CO2-C emissions by 7.51–31.07%; and increased the net ecosystem carbon budget by 2.91 Mg C ha−1 to 6.06 Mg C ha−1. The results obtained by equation fitting showed that in wheat fields under RFRH, the CO2-C emission fluxes had negative and positive exponential relationships with the soil water content and soil temperature, respectively, while the CH4-C uptake fluxes had no significant correlation with the soil water content and had an inverse U-shaped quadratic function relationship with soil temperature. Overall, these results suggest that the application of biochar to wheat fields under RFRH can improve grain yield, farmland carbon emission efficiency, and the net ecosystem carbon budget, and change wheat fields from a carbon source to a carbon sink. These results can provide a theoretical basis and technical support for efficient, green, and sustainable production in farmland in arid and semi-arid areas.

Effects of biochar applications on tomato plant under cadmium metal stress and on soil cadmium characteristics

A greenhouse experiment was carried out in order to determine the effects of biochar on soil Cd fractions, Cd mobility and bioavailability, Cd concentration and uptake of the tomato plant, and plant stress indicators. In the factorial experiment design, Cd metals and biochar were applied to the experimental soil. After incubation of 3 months, a tomato plant was grown and experimental soil was analyzed. The bioavailable Cd content in the soil and the soluble and exchangeable amounts of Cd in the soil fractions, Cd content and Cd uptake in the plant were significantly increased by Cd applications to the soil. Cd metal applied to the soil increased the stress indicators in a tomato plant and decreased the plant biomass values significantly. Biochar applications significantly reduced the soluble and exchangeable forms of Cd and the metal mobility factor of Cd in the soil. Depending on biochar applications, biomass values of the tomato plant was increased, and Cd concentration and Cd uptake of the plant were decreased.

Tobacco straw biochar improved the growth of Chinese cherry (Prunus pseudocerasus) via altering plant physiology and shifting the rhizosphere bacterial community

Tobacco straws are byproducts during cigarette manufacturing, which have drawn attention for how to dispose them not at the cost of environment. Processing them into biochar might turn waste into wealth given their potentials for soil amelioration and crop growth promotion. However, the effects of biochar application are variable which severely limits their application. The aim of this study was to reveal the effect of tobacco straw biochar (TBC) on growth of Chinese cherry and the underlying mechanism. In present work, the response of Chinese cherry ‘Manaohong’ (Prunus pseudocerasus Lindl.), an economically valuable cultivar in Guizhou Province, to TBC was investigated using a six-month pot experiment. The TBC facilitated photosynthesis and uptake of nitrogen, phosphorus, potassium and manganese, and further promoted the plant growth. In addition, accumulation of endogenous phytohormones was affected. Higher level of indoleacetic acid, gibberellin A3, zeatin and lower level of abscisic acid were observed in TBC. In combination with high-throughput sequencing, the activation of indoleacetic acid and inactivation of abscisic acid signal transductions were detected at gene level, which further backed up the assumption that phytohormone signaling was affected by TBC addition. Moreover, according to our proposed pathway, majority genes for flavonoid biosynthesis were upregulated indicating that flavonoids were highly synthesized in roots in response to TBC, which reshaped the rhizosphere bacterial community by allowing growth-promoting bacteria to burgeon and suggested labile organic carbon fraction was the powerful factor for rhizosphere bacterial community shift. The results of our study partially explain the underlying mechanism of biochar-mediated growth promotion and provide crucial information for application of biochar on plants with high economic value.

緑化土壌を対象としたバイオ炭混合による保水効果の検証

土壌乾燥化が懸念される人工地盤上緑化等では，保水性の観点から導入する植物種が制限されるほか，適切な潅水管理が求められる。木材等を熱分解して得られるバイオ炭は土壌保水性を向上させることが報告されており，緑化土壌への導入が期待される。一方で，バイオ炭の土壌保水効果に関する研究事例は僅少であり，適切な混合条件の解明に向けた基礎的知見の確立が望まれる。本研究では，木材を原料とするバイオ炭と赤玉土の混合土壌を作成し，ポット実験により土壌保水性を評価した。その結果，バイオ炭の混合率の高い混合条件で保水量が多い傾向がみられ，その保水効果は複数回の潅水を行った場合にも同様にみられることが示された。

Biochar Production Technologies from Agricultural Waste, Its Utilization in Agriculture and Current Global Biochar Market: A Comprehensive Review

This review comprehensively describes biochar, the term which is gaining exponential attention nowadays. The technologies to convert the agriculture waste to biochar include slow pyrolysis, flash pyrolysis, and hydrothermal carbonization. Biochar production methods are based on batch processes and continuous processes. Biochar production processes and steps involved are also discussed. Different biochar reactors are also revived, including the continuous type of biochar reactor and microwave pyrolysis reactors. Kinetics of biochar, bio-oil, and syngas production is also revived briefly with kinetic equations. Uses of biochar are comprehensively revived and discussed, including advanced applications such as catalyst production, activated Carbon production, water treatment, soil amendment, etc. All biochar characterization methods are briefly described, including proximate analysis, ultimate analysis, physiochemical analysis, surface analysis, and molecular structure analysis. Factors affecting biochar production are revived in this article. Biochar yield from different crop waste s is tabulated with temperatures involved. Post-production processing methods of biochar are included in this review. The global biochar market and current status and opportunities are also revived, the data of biochar manufacturers in India are compiled. The utilization of biochar in agriculture is revived in two subcategories: the effect of biochar application on soil health and the effect of biochar application on crop yield. At last engineered or designed biochar concept is revived.