Stalk Biochar Research Articles

Effect of Mulberry Stalk Biochar, FYM and Humic Acid on Growth, Yield and Quality of Mulberry (Morus alba L.)

A field experiment was conducted in a mulberry crop to investigate the impact of soil application of mulberry stalk biochar with FYM and foliar spray of humic acid on the growth, yield and quality of mulberry at a farmer's field in Mylandlahalli Village, Chintamani Taluk, Chikkaballapura District. The experiment was set up in a randomized complete block design with eight treatments, each replicated thrice. Result of the experiment revealed that among the various treatments applied, the combined application of biochar with FYM and humic acid (T8: Soil application of biochar @ 10 t ha-1 + FYM @10 t ha-1 + 2% Humic acid foliar spray) had significant effect on plant height (196.10 cm), number of shoots per plant (15.06), number of leaves per shoot (31.78), leaf yield (26.22 t ha-1), crude protein (20.28%) and lower crude fibre (1.56%). The next best treatments were T7 (Soil application of biochar @ 7.5 t ha-1 + FYM @10 t ha-1 + 1% foliar spray of humic acid) and T6 (Soil application of biochar @ 5 t ha-1 + FYM @10 t ha-1 + 0.5% Humic acid foliar spray) and these treatments were statistically comparable but significantly superior to the package of practice (POP).

The Influence of Pyrolysis Temperature on the Performance of Cotton Stalk Biochar for Hexavalent Chromium Removal from Wastewater

The Influence of Pyrolysis Temperature on the Performance of Cotton Stalk Biochar for Hexavalent Chromium Removal from Wastewater

Ultrasound assisted removal of methylene blue using functionalized mesoporous biochar composites

Global wastewater pollution issues demands developing innovative and cost-efficient techniques for wastewater treatment. The current study reports application of different metal oxide (iron, copper, zinc) doped carbon-based materials such as activated carbon (AC), groundnut shell (GS), cotton stalk (CS) and biochar (BC) for the removal of methylene blue (MB). Iron oxide-doped AC exhibited significantly higher adsorption capacity (∼32 mg/g) with all the other metal oxide-doped AC having the adsorption capacity below ∼10 mg/g. Adsorption of MB on FeCS followed the Freundlich isotherm, suggesting multilayer adsorption on the heterogeneous active sites. Kinetic models indicated dominant chemisorption mechanisms, aligning well with the pseudo-second-order model. Higher adsorption capacity under alkaline pH conditions is attributed to the prevalence of negative charges on the surface. The presence of ultrasound further intensified the adsorption behavior resulting in a maximum removal efficiency of ∼90 % within 10 min. An optimum adsorbent loading of 0.5 g/L was determined for effective removal of MB. FeCS adsorbent displayed stable performance over multiple cycles, affirming its reliability for reuse. These results shed light on the practical application of biochars derived from large scale pyrolysis process for the wastewater remediation.

Biochar from Manihot esculenta stalk as potential adsorbent for removal of reactive yellow dye

Textile effluent treatment is crucial for a cleaner and safer community. The purpose of this study is to utilize biochar prepared from Manihot esculenta stalk to remove reactive yellow dye through Pyrolysis at 350 °C for 210 min. The effect of quantity of adsorbent, pH values of the adsorbate solution experimented, contact time required, starting dye concentration, current temperature of the solution, speed of agitation, as well as size of the particle on reactive yellow dye removal was examined using biochar through batch trials. At an equilibrium period of 25 min, pH of 7, bio-char dosage of 2 g, temperature of 25 °C, agitation speed of 150 rpm, as well as particle size of 231 µm, 86% of the dye could be removed with highest adsorption capacity of 53.47 mg/g. Pseudo-first order type kinetics in addition to the Langmuir isotherm model were set up to finest fit the adsorption model of reactive yellow dye onto biochar from M. esculenta stalk. The process is chemisorption, exothermic, feasible, and spontaneous, as it is predicted by the thermodynamically negative enthalpy as well as entropy of adsorption values. The spent M. esculenta stalk biochar was reused for six cycles of adsorption at same optimal process conditions and adsorption capacity was found to be insignificant up to fourth cycle. Also, M. esculenta biochar was characterized through scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDAX) and Fourier Transform Infrared Spectroscopy (FTIR) for morphology, elemental composition, and functional groups respectively. So, the M. esculenta stalk biochar could be an active adsorbent for elimination of reactive dye from the solution of dye.

Inactivation of harmful cyanobacteria Microcystis aeruginosa by Cu2+ doped corn stalk biochar treated with different pyrolysis temperatures

In this study, biochars (BCs) derived from corn stalk treated at various pyrolysis temperatures (350–950 °C) were prepared and then loaded with Cu2+ to form highly efficient algaecide, i.e. Cu2+-doped BC composites (Cu-BCs). The results showed BCs pyrolyzed at higher temperatures suppressed the growth of Microcystis aeruginosa in the order of BC550 ≫ BC750 > BC950, while BC350 accelerated cell growth due to the release of inorganic nutrients. The difference could be attributed to the physicochemical characteristics, including specific surface area, adsorption capacity of nutrients and the presence of particularly persistent free radicals. Furthermore, Cu-BCs exhibited the improved inactivation performance, but the 72 h growth inhibition rates and reaction activities of Cu-BCs were still influenced by the Cu2+ loading ratio and pyrolysis temperature. These results, reported for the first time, demonstrated the algae inactivation efficiency of pristine BCs, and Cu-BCs were principally manipulated by the biochar pyrolysis temperature.

Relationships between different types of biochar and N2O emissions during composting based on roles of nosZ-carrying denitrifying bacterial communities enriched on compost and biochar particles

Biochar has demonstrated the potential in mitigating N2O emissions during composting. However, little is known about how microbial communities on biochar particles interact with N2O emissions. This study selected three types of biochar (corn stalk biochar (CSB), rape straw biochar (RSB), and bamboo charcoal (BC)) to investigate the relationship between N2O emissions and denitrifying bacterial communities on compost and biochar particles. The results showed that N2O emissions rate were higher in the thermophilic phase, and the average emissions rate of BC treatment were lower 40% and 26% than CSB and RSB, respectively. The nosZ-carrying denitrifying bacterial community played a key role in reducing N2O emissions, and the network indicated that Rhizobium and Paracoccus on compost particles may have played major roles in reducing N2O emissions, but only Paracoccus on biochar particles. Notably, BC enhanced the efficiency of N2O emission reduction by enhancing the abundance of these key genera.

Effectiveness of corn stalk biochar in amending the contaminated soil attributes and enhancing the sustainable grass growth

Effectiveness of corn stalk biochar in amending the contaminated soil attributes and enhancing the sustainable grass growth

Inhibiting release of phenanthrene from rice-crab coculture sediments to overlying water with rice stalk biochar: Performance and mechanisms

Rice crab coculture is a new ecological agriculture model combining rice cultivation and crab farming. Current research related to rice crab coculture only focuses on production theory and technical system establishment, while ignoring the potential ecological risk of Polycyclic aromatic hydrocarbon(PAHs) in rice crab coculture sediment. In this study, rice straw was used to make rice straw biochar to explore the performance and mechanism of inhibiting release of phenanthrene(PHE) from rice-crab coculture sediments to overlying water with rice stalk biochar. The kinetic and isotherm adsorption data were best represented by the Langmuir model and pseudo-second-order model with a maximum adsorption capacity of 53.35 mg/g at 12 h contact time. The results showed that PHE was released from the rice-crab substrate to the overlying water in dissolved and particle forms as a result of bioturbation, and the PHE concentrations in dissolved and particle forms were 20.9 μg/L and 14.22 μg/L, respectively. This leads to secondary ecological risks in rice-crab co-culture systems. This is related to dissolved organic carbon(DOC) carrying the dissolved PHE and total suspended solids(TSS) carrying the particle PHE in the overlying water. Due to its large specific surface area, rice straw biochar is rich in functional groups, providing multiple hydrophobic adsorption sites. After adding rice straw biochar at 0.5 % w/w (dry weight) dose, the removal efficiency of dissolved and particulate PHE in the overlying water were 78.99 % and 42.11 %, respectively. Rice straw biochar is more competitively adsorbed PHE in the overlying water than TSS and DOC. The removal efficiency of PHE from the sediment was 52.75 %. This study confirmed that rice stalk biochar could effectively inhibit PHE migration and release in paddy sediment. It provides an environment- friendly in situ remediation method for the management of PAHs pollution from crab crops in rice fields.

Characterization and kinetics of iron oxide reduction by corn straw biochar prepared by pyrolysis using superheated steam atmosphere and hydrothermal processes

Current research on using biochar as foaming agents in electric arc furnace (EAF) steelmaking is limited to pyrolysis biochar treated with nitrogen. Therefore, this study used pyrolysis corn stalk biochar treated with nitrogen (PN) as a reference, the physical and chemical properties, the ability to reduce iron oxide, and the reaction mechanism of pyrolysis corn stalk biochar treated with superheated steam (PSS) and hydrothermal corn stalk biochar (HC) were investigated. HC contains a large number of hydrogen-containing functional groups, which can release large amounts of H2 during the reduction of iron oxide, while PSS has a higher fixed carbon content and produces higher amounts of CO and CO2 gas. Dividing the thermogravimetric results into three reduction stages, the results show that the large amount of volatile fraction contained in HC contributes to Stage 1 and that the gasification reaction ability of PSS is stronger than that of PN. The results of the kinetic analysis showed that the best reaction mechanism for the three reduction stages of the three biochars was the Jander diffusion equation. This work provides theoretical guidance for the use of PSS and HC as foaming agents in EAF steelmaking.

Boron seed coating combined with seed inoculation with boron tolerant bacteria (Bacillus sp. MN-54) and maize stalk biochar improved growth and productivity of maize (Zea mays L.) on saline soil

Salinity exerts significant negative impacts on growth and productivity of crop plants and numerous management practices are used to improve crop performance under saline environments. Micronutrients, plant growth promoting bacteria and biochar are known to improve crop productivity under stressful environments. Maize (Zea mays L.) is an important cereal crop and its productivity is adversely impacted by salinity. Although boron (B) application, seed inoculation with boron-tolerant bacteria (BTB) and biochar are known to improve maize growth under stressful environments, there is less information on their combined impact in enhancing maize productivity on saline soils. This study investigated the impact of B seed coating combined with seed inoculation with BTB + biochar on maize productivity under saline soil. Four B seed coating levels [0.0 (no seed coating), 1.0, 1.5, 2.0 g B kg−1 seed], and individual or combined application of 5 % (w/w) maize stalk biochar, and seed inoculation with Bacillus sp. MN-54 BTB were included in the study. Different growth and yield attributes and grain quality were significantly improved by seed coating with 1.5 B kg−1 seed coupled with biochar + BTB. Seed coating with 1.5 B kg−1 seed combined with biochar + BTB improved stomatal conductance by 32 %, photosynthetic rate by 15 %, and transpiration ratio by 52 % compared to seed coating (0 B kg−1 seed) combined with biochar only. Similarly, the highest plant height (189 cm), number of grain rows cob−1 (15.5), grain yield (54.9 g plant−1), biological yield (95.5 g plant−1), and harvest index (57.6 %) were noted for B seed coating (1.5 g B kg−1 seed) combined with biochar + BTB inoculation. The same treatment resulted in the highest grain protein and B contents. It is concluded that B seed coating at 1.5 g B kg−1 seed combined with biochar + BTB inoculation could significantly improve yield and quality of maize crop on saline soils. However, further field experiments investigating the underlying mechanisms are needed to reach concrete conclusions and large-scale recommendations.

Experimental Study on Properties of Syngas, Tar, and Biochar Derived from Different Gasification Methods

Biomass gasification technology is a clean and renewable energy utilization approach. Understanding the evolution of gasification product properties is crucial to achieving carbon neutrality goals. A fixed-bed reactor is employed for the biomass gasification with CO2 in this study. Various methodologies have been conducted to characterize the syngas, tar, and biochar produced from the electric gasification (EG) and microwave gasification (MG) of oak and corn stalk samples at different temperatures. When gasifying the same biomass at the same temperature, the syngas yield of MG is generally 3–7% higher than that of EG, and the difference increases with decreasing temperature. The biochar yield of MG is 3–6% higher than that of EG. EG produces more tar at 600–800 °C. The yield of syngas increases as the gasification temperature rises from 600 to 1000 °C, but that of tar and biochar falls. The syngas mainly comprises H2, CH4, CO, and CO2. MG produces 8–15% higher CO content and 2.5–3.5% higher H2 content than EG. This is due to different heating mechanisms. The net calorific value of syngas increases with temperature, reaching a maximum of 11.61 MJ m−3 at 1000 °C for syngas from corn stalk MG. When the temperature rises from 600 to 1000 °C, more primary tars are converted into polycyclic aromatic hydrocarbons (PAHs). At 900 °C, corn stalk biochar from MG has a maximum specific total pore volume (0.62 cm3 g−1), surface area (525.87 m2 g−1), and average pore diameter (4.18 nm). The intensities of the characteristic peaks of biochar functional groups decrease gradually. The heating method has little effect on the types of functional groups.

Ni-supported pigeon pea stalk biochar as a catalyst for ex situ tar cracking in biomass gasification

Ni-supported pigeon pea stalk biochar as a catalyst for ex situ tar cracking in biomass gasification

Qualitative and Quantitative Investigation of Biochar-Cu0 Composite for Nickel Adsorption.

The current investigation deals with the treatment of water pollution that is caused by the leaching of nickel ions from the metallurgical industry and new-energy batteries. Therefore, an eco-friendly treatment of nickel through the use of a composite of cotton stalk biochar with nanozerovalent copper has been presented in this investigation signifying the impact of zerovalent copper in enhancing the adsorption capacity of biochar for nickel adsorption. Thermogravimetric analysis data showed the adsorbent to be significantly stable in the higher thermal range, whereas transmission electron microscopy analysis confirmed the particles to be 27 nm and also showed the cubic geometry of the particles. A much closer scanning electron microscopy analysis shows the morphology of particles to be cubic in shape. Batch adsorption indicated a positive influence of pH increase on adsorption due to the electrostatic attraction between positive nickel ions and post point of zero charge (pHPZC) negative surface of copper biochar composite (pH > 5.5). A high adsorption rate was observed in the first 60 min, whereas adsorption increased with the increase in temperature from 303 to 318 K. Kinetic modeling confirmed the pseudo-first-order to fit best to the data. The apparent activation energy (11.96 kJ mol-1) is indicative of the chemical nature of the process. The adsorption data fitted well to the Langmuir adsorption model. The negative values of apparent ΔG° and the positive values of apparent ΔH° indicate the spontaneity and endothermicity of the process, respectively, whereas the positive values of apparent ΔS° point toward increased randomness during the process. Postadsorption XPS suggests the adsorption of nickel on the surface of biochar composites in the form of Ni(OH)2 and NiO(OH).

Interventions to Improve Potassium Availability in Light Textured Alfisols Supporting FCV Tobacco

Aim: To investigate the effect of soil inversion in conjugation with combined application of SOP with cheaper potassium supplements like tobacco stalk biochar (TS biochar) and barn wood ash (BWA) on potassium fractions in light textured sandy loam soils supporting FCV tobacco.
 Study Design: Split plot design
 Place and Duration of Study: ICAR-CTRI RS, Jeelugumilli, Andhra Pradesh, India.
 Methodology: A field experiment was conducted with two main plots and seven sub-plots which are replicated thrice. The two main plots are consisting of soil inversion practices i.e., (i) soil inversion with MB plough (ii) without soil inversion and seven sub plot treatments viz., one without potassium, two sulphate of potash treatments at the rate of 100 % and 75 % of recommended dose of fertilizer (RDF), two TS Biochar treatments along with SOP and two BWA treatments along with SOP at the rate of 100 % and 75 % RDK each. Soil Samples were collected at 60 DAP to study various potassium fractions in the soil.
 Results: Results indicated that mean water-soluble potassium has been increased from 17.90 mg kg-1 in without soil inversion to 27.61 mg kg-1 in with soil inversion respectively and among the potassium input management practices highest mean water-soluble potassium of 26.60 mg kg-1 was observed in S4 [100% K through SOP + Tobacco Stalk Biochar (1:1)] treated plots which is on par with S2 [100% K through SOP]. An increase in soil mean exchangeable potassium from 40.07 mg kg-1 without soil inversion to 58.79 mg kg-1 with soil inversion was observed and among the potassium input management practices the highest available potassium was observed in S4 [100% K through SOP + Tobacco Stalk Biochar (1:1)] treated plots with a mean value of 60.14 mg kg-1 which was on par with S6 [100% K through SOP + Barn wood ash (1:1)].
 Conclusion: Both soil inversion and potassium input management has improved the water soluble, exhangeable K in soil while no much influence on non-exchangeable and total K were observed.

Adsorption of total petroleum hydrocarbon in groundwater by KOH-activated biochar loaded double surfactant-modified nZVI

Introduction: Crude oil and petroleum hydrocarbon contamination is commonly found in the soil and groundwater during the various processes of mining, processing, and utilization due to issues such as inefficient environmental management, random wastewater discharge, and storage tank leakage.To address this issue, we will use corn stalk biochar (SBC) and surfactants to improve the stability and chemical reactivity of nZVI, thereby enhancing its ability to remove pollutants, and explore the adsorption effect and mechanism of composite materials for petroleum hydrocarbons.Methods: Modified corn stalk biochar (SBC) was synthesized through high-temperature carbonization and KOH activation. Subsequently, the iron/carbon composite PN-nZVI@SBC (PNMSBC) was prepared by loading nano zero-valent iron modified with dual surfactants, and it was adopted to adsorb total petroleum hydrocarbons(TPH) in groundwater. The physical and chemical properties, surface patterns, and elemental mapping of PNMSBC particles were analyzed using SEM, EDS, TEM,XRD, BET, and FTIR spectroscopy. Kinetics and isotherm tests were performed to evaluate the adsorption properties of the composites. TPH adsorption was dependent on ionic strength, initial TPH concentration, as well as pH. The adsorption mechanism combining XPS and EPR spectroscopy was explored.Results: The characterization results by SEM and TEM showed that the particle size of nZVI particles modified by surfactants became smaller, and the dispersibility was enhanced. The characterization results by XRD and FTIR confirmed the successful preparation of the composites. The BET results showed that MSBC and PNMSBC were mesoporous structures. The characterization results indicated that Polyvinylpyrrolidone (PVP) and Sodium oleate (NaOA) inhibited the oxidation of nZVI while effectively improving its reactivity. The result of the experiments on adsorption showed that the removal of TPH by PNMSBC followed Freundlich isotherm and pseudo-second-order kinetic models, thus suggesting that the main adsorption processes comprise chemisorption and multilayer heterogeneous adsorption. The adsorption capacity of PNMSBC was increased by the abundance of macro and microporous structures. To be specific, a maximum Langmuir adsorption capacity (qm) was achieved as 75.26 g/g. The result of batch experiments indicated that PNMSBC continuously removed considerable TPH under a wide pH range from 2 to 6. The adsorption mechanism of PNMSBC includes surface adsorption, oxidation, complexation, and electrostatic interaction.Discussion: In brief, PNMSBC has a promising application for the adsorption of TPH in groundwater remediation.

Microwave disinfection strengthened by a biochar-based microwave absorbing material for sewage resource utilization

ABSTRACT Proper disinfection treatment is the basic guarantee for safe utilisation of sewage. However, the commonly used disinfection methods are not suitable for nutrients containing reclaimed water. In this work, the microwave disinfection method assisted by a microwave-absorbing material in recycled water samples was investigated. Magnetic corn stalk biochar (MCSB), the microwave absorbing material, was prepared by high temperature carbonisation of corn stalk particles impregnated with ferrous sulfate. Escherichia coli and fecal coliforms were selected as target microorganisms to investigate the disinfection efficiency of MCSB assisted microwave radiation (MW/MCSB). The addition of microwave absorbing materials significantly improves the disinfection effect of water samples. Compared with the microwave radiation (MW) without MCSB, the bactericidal rate by using 107 CFU/L E. coli suspension increased from 63.5% to 100% at 480 W for 30 s after adding 4 g/L MCSB. Besides, the effects of MCSB dosage, microwave power, microwave radiation time, and initial bacterial concentration on disinfection efficiency were explored. Moreover, the bactericidal efficiency for actual sewage samples was also demonstrated by treating the effluent from septic tank sewage. The residual fecal coliforms in treated water samples met China’s farmland irrigation water standard (GB 5084-2021). The result indicates that the proposed method of microwave disinfection strengthened by MCSB has a promising application prospect for reclaimed water disinfection.

Removal of Pb(II) from Aqueous Solution and Adsorption Kinetics of Corn Stalk Biochar

In this work, the Pb adsorption and removal ability of biochar from simulated Pb(II)-contaminated wastewater, adsorption isotherms, kinetics, and thermodynamics were studied. Adsorption characteristics of biochar on Pb(II) were analyzed by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscope with energy dispersive spectrometer (SEM-EDS). The influence of the pH of the solution, the contact time, and the biochar dose on the removal of Pb(II) were investigated by single-factor design and response surface analysis. With the increase in biochar dose from 2 g/L to 4 g/L in wastewater, the Pb(II) amount adsorbed on biochar reduced from 21.3 mg/g to 17.5 mg/g. A weakly acidic environment was more conducive to the ligand exchange between Pb(II) ions and biochar. Pb(II) adsorption kinetics of biochar showed that the Pseudo-first-order model was more suitable than other employed models to describe the adsorption process. During the isothermal adsorption process, Langmuir and Freundlich’s isotherms fitted the adsorption data very well (R2 > 96%). The Pb (II) adsorption onto biochar was spontaneous in the specified temperature range (298–318 K) and the process was exothermic. Simultaneously, the optimal conditions were a pH of 5, a contact time of 255 min, and a biochar dose of 3 g/L, under which the maximum predicted Pb(II) removal efficiency was 91.52%.

Influence of Modified Biochar on Soil Fluoride and Cadmium Speciation and Their Bioavailability to Tea Seedling (Camellia Sinensis L.)

ABSTRACT Biochar is widely used as a good soil amendment, while knowledge of modified biochar application in tea garden soils contaminated by fluoride (F) and cadmium (Cd) is insufficient. The tea seedling (Camellia sinensis L.) growth assay was performed to evaluate interaction of soil Cd and F and the improving effect of aluminum trichloride-modified corn stalk biochar (Al-BC) on their speciation, phytoaccumulation and phytotoxicity. Results showed that soil F speciation ratio sequence was as follows: residual > exchangeable > organic-bound > water-soluble > Fe/Mn oxide-bound. Soil exchangeable Cd was the largest Cd speciation (>35.6%), probably due to the low pH values in the acid tea gardens. Root F contents showed a strong significant relationship with soluble F contents (r = 0.92, P < .01) and similarly root Cd highly connected with exchangeable Cd (r = 0.86, P < .01). Seedling height, fresh and dry weight, root surface area, length, and photosynthetic pigment showed different sensitivities to F or Cd oxidative stress and toxicity effects, and only root F contents significantly inversely correlated with them (r = 0.74–0.80, P < .01). The interaction of Cd and F, could influence their speciation distribution and antagonized each other in root accumulation. Meanwhile, joint simulation models showed that antagonistic effects were observed in the F and Cd mixture soils for most cases at Enshi. Biochar application reduced bioavailable F and Cd contents, and thus decreased F and Cd accumulation in tea roots and obviously alleviated toxicity effects. For instance, biochar application significantly reduced root F contents, which had 33.2% to 62.2% declines at Enshi and 39.7% to 77.2% declines at Huanggang. Meanwhile, the soil properties were improved as biochar added, with an increase in soil pH, EC, CEC and organic matter. Overall, Al-modified biochar was beneficial environmental materials for reducing both F and Cd bioavailability.

Biochar alleviated the toxic effects of PVC microplastic in a soil-plant system by upregulating soil enzyme activities and microbial abundance

Plastics have become an emerging pollutant threatening the sustainability of agroecosystems and global food security. Biochar, a pro-ecosystem/negative carbon emission technology can be exploited as a circular approach for the conservation of plastics contaminated agricultural soils. However, relatively few studies have focused on the effects of biochar on plant growth and soil biochemical properties in a microplastic contaminated soil. This study investigated the effects of a cotton stalk (Gossypium hirsutum L.) biochar on plant growth, soil microbes, and enzyme activity in PVC microplastic (PVC-MPs) contaminated soil. Biochar amendment increased shoot dry matter production in PVC-MPs contaminated soil. However, PVC-MPs alone significantly reduced the soil urease and dehydrogenase activity, soil organic and microbial biomass carbon, bacterial/fungal community percentage, and their abundance (16S rRNA and 18S rRNA genes, respectively). Interestingly, biochar amendment with PVC-MPs significantly alleviated the hazardous effects. Principal component and redundancy analysis of the soil properties, bacterial 16S rRNA genes, and fungal ITS in the biochar-amended PVC-MPs treatments revealed that the observed traits formed an obvious cluster compared to non-biochar treatments. To sum up, this study indicated that PVC-MPs contamination was not benign, while biochar shielded the hazardous effects and sustained soil microbial functionality.

Amendment of different biochars changed pore characteristics and permeability of Ultisol macroaggregates identified by X-ray computed tomography (CT)

The addition of biochars produced by different feedstocks to soil affects soil aggregation, which has been shown to be critical for soil carbon sequestration, water holding capacity and plant growth. In this study, rice stalk biochar (RB) and canola stalk biochar (CB) produced at 350℃ were added to a Ultisol at the 1% rate. After a three-year incubation, the macroaggregates (5–6 mm) in soils were separated for quantification of pore structure using industrial X-ray computed tomography (CT) scanning. The RB and CB treatments significantly increased the total porosity and the ratio of connectivity to isolated porosity(C/I) in macroaggregates relative to CK treatments. The addition of biochars decreased the proportion of equant pores in the macroaggregates, while increased the proportion of irregular pores such as prolate and acircular pores, resulting in the high porosity heterogeneity in macroaggregates. The canola stalk biochar had a larger effect on the improvement of pore structure than rice stalk biochar, while having the opposite effect on pore throat structure. There was a positive correlation between porosity, connectivity and SOC in macroaggregates. Simulation results on water flow showed that the permeability for RB and CB treatments were 25.16 μm2 and 28.62 μm2, respectively, which were 116.7% and 146.5% higher than that of CK treatment (11.61 μm2). The results indicated that the biochars altered the pore structure of macroaggregates, potentially enhancing the functional services of macroaggregates such as SOC storage and hydraulic properties. The findings provided the detailed information on the effect of different biochar additions on pore structure in macroaggregates and simulated soil water movement within the macroaggregates, which is important for understanding the mechanism of biochars affecting soil aggregation and its functions.