Biochar Incorporation Research Articles

Carbon Sequestration in a Changing Climate: Management Techniques and Strategic Solutions

Carbon sequestration in agriculture plays a critical role in mitigating climate change by capturing and storing atmospheric carbon dioxide (CO2) in soil and biomass. This process involves various strategies and management practices aimed at enhancing soil organic carbon (SOC) levels while maintaining or improving agricultural productivity. Key strategies include no-tillage or reduced tillage, which minimizes soil disturbance and promotes residue retention, thus slowing down decomposition and enhancing carbon storage. Crop rotation and the use of cover crops further contribute to carbon sequestration by diversifying root structures and improving soil health. Organic farming practices, such as applying farmyard manure and compost, provide essential organic matter that enriches soil quality and increases carbon retention. Additionally, the incorporation of deep-rooted plants and biochar enhances carbon storage in deeper soil layers, making them more resilient to climate variability. The integration of these practices not only sequesters carbon but also improves soil fertility, water retention, and overall ecosystem health. Effective management of carbon sequestration in agricultural systems requires a holistic approach that considers local conditions, crop diversity, and sustainable land use practices. By adopting these strategies, agriculture can become a significant carbon sink, contributing to global efforts to reduce atmospheric CO2 concentrations while ensuring food security and environmental sustainability.

Sustainable and mechanical properties of Engineered Cementitious Composites with biochar: Integrating micro- and macro-mechanical insight

Engineered Cementitious Composites (ECC) are ductile, strain-hardening cementitious composites with a tightly controlled crack opening profile. A significant concern in the development and application of ECC is its high carbon emissions associated with high cement content consumption. As an emerging green additive, biochar can significantly cut down on the carbon emission of concrete products. However, research that integrates micro- and macro-mechanical insights with biochar incorporation is limited. In this study, micro-mechanical tools indicated that a certain amount of substitution biochar could enhance the tensile properties of ECC. The study assessed various properties including compressive strength, porosity, density, tensile performance, crack pattern, sustainability and cost of ECC with different biochar proportions. The findings showed that incorporating 10 %–20 % biochar effectively increased the tensile strain capacity and decreased the crack opening width in ECC materials. This improvement can be attributed to the introduction of finer biochar particles (≤75 μm) at the fiber/matrix interfacial transition zone, which alters the fiber-bridging force by reducing the chemical and frictional bond strength between the fiber and matrix, as revealed by micro-mechanical tests and microstructural inspection. Moreover, the utilization of biochar contributes to reducing the carbon emission of ECC, enhancing sustainability while maintaining a ∼10 % minimal reduction in compressive strength. Overall, this study introduces a novel approach for reusing low-carbon biomass waste in the production of building materials, offering potential advantages in micro- and macro-mechanical performance, cost-effectiveness, and environmental sustainability.

Waste coffee biochar and bi-oil composite modified rejuvenated asphalt: Preparation, characterization, and performance evaluation

In the realm of sustainable road construction, bio-oil has emerged as a promising and eco-friendly alternative for rejuvenating aged asphalt. Nevertheless, challenges arise due to poor stability, diminished performance at elevated temperatures, and limited anti-aging properties. This study introduces an innovative approach by blending biochar, obtained from the pyrolysis of waste coffee grounds, into bio-oil to create a composite modified regenerator. Initially, the study conducts a microscopic characterization of the biochar using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). Subsequently, the rheological properties of this composite rejuvenated asphalt are evaluated across low, moderate, and high-temperature ranges using bending beam rheometer (BBR), linear amplitude sweep (LAS), and multiple stress creep and recovery (MSCR) tests. Departing from the traditional emphasis on initial property restoration, it further delves into performance alterations after re-aging of rejuvenated asphalt through temperature sweep (TS) and Fourier transform infrared spectroscopy (FTIR) tests, providing a comprehensive assessment of the anti-aging characteristics of rejuvenated asphalt. Additionally, gel permeation chromatography (GPC) is employed to quantitatively analyze the changes in asphalt molecular weight distribution. The microscopic characterization reveals the development of a rough and porous structure within the biochar, facilitating enhanced adhesion and interaction between the rejuvenator and the asphalt binder. Moreover, bio-oil rejuvenated asphalt exhibits excellent low-temperature crack resistance and moderate-temperature fatigue resistance. Following the incorporation of biochar, notable enhancements in high-temperature rutting resistance and anti-aging properties are observed, validating the efficacy of the biochar with bio-oil composite modified regenerator. To achieve optimal performance outcomes, a biochar content of 6 % (as a proportion of aged asphalt), corresponding to a 1:1 ratio of biochar to bio-oil, is recommended. Under this condition, the properties of the composite modified rejuvenated asphalt demonstrate comparability to those of the original asphalt. In summary, this research underscores the potential for integrating waste coffee biochar material into infrastructure development, thereby promoting circular economy principles and advancing more sustainable construction practices.

Exploring synergistic solid lubrication for enhanced tribological performance in biochar-reinforced aluminum matrix composites fabricated by induction sintering

This study presents a pioneering methodology for the synthesis of aluminum matrix composites (AMCs) fortified with biochar, sourced from renewable biomass feedstocks. Employing a systematic approach, various biochar weight percentages were meticulously investigated to discern their impact on the mechanical and tribological properties of the resulting composites. Through a comprehensive battery of tests, encompassing evaluations of compressive strength and hardness, the study elucidated significant enhancements in mechanical robustness consequent to biochar integration. Notably, the mixture formulation with 7.5 wt. % biochar emerged as the optimal configuration, showcasing an impressive 8.83% augmentation in compressive strength and a notable 15% elevation in the hardness relative to the pristine aluminum pure matrix. The research extends beyond traditional analyses, introducing an exploration of tribological performance. The incorporation of biochar is anticipated to impart solid lubricating properties, influencing wear and friction characteristics. Future research directions may delve into the nuanced interplay between biochar content and tribological enhancements, offering insights into the tailored manipulation of mechanical and tribological properties in AMC through biochar reinforcement. The examination of wear and friction exhibited that the friction coefficient decreased by 6.4% when 10 wt. % of biochar was added. Furthermore, the wear resistance improved proportionally with the biochar weight percentage, regardless of the normal loads applied. The finite element model further demonstrated an enhancement in load-carrying capacity due to biochar incorporation. Finally, analysis of the texture of the rubbed surface presented that the inclusion of biochar in an AL matrix changed the way wear occurs and decreased the amount of weight lost during friction. The resulting materials not only exhibit improved mechanical strength but also hold promise for applications in industries that demand robust, environmentally conscious solutions with enhanced tribological performance.

Fe(III) reduction mediates vanadium release and reduction in vanadium contaminated paddy soil under different organic amendments

Vanadium(V) contaminated soil is abundant in iron(Fe) oxides due to co-occurrence of V and Fe bearing minerals. However, biogeochemical transformation of redox-active V and Fe in soil, and the bacteria involved, has remained less investigated. This study explored the extent to which microbial mediated organic decomposition coupled to Fe(III) reduction contributed to V(V) release/reduction in V-contaminated paddy soil under different organic amendments. Soil flooding decreased toxic reducible V while increased less toxic oxidizable V. Glucose and straw promoted V(V) release with temporarily increasing V(V) concentration by 73.59–106.34 mg/kg compared to the control treatment and subsequently promoted V(V) reduction with decreasing V(V) to concentrations eventually similar to the control treatment. Biochar incorporation under glucose and straw amendments moderately alleviated V(V) release. The significantly positive correlation between Fe(II) and V(V) concentrations during the V solubilization process indicated a temporal coupling of Fe(III) reduction and V(V) release. Clostridium, and Massilia mediated Fe(III) reductive dissolution and V(V) release, while Anaeromyxobacter, Sphingomonas, Bryobacter, Acidobacteriaceae and Anaerolineaceae contributed to V(V) reduction. This study provides a deeper understanding of V biotransformation coupled to Fe and C cycling and suggests a remediation strategy for V-contaminated soils via regulating Fe(III) reduction to weaken V(V) release or to promote V(V) reduction.

Evaluating CO2 sequestration through Technosol constructed from coal mining waste

This paper proposes enhancing CO2 sequestration and recovering degraded areas using Technosols constructed with coal waste and strategic materials. The evaluation of carbon capture considered four methods: (i) plant dry mass produced by Megathyrsus Maximus cv. Mombasa (ii) carbon incorporation via biochar, (iii) microbial biomass carbon, and (iv) mineral sequestration by lime. Local soil from the mine site was used as a control. Results show soil fertility parameters of the Technosols according to Brazilian guidelines. Plant growth increased with biochar incorporation but was still lower than in control soil. The pH, chemical, and mineralogical composition data were combined with geochemical reactions, showing the interaction of coal waste compounds, mainly pyrite with lime. Regarding calculating the CO2 capture potential, biochar and mineral carbonation were the most relevant means for the designed system. The best performance obtained can capture approximately 65 t CO2eq ha−1, about four times greater than the systems traditionally used to recover waste disposal areas. The study demonstrates the feasibility of incorporating mining site recovery, waste disposal, and emissions mitigation in a closed system, providing sustainable options for the coal mining industry.

A review on abiotic stress vulnerability of wheat and its management in Terai, Nepal

Wheat being one of the most important crops of Nepal after rice and maize is prone to abiotic stresses like heat and drought stress. Climate change, increasing temperature and decreasing precipitation is found to be the major cause of drought and heat stress, especially making developing countries like Nepal to be most vulnerable to the negative impacts on productivity and sustainability. Abiotic stress imposes devastating changes on morphology, biochemistry and physiological processes of wheat. Loss in seed vigor, decrease in germination rate, poor crop stand and abnormal embryo are common impact seen due to combined Abiotic stress. Though many trial has been performed on effect of heat and drought, there is a need for trial imposing wheat to combined stress environment. This review especially deals with the impacts of Abiotic stress along with management including tolerant varieties such as Bhrikuti, NL1420, BL4669, NL1350 and NL1368 and agronomic techniques like mulching, use of early varieties, early sowing and incorporation of Biochar.

Biochar and Straw Amendments over a Decade Divergently Alter Soil Organic Carbon Accumulation Pathways

Exogenous organic carbon (C) inputs and their subsequent microbial and mineral transformation affect the accumulation process of soil organic C (SOC) pool. Nevertheless, knowledge gaps exist on how different long-term forms of crop straw incorporation (direct straw return or pyrolyzed to biochar) modifies SOC composition and stabilization. This study investigated, in a 13-year long-term field experiment, the functional fractions and composition of SOC and the protection of organic C by iron (Fe) oxide minerals in soils amended with straw or biochar. Under the equal C input, SOC accumulation was enhanced with both direct straw return (by 43%) and biochar incorporation (by 85%) compared to non-amended conventional fertilization, but by different pathways. Biochar had greater efficiency in increasing SOC through stable exogenous C inputs and inhibition of soil respiration. Moreover, biochar-amended soils contained 5.0-fold greater SOCs in particulate organic matter (POM) and 1.2-fold more in mineral-associated organic matter (MAOM) relative to conventionally fertilized soils. Comparatively, although the magnitude of the effect was smaller, straw-derived OC was preserved preferentially the most in the MAOM. Straw incorporation increased the soil nutrient content and stimulated the microbial activity, resulting in greater increases in microbial necromass C accumulation in POM and MAOM (by 117% and 43%, respectively) compared to biochar (by 72% and 18%). Moreover, straw incorporation promoted poorly crystalline (Feo) and organically complexed (Fep) Fe oxides accumulation, and both were significantly and positively correlated with MAOM and SOC. The results address the decadal-scale effects of biochar and straw application on the formation of the stable organic C pool in soil, and understanding the causal mechanisms can allow field practices to maximize SOC content. These results are of great implications for better predicting and accurately controlling the response of SOC pools in agroecosystems to future changes and disturbances and for maintaining regional C balance.

Simultaneous regulation of nitrogen, sulfur and carbon using biochar during sewage sludge pyrolysis

Due to the complex nature of sewage sludge (SS), how to control the emission of precursor pollutants during its pyrolysis remains a challenge. In this work, the evolution of N, S and C during SS pyrolysis was investigated and biochars were employed to regulate their distribution in the resulting products. The release of N-containing products followed a descending order of NH3>HCN > NO > NO2 and the biochar addition resulted in a reduction of 40.7–54.3 % for these volatiles. The nitrile-N and pyrrolic-N species decreased, while the quaternary-N in residue increased significantly. The emission of S-containing products showed a descending order of COS > SO2>CH3SH > H2S > CS2 and the co-pyrolysis with biochar showed a reduction of 40.6–65.7 % for these products. The relative contents of thiophene-S and sulfoxide-S species increased, while the content of sulfone-S decreased. Biochar incorporation also resulted in a reduction of 67.2 % and 47.4 % for CO and CO2, respectively. Both Raman and XPS analysis indicated an increase in the graphitization degree and a decrease in structural defects.

Lactuca sativa Growth and Yield as Affected by Cashew Nut Shells Biochar, Cattle Manure and Urea in Northern and Central Benin

Aims: This study aims to identify good combinations of cashew nut shell biochar, cattle manure, and urea for enhancing lettuce (Lactuca sativa L.) growth and yield in the North and Central regions of Benin. Place and Duration of Study: Two agronomic trials were conducted: one in Tchaourou, Borgou department (2022), and another in Dassa, Colline department (2023). Methodology: A Fisher experimental design with three replications was used at each site, focusing on fertilization with seven treatments, including four reference treatments (local practices) and three treatments based on the reference treatments with biochar incorporation. Results: The results demonstrated significant improvements in plant growth parameters and yield, with the application of biochar combined with cattle manure and urea or with cattle manure only. The plants leaves number, height and yields obtained from the application of 10 t ha⁻¹ biochar + 20 t ha-1 cattle manure and 10 t ha-1 biochar + 0.025 t ha-1 urea +10 t ha-1 cattle manure were respectively at least 165 and 318%; 25 and 50%; 42 and 91% higher than those obtained under the producer's mineral fertilization practice at both sites. Conclusion: The findings showed that integrating cashew nut shell biochar with organic and inorganic fertilizers can significantly enhanced lettuce production, and thus overall vegetable crop yields while reducing the need for mineral fertilizers and dependence of cattle manure. Additionally, studying the best application methods and rates for different soil types and crop systems can help in maximizing the benefits of biochar.

Biochar mitigates the stimulatory effects of straw incorporation on N2O emission and N2O/(N2O + N2) ratio in upland soil

Straw incorporation, a common agricultural strategy designed to enhance soil organic carbon (SOC), often leads to increased nitrous oxide (N2O) emission, potentially offsetting benefits of SOC sequestration. However, the mechanism and mitigation options for the enhanced N2O emission following straw incorporation remain unclear. Here, N2 and N2O emission rate, as well as N2O/(N2O + N2) ratio under four different fertilization treatments [i.e., non-fertilization (Control), conventional chemical fertilization (CF), conventional chemical fertilization plus straw incorporation (SWCF), and conventional chemical fertilization plus straw and biochar incorporation (SWBCF)] were investigated by a robotized sampling and analysis system. High-throughput sequencing was also employed to assess the variation of bacterial community across different treatments. The results showed CF, SWCF, and SWBCF fertilization treatments significantly increased N2O emission rate by 1.04, 2.01, and 1.29 folds, respectively, relative to Control treatment. Albeit no significant enhancements in N2 emission rate, the N2O/(N2O + N2) ratio significantly increased by 65.53%, 1.10 folds, and 69.49% in CF, SWCF, and SWBCF treatments, respectively. The partial least squares path modeling analysis further revealed that fertilization treatments slightly increased N2 emission rate by increasing DOC content and keystone OTUs abundance. While the enhanced N2O emission rate and N2O/(N2O + N2) ratio in the fertilization treatments was primarily determined by reducing DOC/NO3− ratio and specific bacteria module abundance dominated by Gaiellales, Solirubrobacterales, and Micrococcales. Furthermore, SWBCF treatment alleviated the increase in net global warming potential due to straw incorporation, as indicated by the higher SOC sequestration and lower N2O/(N2O + N2) ratio therein. Collectively, these findings suggest that simultaneous application of straw and biochar has the potential to mitigate the risk of increased N2O emission from straw incorporation. This study provides valuable insights for developing targeted strategies in C sequestration and greenhouse gas mitigation, tackling the challenge presented by global climate change.

Tailoring the mechanical strength and corrosion resistance of aluminum matrix composites through biochar reinforcement at varied weight percentages

This study introduces an innovative approach to fabricate aluminum matrix composites strengthened with biochar, derived from renewable biomass sources. A systematic investigation of varying biochar weight percentages (0, 2.5, 5, 7.5, and 10 wt%) reveals substantial improvements in mechanical properties and corrosion resistance. Mechanical assessments, including compressive strength and hardness, demonstrate a significant enhancement in mechanical strength with biochar incorporation. In this study, it was discovered that the composite with 7.5 wt% biochar exhibits an optimal balance, displaying an 8.83% increase in compressive strength and a 15.15% rise in hardness compared to the base aluminum matrix. The study further evaluates corrosion behavior through electrochemical analyses and immersion tests in 3.5% NaCl corrosive environments, highlighting the superior corrosion resistance of biochar-reinforced composites. Corrosion rates decrease by 73% in the composite with 10 wt% biochar for the 24 h immersion time, affirming its protective barrier against corrosive agents. This research provides quantitative insights into tailoring mechanical and corrosion properties in aluminum matrix composites through biochar reinforcement, offering a promising avenue for sustainable material development. The resulting materials exhibit not only an 8.83% increase in mechanical strength but also a 73% reduction in corrosion rates, offering valuable uses in industries that need strong, eco-friendly solutions.

Straw-derived biochar regulates soil enzyme activities, reduces greenhouse gas emissions, and enhances carbon accumulation in farmland under mulching

Context or problemFilm mulching can significantly increase crop yields, but long-term continuous mulching will reduce the soil fertility and lead to soil quality degradation. Incorporating exogenous carbon (C) is widely recognized as an effective countermeasure for improving degraded farmland soil under mulching in semiarid areas. Objective or research questionWe compared the effects of straw and biochar on the accumulation of C and soil biochemical properties in both mulched and non-mulched farmland, and investigated the effects of various types of straw inputs on greenhouse gas (GHG) emissions. MethodsA field experiment was conducted to test six treatments: flat planting without mulching (NN), flat planting with straw incorporation (NS), flat planting with biochar incorporation (NB), film mulching (MN), film mulching with straw incorporation (MS), and film mulching with biochar incorporation (MB)]. Comprehensive assessments were conducted in Pengyang, Ningxia, China during the two growing seasons of 2020 and 2021. ResultsMulching increased the soil hydrothermal conditions, maize yields (29.32 %), and GHG emissions (CO2: 10.07 %; N2O: 1.42 %) but decreased the soil organic C storage (SOCS: 6.91 %). Straw returning increased the plant fixed C (14.99 %), improved GHG emissions (CO2: 4.95 %; N2O: 4.33 %), and inhibited CH4 uptake (3.78 %). Compared with MS, MB reduced the GHG emissions (CO2: 9.93 %; N2O: 20.97 %) and net global warming potential (7.08 %), but increased the SOCS (SOCS: 3.42 %), C efficiency ratio (CER: 26.93 %), CH4 uptake (10.72 %), and soil enzyme activities (invertase: 6.48 %; urease: 13.76 %). ConclusionsIncorporating biochar rather than straw has greater potential for enhancing the soil enzyme activities and C use efficiency while also reducing the GHG emissions and net global warming potential caused by mulching in dryland farming. Implications or significanceIn this study, we comprehensively compared the effects of incorporating straw, film mulching, and biochar incorporation on C accumulation, GHG emissions, and maize yields in dryland farming. Our findings provide a scientific basis for achieving green and sustainable high-yield production in mulched dryland farming.

Using waste to improve the weak: Recycled seashell as an ideal way to regulate the interfacial transition zone in biochar-cement composites

The strategy of partially substituting cement with carbon-negative biochar to fabricate biochar-cement composites can represent a promising approach to reducing the carbon emissions of the construction industry. However, the detrimental impact on strength development from excessive biochar incorporation remains a significant challenge. To address this issue, this study pioneers a strategy to modify wood waste-derived biochar using seashell waste for enhancing its binding with the cement matrix. Employing a mechanochemical process, the shell-modified biochar was synthesized using oyster shell (OS) and wood waste (WW). The compressive strength of cement composites incorporating 5 wt% modified biochar improved by 3.9–17% compared to the referenced biochar. Even with high biochar incorporation (30 wt%), the compressive strength increased by 58.2% upon modifying the biochar at the OS/WW ratio of 1:9 (10SBC). The modified biochar refined the pore structures, accelerated the hydration kinetics, improved the degree of hydration, and fostered the development of the C-S-H gel network with a longer silicate chain and a higher polymerization degree. Furthermore, the strength enhancement of the biochar-cement composites was attributed to the improved micro-mechanical properties at the interfacial transition zone (ITZ), which increased the volume fraction of high-density C-S-H by 64.4–112% and decreased the low-density C-S-H fraction by 41.8–52.6%. Notably, 10SBC demonstrated a superior improvement due to its cohesive bond with the C-S-H gel and the concurrent densification of C-S-H in the ITZ, which was facilitated by the growth of Ca-/Al-rich hydration products. Overall, this study synergistically upcycled wood and seashell waste into value-added cement additives, thereby achieving strength enhancement of the cement composites.

How much biochar is safe? Exploring potential ecotoxicological consequences for soil invertebrates and plants

The application of biochar in soil has shown promising potential for mitigating the toxicity of contaminated soils due to its unique properties. However, the understanding of its adverse effects on soil biota remains limited. This study aimed to investigate the potential ecotoxicological effects of incorporating sugarcane straw biochar into clay and sandy soils. This research assessed three biochar dosages (2 %, 5 %, and 10 %) and their effects on four species: the springtails Sinella curviseta and Proisotoma minuta, the worm Enchytraeus crypticus, and the plant Eruca sativa L. The results revealed that biochar incorporation had positive effects on plant growth, increasing biomass, and shoot and root length in E. sativa, with more pronounced effects in clay soil. However, the effects on the survival, reproduction, and growth of springtails varied depending on the species and soil type, with a reduction in the survival of P. minuta in both soils (2,2 and 2,9 times lower in clay soil and sandy soil respectively) and S. curviseta only in clay soil (24 % to 36 % decrease). The reproduction of P. minuta decreased in both soils (34 % - 48 % in sandy soil and 50 % - 80 % in clay soil), while the reproduction of S. curviseta decreased only at the lowest proportion of biochar in the clay soil (18 % decrease). For E. crypticus, biochar improved both survival and reproduction, especially in sandy soil (1.9 and 11 times greater respectively). Therefore, biochar has positive effects on worms and plants, indicating the potential to improve soil health and support ecosystem resilience, but it has deleterious effects on springtails at certain dosages. The effects of biochar amendments on soil characteristics and the effects of biochar-induced toxicity should be considered to avoid potential risks to representative species. The findings presented herein address lacunae in ecotoxicology by delineating safe concentrations of biochar for various soil species, thus paving the way for subsequent validation of optimal application doses.

Incorporating straw‐derived biochars enhances soil nitrogen accumulation and mitigates nitrogen leaching to facilitates crop productivity of mulching farmland in semiarid regions

AbstractThe long‐term use of film mulching and conventional chemical fertilizers in semiarid regions has resulted in soil degradation and suboptimal fertilizer utilization, necessitating a reevaluation of agricultural practices to enhance resource utilization efficiency and ensure the sustainability of dryland crop production. We conducted a 5‐year study (2017–2021) field experiment in northwest of China, to assess the impact of straw or biochar incorporation on soil water accumulation, crop nitrogen transport, and maize yield under film mulching field. The experiment had six treatments (flat planting without mulching [NN], flat planting with straw incorporation [NS], flat planting with biochar incorporation [NB], film mulching [MN], film mulching with straw incorporation [MS], and film mulching with biochar incorporation [MB]). We undertook a comprehensive assessment over the two growing seasons in 2020–2021. The film mulching and straw/biochar treatments improved soil water storage. The MB treatment significantly decreased 60–200 cm soil NO3−‐N content by 28.37% compared with MN. Biochar incorporation significantly increased soil total and alkali‐hydrolyzable N contents, whereas MS decreased soil alkali‐hydrolyzable N content compared with MN. The maize plant N transportation and grain contribution rates were significantly higher under MS (17.46% and 29.84%) and MB (28.00% and 31.69%) than under MN, respectively. Straw and biochar incorporation significantly increased water use efficiency, nitrogen fertilizer recovery efficiency, and maize yield, on average, by 9.62%, 9.14%, and 14.6%, respectively. In conclusion, incorporating biochar, in particular, positively mitigated N losses, enhanced N utilization efficiency, and increased maize yield in long‐term film mulching farmland in semiarid region.

Magnesium-doped biochars increase soil phosphorus availability by regulating phosphorus retention, microbial solubilization and mineralization

Despite fertilization efforts, phosphorus (P) availability in soils remains a major constraint to global plant productivity. Soil incorporation of biochar could promote soil P availability but its effects remain uncertain. To attain further improvements in soil P availability with biochar, we developed, characterized, and evaluated magnesium-oxide (MgO) and sepiolite (Mg4Si6O15(OH)2·6H2O)-functionalized biochars with optimized P retention/release capacity. Field-based application of these biochars for improving P availability and their mechanisms during three growth stages of maize was investigated. We further leveraged next-generation sequencing to unravel their impacts on the plant growth-stage shifts in soil functional genes regulating P availability. Results showed insignificant variation in P availability between single super phosphate fertilization (F) and its combination with raw biochar (BF). However, the occurrence of Mg-bound minerals on the optimized biochars’ surface adjusted its surface charges and properties and improved the retention and slow release of inorganic P. Compared to BF, available P (AP) was 26.5% and 19.1% higher during the 12-leaf stage and blister stage, respectively, under MgO-optimized biochar + F treatment (MgOBF), and 15.5% higher under sepiolite-biochar + F (SBF) during maize physiological maturity. Cumulatively, AP was 15.6% and 13.2% higher in MgOBF and SBF relative to BF. Hence, plant biomass, grain yield, and P uptake were highest in MgOBF and SBF, respectively at harvest. Optimized-biochar amendment stimulated microbial 16SrRNA gene diversity and suppressed the expression of P starvation response and P uptake and transport-related genes while stimulating P solubilization and mineralization genes. Thus, the optimized biochars promoted P availability via the combined processes of slow-release of retained phosphates, while inducing the microbial solubilization and mineralization of inorganic and organic P, respectively. Our study advances strategies for reducing cropland P limitation and reveals the potential of optimized biochars for improving P availability on the field scale.Graphical

Enhancing Photocatalytic Activity for Solar‐to‐Fuel Conversion: A Study on S‐Scheme AgInS2/CeVO4@Biocharx Heterojunctions

AbstractRare earth vanadates are promising for solar‐to‐fuel conversions, yet their photocatalytic efficiency is limited by the substantial recombination of photo‐generated carriers. Constructing heterojunctions is recognized as an effective approach to improving charge carrier separation in vanadates. Nonetheless, inefficient charge transfer often results from the poor quality of interfaces and non‐directional charge transfer within these heterojunctions. Herein, an S‐scheme AgInS2/CeVO4@Biocharx (AIS/CV@Cx) heterojunction photocatalyst is designed and synthesized through a straightforward freeze‐drying and calcination three‐step process, aimed at photocatalytic co‐production of xylonic acid and carbon monoxide (CO) from xylose. The AIS/CV@C2 heterojunction achieves an optimal yield of 67.74% for xylonic acid and a CO release of 29.76 µmol from xylose. The enhanced photocatalytic performance of the AIS/CV@C2 heterojunction is attributed to three key factors: I) the high‐quality interface and intimate contact within the AIS/CV@C2 heterojunction significantly reduce undesirable carriers recombination, II) the staggered band structures and directed carriers transfer in the AIS/CV@C2 heterojunction notably improve spatial carriers separation/migration, and III) the incorporation of biochar boosts the conductivity of the AIS/CV@C2 heterojunction. This work presents a straightforward yet effective method for fabricating vanadate heterojunctions, highlighting the importance of quality interfacial contact and directed charge transfer in amplifying photocatalytic performance.

Incorporation of compost and biochar enhances yield and medicinal compounds in seeds of water-stressed Trigonella foenum-graecum L. plants cultivated in saline calcareous soils

BackgroundThe combination of compost and biochar (CB) plays an important role in soil restoration and mitigation strategies against drought stress in plants. In the current study, the impact of CB was determined on the characteristics of saline calcareous soil and the productivity of fenugreek (Trigonella foenum-graecum L.) plants. The field trials examined CB rates (CB0, CB10 and CB20 corresponding to 0, 10, and 20 t ha‒1, respectively) under deficit irrigation [DI0%, DI20%, and DI40% receiving 100, 80, and 60% crop evapotranspiration (ETc), respectively] conditions on growth, seed yield (SY), quality, and water productivity (WP) of fenugreek grown in saline calcareous soils.ResultsIn general, DI negatively affected the morpho-physio-biochemical responses in plants cultivated in saline calcareous soils. However, amendments of CB10 or CB20 improved soil structure under DI conditions. This was evidenced by the decreased pH, electrical conductivity of soil extract (ECe), and bulk density but increased organic matter, macronutrient (N, P, and K) availability, water retention, and total porosity; thus, maintaining better water and nutritional status. These soil modifications improved chlorophyll, tissue water contents, cell membrane stability, photosystem II photochemical efficiency, photosynthetic performance, and nutritional homeostasis of drought-stressed plants. This was also supported by increased osmolytes, non-enzymatic, and enzymatic activities under DI conditions. Regardless of DI regimes, SY was significantly (P ≤ 0.05) improved by 40.0 and 102.5% when plants were treated with CB10 and CB20, respectively, as similarly observed for seed alkaloids (87.0, and 39.1%), trigonelline content (43.8, and 16.7%) and WP (40.9, and 104.5%) over unamended control plants.ConclusionsOverall, the application of organic amendments of CB can be a promising sustainable solution for improving saline calcareous soil properties, mitigating the negative effects of DI stress, and enhancing crop productivity in arid and semi-arid agro-climates.

Soil carbon sequestration increment and carbon-negative emissions in alternate wetting and drying paddy ecosystems through biochar incorporation

Biochar has been recognized as one of the most important negative emission technologies due to its indirect removal of atmospheric carbon dioxide. However, how biochar incorporation converts rice paddy into carbon negative and enhances soil carbon sequestration (SOCS) remain largely unexplored, especially under alternate wetting and drying irrigation (IAWD). A 3-yr field experiment was conducted utilizing a split-plot design with continuous flooding irrigation (ICF) and IAWD as main plots and two biochar incorporations at the rate of 0 t ha−1 (B0) and 20 t ha−1 (B20) as sub-plots. Results indicated that IAWD reduced CH4 emissions by 73 %, GWP by 69 %, and greenhouse gas emission intensity (GHGI) by 69 % on average, but increased N2O emissions by 109 % over the three years. Biochar inhibited N2O emissions by 31 % over the three years, increased grain yield by 5 % and 11 %, and reduced CH4 emissions by 22 % and 38 % in the 2nd and 3rd year, although a 6 % lower grain yield was observed in the 1st year. Biochar can increase SOCS and SOCS rate more remarkably under IAWD than ICF. Biochar coupled with IAWD obtained the highest SOCS (56.9 t C ha−1) and lowest net GWP (-23.0 t CO2-eq ha−1) and efficiently inhibited the negative effect of IAWD on the increase in N2O emissions. Moreover, compared with ICFB0, ICFB20 and IAWDB20 decreased net GWP by nearly 4 and 8 times, which was mainly attributed to a substantial increase in SOCS (48.3 and 56.9 t C ha−1) through biochar incorporation. The further decline in net GWP comparing IAWDB20 with ICFB20 was caused by decreased GWP under IAWD. Therefore, biochar combined IAWD offers significant benefits in mitigating net greenhouse gases emissions and promoting soil C sequestration in paddy ecosystems.