Biochar Addition Research Articles

Efficient Hydrodeoxygenation of Lignin-Derived Phenolic Compounds Over Ru-Based Catalyst with Biochar and Al2O3 as Composite Support.

Hydrodeoxygenation (HDO) is a common strategy for upgrading lignin-derived phenolic compounds into high-quality liquid fuels, and the support rational design of HDO catalysts is critical to achieve a good reaction performance. This work proposed a novel Ru-based catalyst with biochar and Al2O3 as composite support. The addition of biochar can enlarge the porous structure, and the addition of Al2O3 can enhance the acid property of the support. By regulating the content of biochar and Al2O3 components, Ru/CA-2 catalyst achieved the best HDO performance of lignin-derived phenolic compounds, with the optimal component balance of 50 %C and 50 %Al2O3. This catalyst possesses the high Ru metal dispersion (1.38 nm particle size) to activate the hydrogen source, the moderate acid property to suppress carbon deposition and the abundant oxygen vacancy to promote substrate adsorption at the same time. 99.9 % conversion of guaiacol is obtained at 230 °C, with 99.9 % selectivity towards cyclohexane. Ru/CA-2 catalyst also has a good recyclability, with no obvious activity loss after five runs. Furthermore, in the application of catalytic lignin-oil HDO, the content of hydrocarbons increase from 10.7 % to 95.7 %, showing great potential on the industrial usage.

Lipase pretreatment enhances biochar‐assisted anaerobic digestion of food waste

AbstractAnaerobic digestion is a promising technology for the treatment of food waste (FW) but it requires optimization to improve its performance. This study investigated whether combining the addition of biochar with lipase pretreatment could improve the anaerobic digestion of FW. The results showed that biochar stimulated the release of soluble substances, resulting in an increase in the methane yield of groups with added biochar by 16.24% to 19.36% in comparison with the group without biochar. Lipase pretreatment substantially shortened the fermentation time required to complete the anaerobic digestion, from 15 to 9 days. Lipase pretreatment further improved microbial abundance and promoted the enrichment of functional microbes in the anaerobic digestion of FW mediated by biochar. It also changed the methane production pathway from acetotrophic to hydrogenotrophic, thereby ensuring the stability of the anaerobic digestion system in the presence of a high ammonia nitrogen concentration.

Cr(VI) bioreduction enhanced by the electron transfer between flavin reductase and persistent free radicals.

Persistent free radicals (PFRs) in biochar are an important electron shuttle for mediating electron transfer, which has significant impact on the biogeochemical redox reactions. Although the influence of biochar on the extracellular electron transfer (EET) for redox cycle has been extensively studied, the molecular mechanism for promoting the EET with PFRs remains poorly understood. This study investigated the oxygen-centered PFRs-mediated Cr(VI) reduction by Shewanella oneidensis MR-1 (MR-1) and exhibited the molecular mechanism of electron transfer between flavin substances and PFRs. Results showed that the Cr(VI) bioreduction rate by MR-1 increased from 31% to 70% with the addition of biochar. Electrochemical results illustrated that biochar increased biocurrent generation in the Cr(VI) bioreduction process. 3D-EEM and LC/MS spectra indicated that MR-1 secreted the flavin mononucleotide (FMN) reductase that relied on the [H] to provide the electrons. Electron paramagnetic resonance spectra illustrated that PFRs in biochar accepted the electrons from FMN reductase and stored those bioelectrons. Because of the oxidation of FMN, the electron transfer from FMN reductase to PFRs would increase the intracellular reactive oxygen species, which further produced the extracellular ·O2-. The reduced PFRs released the bioelectrons, accelerating the Cr(VI) reduction by ·O2-. Together with the results of the mutant strains experiment, it was found that the EET by c-cytochrome and free radicals contributed to the Cr(VI) bioreduction by 7.1% and 92.9%, respectively. These findings revealed that the PFRs could participate in the EET process and promote the redox reactions, providing a new approach for enhancing the remediation of heavy metal pollution by microorganisms and suggesting the important role of PFRs in the electron transfer process.

Evaluation of Soil Texture, EC, pH and Primary Macro Elements in Five Mango Orchard Soils of Kotri, Sindh, Pakistan

Analysis of soil is a very important practice for evaluating the nutrient status and ultimately establishing the fertilizer application program for soil health, fruit quality and production. The aim of present study was to assess the soil texture, electrical conductivity (EC), pH, and primary macronutrients such as N, P, K at 0-15 and 15-30cm depths from five orchards such as Aijaz farm (Orchard 1), Zardari farm (Orchard 2), Shahnawaz farm (Orchard 3), Ismail farm (Orchard 4), and Malik Azad farm (Orchard 5) of Kotri, Sindh Pakistan. The results indicated that most of the soils were sandy clay loam in textural class. The maximum electrical conductivity was found 0.65 dS m-1 in orchard 5, whereas the lowest electrical conductivity was found as 0.42 dS m-1 in orchard 1 at 15-30cm. All the orchards were found alkaline in nature at both 0-15 and 15-30cm depths. The total N content was found 80% low and 20% adequate at 0-15cm depth and 100% orchards were found low in total N content in soil at 15-30cm depth as compared with standard values. The AB-DTPA-P content in orchards were found 60% marginal and 40% adequate at 0-15cm depth, whereas 20% low, 40% marginal and 40% adequate were found at 15-30cm depth. AB-DTPA-K (mg kg-1) was found 20% low and 80% marginal at 0-15 and 15-30cm depths. Future studies should focus on assessing the soil biological properties, plant analysis, soil interaction mechanism, amended with press mud compost, farmyard manure, biochar, modified biochar, nano-material, minerals and low-cost additives.

Effects of Biochar on the Growth and Physiological and Mechanical Properties of Cucumber Plug Seedlings Before and After Transplanting

Since the characteristics of plug seedlings affect the effectiveness of automatic transplanting, this study aimed to explore the effect of the addition of biochar into substrates on the growth of plug seedlings before and after transplanting. The physicochemical properties of substrates with 0%, 5%, 10%, 15%, 20%, and 25% biochar addition all met the requirements of seedling cultivation. The growth trend, root systems, and mechanical properties of seedlings before transplanting and the leaf gas exchange parameters of seedlings after transplanting were measured in this study. The results indicated that the seedlings cultivated with 10% biochar added to the substrate achieved the best growth trend and physiological indices, and the root systems under this treatment were also stronger than those of other treatments, while the seedlings cultivated with 25% biochar treatment were the worst, with less than 22.23% of the growth seen in the 10% biochar treatment, and even less than 1.5% of the growth of the seedlings cultivated without biochar treatment. Since the strong root systems could enhance the mechanical properties of seedling pots, the seedling pots cultivated with 10% biochar added into the substrate possessed the best compression resistance properties, with the maximum value of 49.52 N, and could maintain maximum completeness after free-fall impacting, wherein the loss of root and substrate was only 8.22%. The analysis results of seedlings cultivated after impacting proposed that the seedlings with better growth trends and root systems before transplanting could obtain better leaf gas exchange parameters during the flower stage after transplanting, so the seedlings cultivated with 5%~10% biochar added into the substrate grew better after impacting and then transplanting. It was noticed that the seedlings cultivated with appropriate biochar added into the substrate were able to achieve the optimal growth parameters and mechanical properties before and after transplanting, which were better able to meet the requirements of automatic transplanting. Thus, this study can promote the development of automatic transplanting technology to some extent.

The Effect of Biochar on Tomato (Solanum lycopersicum) Cultivar Micro-Tom Grown under Continuous Light

AbstractContinuous lighting (CL) has the potential to increase crop yield in greenhouse production. Tomato plants, however, when exposed to CL develop inter-vascular chlorosis, a leaf injury which causes a reduction in chlorophyll content and necrosis. The application of biochar can reduce physiological stress in plants, we examine if biochar also reduces necrosis in tomatoes when grown under CL. Faecal sludge biochar was applied to an acidic soil to examine plant growth and yield in Micro-Tom tomato plants grown under continuous light. We examined soil and plant growth properties of three soil application treatments: a control soil, biochar treatment (4%w/w) (Biochar), and a combined biochar (2% w/w) and fertilizer (2% w/w) treatment (Biochar + Fert). Faecal sludge biochar addition produced plant heights 216% greater than control and above ground biomass 583% greater than control. The biochar and fertilizer treatment group produced a 487% increase in leaf number compared to biochar. The combined biochar and fertilizer treatment produced a 398% increase in dried above ground biomass and a 177% increase in dried fruit yield compared with biochar. Plants in the biochar and fertilizer treatment group showed less visual evidence of continuous light induced leaf injury.Biochar addition did not limit continuous light induced leaf chlorosis whereas combined biochar and fertilizer treatment resulted in a significant reduction in leaf injury and death. Overall, the application of biochar and biochar and fertilizer combined increased crop yield.

Above and belowground functional trait response to biochar addition in seedlings of six tropical dry forest tree species

Above and belowground functional trait response to biochar addition in seedlings of six tropical dry forest tree species

Effect of biochar on the co-conversion of carbon-nitrogen and humification of kitchen waste composting process

Composting was an effective technique to treat kitchen waste into high-quality fertilizer or soil amendment. During the composting process of kitchen waste, different degradation rates of carbon and nitrogen resulted in carbon loss, nitrogen emission and low product quality. Consequently, the aim of this study was to investigate the mechanisms and effects of biochar (5%, 10% and 15%) on synergistic conversion of nitrogen and carbon and humification processes in kitchen waste composting. The findings revealed that the addition of 10% and 15% biochar prolonged the thermophilic phase (>55°C) by a minimum of three days compared to CK. Additionally, the final NH4+-N concentration in the 10% and 15% treatment groups exhibited a 66.7% reduction in comparison to the control. Besides, the 15% addition proved more efficacious in reducing the NH4+-N content. The increase in biochar facilitates the adsorption of ammonia nitrogen and influences the structure of the microbial community, especially Bacteroides and Pseudoxanthomonas, thus promoting nitrogen mineralisation and humification, which provides energy and carbon for the survival and metabolism of more microorganisms. The compost with 15% biochar exhibited higher levels of SBR1031, resulting in a 73.8% increase in the conversion of nitrogen to NO3--N compared to the control. The aforementioned behaviour facilitates a synergistic conversion of nitrogen and carbon. Therefore, the addition of biochar promotes synergistic carbon and nitrogen transformations in terms of nitrogen conservation, organic matter decomposition, microbial species and their interactions, which is essential for the production of value-added compost fertilizers.

Biochar addition mitigates asymmetric competition of water and increases yield advantages of maize–alfalfa strip intercropping systems in a semiarid region on the Loess Plateau

ObjectiveUnbalanced competition for water poses a major challenge to intercropping systems in semiarid regions. The role of biochar as a soil amendment in regulating water balance and crop productivity is unclear. MethodsIn this two-year field trial, we investigated the impact of biochar application and method on the relationship between water balance utilization and productivity in maize–alfalfa strip intercropping. Monocropping [sole maize (SM) and sole alfalfa (SA)] and intercropping (I) systems were established, with biochar added to corresponding treatments (SMc, SAc, and Ic) and solely to intercropping alfalfa and maize (IAc and IMc). Results and conclusionsOur findings reveal that the yield of the intercropping system (I) was 11.4 % higher than expected on average. Biochar addition significantly increased forage production and water use efficiency, with similar benefits observed in monocropping systems. While competition ratio (CR) values reduce also reducing competition between maize and alfalfa. In two years, applying biochar solely to alfalfa (IAc) resulted in a higher land equivalent ratio (LER) and water equivalent ratio (WER) of 8.63 % and 12.73 %, respectively, compared with applying biochar solely to maize (IMc). Notably, yield and water use efficiency (WUE) increased the most when biochar was applied to intercropped maize and alfalfa (Ic), increasing by 16.1 %–16.6 % and 6.7 %–10.3 % compared with I, resulting in an increase in economic benefits by 24.9 %–26.3 %. Different biochar application methods showed significant potential in mitigating water competition in intercropping, with both sole and joint applications improving WUE, with the latter (Ic) demonstrating the most pronounced effect. However, excessive soil water consumption poses risks of water overuse, emphasizing the need to balance biochar utilization with water resource management. SignificanceOur findings highlight the ability of biochar to alleviate water competition imbalances and optimize water use in intercropping, providing a new approach for efficient water use in semiarid rain-fed agricultural systems.

Biochar affects soil properties over 1 m depth in an alkaline soil of north China Plain

Biochar has been shown to enhance soil quality and agricultural yields. Previous studies about biochar's effect on soil properties mainly concentrated on the top 30 cm layer but less on the subsoils. Given the subsoil's active role in climate change mitigation and its significance for nutrient cycling and crop productivity, understanding biochar's effects at depth is crucial. This study explored the responses of soil organic carbon (SOC), total nitrogen, available potassium, available phosphorus, pH, and electrical conductivity to different doses of biochar addition (0, 10, 20, and 30 Mg/ha) over the 1 m depth of alkaline soil. Additionally, the impact of biochar on soil microbial community was assessed in the top 20 cm. Results demonstrated that biochar addition can increase SOC and improve soil properties in deep soil horizons. Specifically, a 30 Mg/ha biochar addition increased SOC by 1.2–10.1 Mg C/ha in the 10–40 cm layer and by 3 Mg C/ha in the 60–80 cm depth over two years. Additionally, biochar addition at this rate increased total nitrogen by 0.2–0.3 g N/kg in the 10–40 cm depth and elevated available potassium across the 1 m profile, with a maximum increment of 313 mg/kg in the surface 10 cm and a minimum of 97 mg/kg in the 40–60 cm depth. While biochar application did not increase available phosphorus, it resulted in a minor decrease in soil pH (<0.7 units) and a slight increase in electrical conductivity. Moreover, biochar addition did not significantly alter the soil microbial community. Our findings underscore the importance of considering subsoils when evaluating biochar's impact on soil properties. We suggest that subsoils should be considered when estimating the potential of cropland management for increasing soil carbon sequestration and improving soil conditions.

Co-applied biochar and drought tolerant PGPRs induced more improvement in soil quality and wheat production than their individual applications under drought conditions.

Plant growth and development can be greatly impacted by drought stress. Suitable plant growth promoting rhizobacteria (PGPR) or biochar (BC) application has been shown to alleviate drought stress for plants. However, their co-application has not been extensively explored in this regard. We isolated bacterial strains from rhizospheric soils of plants from arid soils and characterized them for plant growth promoting characteristics like IAA production and phosphate solubilization as well as for drought tolerance. Three bacterial strains or so called PGPRs, identified as Bacillus thuringiensis, Bacillus tropicus, and Bacillus paramycoides based on their 16S rRNA, were screened for further experiments. Wheat was grown on normal, where soil moisture was maintained at 75% of water holding capacity (WHC), and induced-drought (25% WHC) stressed soil in pots. PGPRs were applied alone or in combination with a biochar derived from pyrolysis of tree wood. Drought stress substantially inhibited wheat growth. However, biochar addition under stressed conditions significantly improved the wheat growth and productivity. Briefly, it increased straw yield by 25%, 100-grain weight by 15% and grain yield by 10% compared to the control. Moreover, co-application of biochar with PGPRs B. thuringiensis, B. tropicus and B. paramycoides further enhanced straw yield by 37-41%, 100-grain weight by 30-36%, and grain yield by 22-22.57%, respectively. The co-application also enhanced soil quality by increasing plant-available phosphorus by 4-31%, microbial biomass by 33-45%, and soil K+/Na+ ratio by 41-44%. Co-application of PGPRs and biochar alleviated plant drought stress by improving nutrient availability and absorption. Acting as a nutrient reservoir, biochar worked alongside PGPRs, who solubilized nutrients from the former and promoted wheat growth. We recommend that the co-application of suitable PGPRs and biochar is a better technology to produce wheat under drought conditions than using these enhancers separately.

Soil organic carbon, carbon fractions, and microbial community under various organic amendments

The impact of various organic amendments on soil organic carbon (SOC) have rarely been reported. To address this, a laboratory experiment was designed to scrutinize the effects of different amendments on soil carbon fractions, microbial communities, and the underlying interactive mechanisms. The experiment encompassed a no-amendment control (CK), as well as treatments with corn straw (CS), tobacco stalks (TS), and peanut shell biochar (PB). Over a 70-day incubation, the SOC in plots amended with CS, TS, and PB displayed significant boosts of 13.9%, 17.5%, and 44.8%, respectively, compared to the CK. For soil carbon fractions, amendments with PB, TS, and CS led to a dramatic rise in particulate organic carbon (POC) of 27.4%, 20.2%, and 105.7%, respectively, in contrast to the CK plots. Mantel analysis and structural Equation Modeling uncovered strong interrelationships among the cbbL, cbbM, Bacteroidota, TOC, and POC. Organic amendments enhance soil carbon fractions, modulating the microbial community by increasing Bacteroidetes abundance and suppressing Acidobacteria richness, thereby influencing the abundance of key carbon cycle genes such as cbbL and cbbM. These results suggest that the addition of peanut shell biochar significantly boosted TOC and key carbon fractions, enhancing carbon content and soil fertility.

The Comprehensive Effects of Biochar Amendments on Soil Organic Carbon Accumulation, Soil Acidification Amelioration and Heavy Metal Availability in the Soil–Rice System

In recent years, biochar (BC) and biochar-based soil amendments (CSAs) have been widely used in agriculture and the environment. In the present study, a two-rice-season field study was conducted to explore the comprehensive effects of applying BC (1%) and CSA (0.5% and 1%) on soil organic carbon accumulation, soil acidification amelioration and heavy metal availability in a soil–rice system. The results show that soil pH was increased by 0.5–1.7 units and 0.3–1.0 units, respectively, in the early rice season and late rice season treated by the amendments compared with CK. Soil organic contents were increased by 18–30% in the early rice season and by 15–25% in the late rice season in the amended treatments. In addition, soil available phosphorus contents were largely increased as a result of BC and CSA addition. Soil CaCl2 extractable heavy metals (Cd, Ni, Cu and Zn) were simultaneously decreased by BC or CSA amendments. In addition, Cd contents in early rice grain and late rice grain were significantly reduced by 25–48% and 52–83% in amended treatments, while Zn contents were generally not affected. The uptake of Cu and Ni was also decreased by BC and CSA. This study demonstrates that biochar application alone or combinates with inorganic amendments (limestone, sepiolite and potassium dihydrogen phosphate) can significantly improve soil properties and nutrient content and decrease the heavy metal (especially for Cd and Ni) uptake and accumulation from soil to rice grain, where the combination application is more effective.

The effect of leaf leachates addition on denitrification in subsurface flow constructed wetlands is shaped by the bed substrate type

In constructed wetlands (CWs), bed substrate and leaf leachates from vegetation may correct the low C/N ratio that constrains heterotrophic denitrification and nitrate removal from irrigated agricultural drainage water. However, the interactive effects of bed substrate type and leaf leachates on denitrification are still unknown. By focusing on a CWs pilot plant, we designed a laboratory experiment to evaluate i) wether denitrification potential rates varied among bed substrates: calcareous gravel (a conventional substrate), gravel+soil from a natural wetland (silty loam Solonchak, 1.5 % of organic C) and gravel+biochar from pyrolyzed ornamental plants (75 % of organic C); and ii) the response of denitrification within each bed substrate to the addition of their respective leaf leachates. We found that denitrification potential rates were lower in gravel beds (0.011 ± 0.006 μgN2O-N gDM−1 h−1) than those observed with the addition of biochar (0.06 ± 0.03) and especially soil (0.78 ± 0.04), with soil being the most advantageous option. Besides, leaf leachates addition boosted denitrification rates in all cases. Nevertheless, the effect of leachates was relatively higher in gravel beds than in the other substrates (15 times higher vs. 2 and 4 times with soil and biochar, respectively). Our outcomes highlight limited denitrification when using gravel substrate not only by low C but also due to essential macro- and micro-elements, and support the role of plant leaves as internal and self-sustainable source of nutrients.

Shift of bacterial and fungal communities upon soil amelioration is driven by carbon degradability of organic amendments

The structural response of bacterial and fungal soil communities to four carbon-rich organic amendments of increasing recalcitrance was investigated. Wheat straw, green compost, a mixed product based on biogas residues, and a fermented biochar were applied to a sandy agricultural soil of low organic carbon content. After laboratory incubation for 6 months, the community structure was investigated via DNA sequencing. All amendments caused changes in the communities of bacteria and fungi, but to different extents, with the communities exposed to more recalcitrant amendments showing the least variation compared to the non-amended soil. Changes in species composition as well as their relative abundances were observed. While the straw had a pronounced effect on bacteria (e.g., the highest number of indicator species), effects of the composted, fermented, or pyrolyzed materials were minor. Hierarchical clustering showed that the fungal communities were more different from each other than the bacterial ones with the straw-soil being most different and the biochar-soil least different from the non-amended soil. While the abundant fungal species in biochar-soil and non-amended soil were very alike, especially rare fungal species shifted upon addition of biochar. An indicator species analysis identified specific taxonomic groups which were triggered by the different organic materials. We conclude that bacterial and fungal communities strongly change upon input of degradable carbon (straw), while fungi in particular respond to the application of processed organic materials. With this study, we report the consequences of applying organic materials for the microbial community in one soil. We provide these data for meta-analyses that are required to unravel all relevant interactions across different soils, organic materials, and time. This will allow to better understand and predict the effects of organic soil amelioration measures on soil microorganisms.

Rape straw biochar-assisted preparation of flower-like BiOCl with enriched oxygen vacancies for efficient photocatalytic CO2 reduction and pollutants degradation

Utilizing photocatalytic technology to transform CO2 into high added value chemical products has represented an effective strategy for alleviating the climate problems that have arisen due to excessive CO2 emissions. As a typical bismuth-based photocatalyst, BiOCl has garnered widespread attention due to its unique layered structure and low toxicity. However, the low light utilization efficiency and the rapid recombination of e−/h+ pairs severely hinder the practical application of BiOCl. Introducing oxygen vacancies (OVs) into BiOCl has been demonstrated to be one of the effective strategies for enhancing the photocatalytic performance of BiOCl. However, introduction of OVs through a mild and cost-effective approach remains a significant challenge. In this work, we developed a strategy for introducing OVs on BiOCl, which indues the growth of BiOCl into flower-like spherical structures and introduction of abundant OVs through addition of rape straw biochar (RC) under hydrothermal conditions. The synergistic interaction of RC and OVs endows with BiOCl more active sites as well as higher photogenerated carriers (e−/h+) separation efficiency. When the mass ratio of RC to BiOCl is 0.5 % (RC-0.5), the sample demonstrates the best performance, conversion of CO2 to CO on the sample is 4.0 μmol g−1 h−1, which is 3.08 times higher than that on the reference BiOCl. Additionally, versatility of the photocatalysts was further evaluated through photocatalytic degradation of rhodamine B (RhB) and perfluorooctanoic acid (PFOA). The degradation rate constant of RhB and PFOA on the RC-0.5 sample is 0.0642 min−1 and 0.00566 min−1, respectively, which is 2.26 times and 0.43 times higher than that on the reference BiOCl. Total organic carbon (TOC) experiments demonstrate that RhB can be effectively mineralized into CO2, H2O and small molecules on the photocatalyst. The main reactive species involved in the photocatalytic degradation process were investigated through active free radical trapping experiments and electron paramagnetic resonance (EPR). This work provides a viable strategy for the development of high-performance BiOCl photocatalysts for environmental applications.

Evaluating the environmental and agronomic implications of bone char and biochar applications to loamy sand based on sorption data

BackgroundThe widely adopted use of charred biomass for agronomic and environmental purposes; and the reported positive and deleterious effects necessitated the need for this study to ascertain the potential causes of the erratic results surrounding the use of charred biomass in agriculture and the environment. A batch sorption experiment was carried out to determine the sorptive and desorptive capacity of bone char and biochar on nitrate, ammonium, phosphate and sulphate concentrations in a loamy sand soil. The potential agronomic and environmental implications of the sorption data were also discussed.ResultsThe results indicated that bone char is richer in nutrient composition than biochar, with 70% more ability to sorb nutrients. The bone char and biochar sorption isotherms conformed to the H-curve isotherm type. Bone char and biochar have multiple layers of adsorption sites. Nutrient adsorption maxima, binding energy, and maximum buffering capacities of the soil were increased with the addition of bone char and biochar. The unamended soil was observed to retain as low as 6% of added nitrate to as much as 58% of added phosphate, while bone char retained 56% of added sulphate, 47% of phosphate, 76% nitrate and 64% of ammonium. Generally, bone char retained 60.6% of the added nutrients, while biochar retained 40.7% of the nutrients. The addition of bone char led to a 45.8% increase in the nutrient retention ability of the soil and a 36.1% increase with the addition of biochar.ConclusionThe nutrient sorption characteristics of biochar should be studied prior to its use as a soil nutrient amendment. It was concluded that bone char or biochar is a potential soil nutrient immobilizer; hence, applications for agronomic purposes should take cognizance of the native soil fertility so as to appropriately add fertilizer input before use.

Biochar decreased N loss from paddy ecosystem under alternate wetting and drying in the Lower Liaohe River Plain, China

Biochar addition to soil is widely utilized to enhance carbon sequestration and reduce fertilizer N losses. However, little research has been studied on the effect of biochar on reactive gaseous N losses, N leaching and grain yield in paddy ecosystems under water stress, especially in the Lower Liaohe River Plain with a higher water percolation. Our experiment was carried out in 2020 and 2021 utilizing a split-plot design with continuously flooding irrigation and alternate wetting and drying irrigation as main plots and without biochar addition and with 20 t·ha−1 rice husk-derived biochar addition as sub-plots. The results showed that alternate wetting and drying irrigation respectively, decreased N leaching and reactive N losses by 15.9 % and 11.3 % but also respectively, increased seasonal cumulative NH3 volatilization and N2O emissions by 5.0 % and 210 % on average. Rice husk-derived biochar addition significantly mitigated seasonal cumulative NH3 volatilization and N2O emissions by 8.8 % and 19.7 % in 2020, 20.7 % and 19.2 % in 2021, respectively, and decreased inorganic N leaching and reactive N losses by 8.3 % and 14.1 % in 2021. Biochar addition coupling with alternate wetting and drying respectively, mitigated cumulative NH3 volatilization and N2O emissions by 7.3 % and 19.3 % in 2020, and, 22.7 % and 22.0 % in 2021 as compared to that without biochar. Biochar did not differ from without biochar in inorganic N leaching under alternate wetting and drying irrigation in both years but significantly reduced reactive N losses by 17.8 % in 2021, which efficiently inhibited the alternate wetting and drying induced negative effects on the increase in reactive N losses. Therefore, biochar addition to paddy ecosystems under alternate wetting and drying could realize sustainable utilization of water resources, increase soil N fixation, and mitigate N losses.

Biochar addition enhances remediation efficiency and rapeseed yield in copper-contaminated soil.

Soil contamination with copper (Cu) threatens ecological security and human health. Rapeseed demonstrates potential in remediating copper-contaminated soil, and biochar-assisted phytoremediation is increasingly being employed to improve remediation efficiency. However, the combined application of them has not been thoroughly studied in terms of the synergistic effects and the mechanisms of their interaction. In this regard, this study conducted a pot experiment to evaluate biochar-assisted remediation under Cu-contaminated soil with varying biochar application rates; Furthermore, the plant physiological mechanism and soil physicochemical properties involved in the biocharrapeseed system was explored. Our results showed that the exchangeable pool of copper in soil decreased by 10.0% and 12.3% with adding 5% biochar (BC1) and 10% biochar (BC2) relative to control (BC0), respectively, prior to rapeseed cultivation. The rapeseed cultivation for one season further reclaimed 4.9%, 9.0%, and 13.6% of the available copper in this soil by root extraction under the BC0, BC1, and BC2 treatments, respectively. The overall copper concentration in plants decreased by 23.7% under BC2 and 13.3% under BC1 compared to BC0. However, the plant's dry biomass at BC1 and BC2 treatments increased by 1.7-fold and 2.7-fold relative to BC0, which offset the negative impact of the decreased copper concentration on phytoremediation. Physiological analysis showed adding 10% biochar decreased the MDA content by 36% in the leaf and 49% in the root, compared to BC0. The transmission electron microscopy for cell wall ultrastructure in root tips showed that biochar addition in Cu-contaminated soil increased the mechanical strength of the celL wall, explicitly increasing the thickness of the secondary cell wall. Further cell wall components analysis revealed a remarkable increment of the pectin content in BC2 relative to BC0, increased by 56% in the leaf and 99% in the root, respectively. Additionally, 10% biochar application led to a roughly 2-fold increase in seed yield via ameliorating the soil physicochemical properties and increasing the rapeseed growth. These findings offer insights into synergistic rapeseed-biochar use for Cu-contaminated soil remediation.

Impact of biochar application on nitrous oxide and methane emissions in rainfed cropping systems within a semiarid region

AbstractThis study investigated the impact of biochar on Zea mays L. yield and greenhouse gas (GHG) emissions in rainfed maize fields in Northwest China. Four treatments were compared: unmodified control (CK), conventional nitrogen (BC0), nitrogen + 20 t ha−1 biochar (BC20), and nitrogen + 50 t ha−1 biochar (BC50). Results showed significant increases in grain yields with BC20 (11.1%) and BC50 (8.6%) compared to BC0. Emissions of nitrous oxide (N2O) were reduced by 14.0%–19.5% in biochar treatments compared to CK. Methane (CH4) uptake by the fields, acting as CH4 sinks, was not significantly impacted by biochar treatments, clarifying that the biochar did not alter the farmland's inherent ability to uptake CH4. Over 2 years, the addition of nitrogen fertilizer and biochar did not markedly alter cumulative CH4 uptake. Both net greenhouse gas (NGHG) emissions and yield‐scaled GHG intensity (NGHGI) were lowered by 16.7%–23.5% and 24.2%–30.3%, respectively, with biochar application. The integration of biochar effectively mitigated the GHG emission enhancement due to nitrogen fertilizer, mainly by decreasing nitrogen oxide emissions and boosting maize yields. Thus, proper biochar application would be an economical and effective strategy for mitigating gas emissions from rainfed maize cropping system in semiarid regions.