Effects Of Biochar Research Articles

Biochar as ammonia exchange biofilm carrier for enhanced aerobic nitrification in activated sludge

The effects of biochar on aerobic nitrification in activated sludge were investigated in sequencing batch reactors. Biochar amended reactors exhibited 87–94 % lower ammonia in effluent and 16–71 % greater removal of total Kjeldahl nitrogen compared to control reactors. Quantitative qPCR analyses revealed that the relative abundance of ammonia oxidizing bacteria (AOB, amoA/16S rRNA genes) was greater in biochar than in control reactors. AOB were enriched on biochar surfaces, with biochar particles having up to 12.1 times greater relative abundance of AOB compared to suspended biomass. Biochar’s maximum ammonia sorption capacity of 4.4 mg N/g at pH 7 decreased with decreasing pH, however a pH-sensitive fluorescent probe was used to show that biofilms growing on biochar surfaces maintain a median pH of > 6.7 despite reactor acidification by nitrification. Microbial colonization of biochar in activated sludge creates a pH-sheltered environment that sustains biochar’s ammonia sorption capacity, resulting in enrichment of AOB on biochar particles and improved nitrification.

Evaluation of Rheological Properties of Asphalt Binder Modified with Biochar from Oat Hulls.

In this study, the effect of biochar from oat hulls (BO) on the rheological properties of a PG 64-22 asphalt binder was evaluated using a full factorial design, which included the following factors: pyrolysis temperature (PT) (300 °C and 500 °C), BO particle size (<20 µm and <75 µm), and the amount of BO (2.5%, 5%, and 7.5%). First, the morphological and physicochemical properties of BO were analyzed by comparing it with graphite powder (CFG) and commercial activated carbon (CAC). The physicochemical properties of the modified asphalt binder were then evaluated using confocal laser microscopy, scanning electron microscopy (SEM-EDX), and Fourier-transform infrared spectroscopy (FTIR). Its storage stability was also evaluated. Subsequently, the rutting parameter G*/sin(δ) and the Fraass breaking point were analyzed to select asphalt binders that extended their viscoelastic range. The asphalt binders selected were those with 2.5%, 5%, and 7.5% BO, produced at a PT of 300 °C with a particle size <20 µm (BO300S). Next, the rheological properties of the selected samples were evaluated by testing for rotational viscosity, rutting parameter G*/sin(δ), multiple stress creep recovery (MSCR), fatigue parameter G*·sin(δ), and creep stiffness by bending beam rheometry (BBR). The rheological aging index according to rutting parameter G*/sin(δ) (RAI) was also evaluated. These tests were conducted in different states of the asphalt binder: original, short-term aged, and long-term aged. According to the results, the application of BO300S significantly increased the resistance of the asphalt binder to rutting and rotational viscosity, proportional to the amount added to the asphalt binder. Moreover, low modifier percentages improved fatigue resistance, outperforming CFG and CAC. In addition, it performs well at low service temperatures, registering better resistance than the control asphalt binders.

Effects of biochar and wood vinegar co-application on composting ammonia and nitrous oxide losses and fertility

Composting faces challenges with nitrogen (N) losses through ammonia (NH3) and nitrous oxide (N2O) emissions. In this study, wood vinegar (WV) and biochar (BC) were applied individually or combined into wheat straw and chicken manure composting. Results showed that BC and WV reduced NH3 volatilizations by 22–23 % individually, but their combined application achieved a 59 % reduction. However, this combination increased N2O emissions by 174 %. The BC + WV treatment improved compost quality, evidenced by increased total N content by 22 % and enhanced the biological index, promoting additional dissolved organic matter production. Overall, BC and WV applications improved compost quality, reduced gaseous N losses, and supported the re-utilization of agricultural residues. The combined use of BC and WV significantly enhances compost quality and reduces NH3 emissions, offering a promising solution for sustainable agricultural residue management.

Synergistic effect of salicylic acid and biochar on biochemical properties, yield and nutrient uptake of triticale under water stress

In arid regions, one of the practical solutions to overcome the water shortage and increasing soil fertility is application of salicylic acid (SA) with biochar. A pot experiment was conducted to consider the combination of SA with biochar on biochemical and physiological parameters of triticale as a factorial experiment using a completely randomized design (RCD) with four replicates. Treatments consisted of irrigation regime (normal irrigation and irrigation according to 50 % field capacity), salicylic acid application [without SA (SA0) and 3 mM SA (SA3)] and fertilizer type including without fertilizer (control), application of 50 kg ha−1 phosphorus (P), and application of wheat biochar (WB), cotton biochar (CB) and sesame biochar (SB) (2 % w/w). Under water stress, CB at SA0 and SA3 could improve the total chlorophyll by 119.4 and 70.6 %, compared to control, respectively. Also, carotenoid content in SA3 treatments increased in the range of 75.8 to 34.6 % compared to SA0. CB at SA3, increased catalase activity by 11.4 % compared to SB. At SA3, the highest RWC was observed in WB and CB by 26.7 and 18.1 % increases compared to SA0, respectively. At SA3, CB could enhance grain yield by 24.8 % under water stress. Under water stress, at SA3, remobilization efficiency from 63.2 % in control was enhanced to 69.2, 74.3 and 68.1 % in WB, CB and SB, respectively. CB and WB had better chemical properties in terms of EC, N, P, K and micronutrients compared to SB. These properties of BC and WB enhanced their ability to increase the nutrient availability, biochemical properties and consequently the grain yield enhancement, especially when applied with SA3.

Structure-property correlations study in biochar-enhanced polyamide composites for sustainable materials development

This study explores the synthesis and characterization of polyamide/biochar composites via in situ polymerization of 12-aminolauric acid with varying biochar concentrations. The motivation behind this research is to enhance the properties of polyamide 12 (PA12) by integrating biochar, a sustainable material derived from biomass, to improve both performance and environmental impact. A detailed structure-property correlation analysis was conducted to assess the effects of biochar on PA12's morphology, mechanical behavior, crystallinity, thermal stability, viscoelastic performance, and environmental sustainability. Key findings include successful PA12 synthesis, confirmed by FTIR and 1H NMR spectroscopy. Increased biochar content led to a decrease in molecular weight and an increase in crystallinity from 27 % to 38 %, suggesting enhanced nucleation effects. SEM analysis showed excellent dispersion and compatibility of biochar within the PA12 matrix, leading to significant improvements in tensile strength (from 38 ± 1 MPa to 54 ± 2 MPa) and modulus (from 745 ± 30 MPa to 2055 ± 65 MPa). Rheological tests demonstrated shear-thinning behavior, facilitating effective extrusion-based 3D printing of a complex object with 50 wt% biochar. A life cycle assessment revealed substantial environmental benefits, including a net reduction of 1.83 kg·CO₂ equiv.·kg⁻1 due to the use of biochar derived from wood pyrolysis. These findings highlight the potential of PA12/biochar composites as environmentally sustainable structural materials, combining enhanced functional properties with significant ecological advantages.

Effects of biochar on growth and yield of Wheat (Triticum aestivum L.) under salt stress

Globally from abiotic stresses, salt stress is the major stress that limits crop production. One of them is wheat that has been utilized by more than 1/3 of the world population as staple food due to its nutritive value. Biochar is an activated carbon that can ameliorate the negative impacts on plants under saline conditions. The present study was conducted to examine the ameliorative impact of “Biochar application” to Triticum aestivum L. plant grown under salinity stress and evaluated on the basis of various growth, yield, physiological, biochemical attributes. Preliminary experiment was done to select the Triticum aestivum L. varieties with 90% germination rate for further experiment. The selected varieties, FSD08 and PUNJAB-11 of wheat were treated with two levels of sodium chloride (0 mM and 120 mM). Two varieties of wheat included FSD08 and PUNJAB-11 were treated with two levels of sodium chloride (0 mM and 120 mM). To address the impact of salt stress two levels of biochar 0% and 5% was used as exogenous application. A three way completely randomized experimentation was done in 24 pots of two wheat varieties with three replicates. The results demonstrated that salt stress affected growth, physiological attributes, yield and inorganic mineral ions (Ca2+ and K+) in roots and shoots parameters of wheat negatively while biochar overall improved the performance of plant. SOD, CAT, APX and POD activities enhanced during salt stress as the plant self-defense mechanism against salinity to minimize the damaging effect. Salt stress also significantly increased the membrane permeability, and levels of H2O2, MDA, Cl and Na ions. Biochar treatment nullified negative impacts of NaCl and improved the plant growth and yield significantly. Hence, biochar amendment can be suggested as suitable supplement for sustainable crop production under salinization.

Impact of biochar on the degradation rates of three pesticides by vegetables and its effects on soil bacterial communities under greenhouse conditions

A 28 days pesticide degradation experiment was conducted for broccoli (Brassica oleracea L. var. italica Planch) and pakchoi (Brassica chinensis L.) with three pesticides (chlorantraniliprole (CAP), haloxyfop-etotyl (HPM), and indoxacarb (IXB)) to explore the effects of biochar on pesticide environmental fate and rhizosphere soil diversity. Rice straw biochar (RB) was applied to soil at a 25.00 t ha−1 dosage under greenhouse conditions, and its effects on the degradation of three pesticides in vegetables and in soil were investigated individually. Overall, RB application effectively facilitated CAP and HPM degradation in broccoli by 13.51–39.42% and in broccoli soil by 23.80–74.10%, respectively. RB application slowed the degradation of CAP, HPM and IXB in pakchoi by 0.00–57.17% and slowed the degradation of CAP in pakchoi by 37.32–43.40%. The results showed that the effect of RB application on pesticide degradation in crops and soil was related to biochar properties, pesticide solubility, plant growth status, and soil characteristics. Rhizosphere soil microorganisms were also investigated, and the results showed that biochar application may be valuable for altering bacterial richness and diversity. The effect of biochar application on pesticide residues in crops and soil was influenced by the vegetable variety first, and the second was pesticide characteristics. RB applied to soil at a 25.00 t ha−1 dosage under greenhouse conditions is recommended for broccoli production to ensure food safety. Our results suggested that biochar application in soil could reduce pesticide non-point source pollution, especially for highly soluble pesticides, and could affect soil microorganisms.

Effect of Biochar Amendment and Organic Fertilization on the Yield and Nutritional Quality of Artichoke (Cynara cardunculus L.)

Organic fertilization is gaining importance as an alternative to chemical fertilization. However, the effects of organic products on crop quality need to be characterized, especially in biochar and derived products. Therefore, the effect of enriched biochar supplied with an organic fertilizer (biochar) on the yield and nutritional compounds of artichoke (Cynara cardunculus var. Scolymus) heads was analyzed and compared to inorganic conventional fertilization (control). For this purpose, the number of fruits and their weights were determined, along with the nutritional properties of artichoke heads, such as mineral content, fatty acids, phenolic compounds, and flavonoids. The results showed that biochar increased crop yield, as registered by the higher number of marketable or commercial artichokes compared to the control. Additionally, biochar-treated plants exhibited significantly higher contents of Ca, Mg, and S in the artichoke heads, but they had a decreased content of Co, Cu, and Zn. The fatty acid content in the biochar-treated artichokes was also significantly higher, primarily due to the presence of palmitic acid. Conversely, the contents of phenolic compounds (e.g., flavonoids) were negatively and significantly affected by the application of biochar. In conclusion, the application of biochar as a soil amendment in combination with organic matter for growing artichokes in the semiarid Mediterranean area (e.g., Murcia Region) favored an increase in yield without compromising its nutritional composition. Further developments to establish protocols for the extended use of biochar in this agri-food production area are guaranteed.

Ball milling nano-sized biochar: bibliometrics, preparation, and environmental application.

Nano-sized biochar, which is a small structure prepared from biochar by grinding, has surpassed traditional biochar in performance, showing enhanced effects and potential for a wide range of environmental applications. Firstly, this paper visualizes and analyzes the literature in this field by CiteSpace to clarify the development trend of nano-sized biochar. The review intuitively shows the most influential countries, the most productive institutions, and the most concerned hot spots in the field of nano-sized biochar. Secondly, these hotspots in environment management are summarized by keywords and clustering: (1) The application of ball milling is a modification scheme that researchers have paid attention to, and it is also a key method for preparing biochar nanomaterials. It has a more dispersed structure and can support more modified materials. (2) Nano-sized biochar in the comprehensive utilization of water, soil, and plants was discussed and is a small range of application modification methods. (3) The bidirectional effects of nano-sized biochar on plants were analyzed, and the challenges in its application were listed. Finally, the economic management of nano-sized biochar and the relationship between microorganisms are the focus of the next research.

Priming effect of pigeon pea and wood biochar on carbon mineralization of native soil organic carbon and applied municipal solid waste compost

A laboratory incubation experiment was conducted for 36 days to study the effect of pigeon pea biochar (PPB) and wood biochar (WB) on carbon mineralization of native soil organic carbon (SOC) and municipal solid waste compost (MSWC) applied to soil. The MSWC addition enhanced soil respiration by 2-fold (231 mg C kg-1 soil) over the control (118 mg C kg-1 soil). The PPB addition significantly (P &lt; 0.05) increased cumulative loss of carbon as CO2, whereas WB significantly decreased the cumulative loss of C over control. Addition of PPB at 5% and 10% levels increased SOC mineralization (positive priming) +22.9% and +31.2%, respectively; whereas reduction in SOC mineralization (negative priming) was noticed in WB (5% and 10%) treated soils by -3.1% and -21.7%, respectively. Similarly, WB induced strong negative priming effects (-21.9% and -29.5%), while PPB caused a weak positive priming effect (+3.0% and +11.6%) at 5% and 10% levels on mineralization of added labile carbon substrate (MSWC), respectively. Results indicate the hardwood (Prosopis juliflora) biochar exhibits refractory properties that inhibit mineralization of both native SOC and applied organic compost (MSWC), and thereby it can be used as an amendment to stabilize native and applied organic matter in soil, which may significantly contribute to soil carbon sequestration.

Wetland plant species and biochar amendments lead to variable salinity reduction in roadway-associated soils

Salinization is an emerging threat in freshwater wetlands, with few techniques available to mitigate anthropogenic inputs such as road salts. Phytoremediation and biochar addition have each been proposed to remediate salt-affected soils generally, but interactive effects in wetland environments to improve soil conditions adjacent to roadways are not well understood. We conducted an 88-day fully factorial greenhouse experiment to quantify the effects of three plant treatments (unvegetated, Typha × glauca and Phragmites australis) and three biochar rates (0.0, 2.5, 5.0 % wt/wt) on the soil and leachate of a simulated wetland system. Both plant species significantly reduced soil Cl− content relative to unvegetated controls, while Typha also significantly reduced Cl− content of leachate and soil Na+. The difference in effects was likely due to different salt tolerance strategies: the salt-accumulating Typha contained a significantly higher volume of Na+, Cl−, and water in its tissue than Phragmites, whose greater K+:Na+ ratio and similar soil Na+ to controls indicated a salt exclusion strategy. Biochar did not influence the growth of either species but moderately increased tissue Na+ concentration in Typha. Furthermore, biochar's effects on soil and leachate salt levels varied by application rate with the medium rate moderately increasing soil Na+ and Cl− and leachate Cl−, while the highest application did not differ from controls across all metrics. Our results suggest that phytoremediation can be optimized with salt-accumulating species, whose mechanisms of salt tolerance involve the accumulation of salt ions from the surrounding environment. The consistent flooding in our study may have inhibited the influence of biochar. We recommend future studies parse the effects of water levels and redox potential on biochar's ability to influence wetland salinity.Data repository: doi.org/10.17605/OSF.IO/9QFZ7

Pyrolysed maize feedstock utilization in combination with Trichoderma viride against Macrophomina phaseolina

Maize cultivation is under the growing threat of charcoal rot (Macrophomina phaseolina). Chemical control of diseases imparts serious health hazards to humans and the ecosystem. Biochar as an alternative disease management approach has been under consideration of the researchers for some time now. The biochar utilized in this study was derived from maize stalks and cobs. Crystallographic structure, inorganic minerals content and size of maize biochar were analyzed by powder X-ray diffractometer, while scanning electron microscopy revealed rough, irregular, tubular structure of the biochar surface. EDX spectra revealed that the maize biochar composition was dominated by ‘C’ followed by ‘O’. The current study was designed to determine the synergistic effect of maize biochar (MB), and biocontrol agent (BCA) Trichoderma viride as soil amendments on the suppression of M. phaseolina. In vitro bioassays were conducted to check the efficiency of antagonistic effect of Trichoderma spp., in combination with maize biochar. On the basis of maximum mycelial growth inhibition T. viride was selected for a glasshouse experiment. Maize plants were grown in pots containing a mixture of soil with MB at application at the rate of 3 and 6% (v/v) separately, associated with or without T. viride. Treatments amended with 3% MB inoculated with M. phaseolina significantly reduced the percentage disease severity index by 40%. While in the presence of T. viride, 3% MB showed maximum disease suppression and a minimum percentage severity index i.e. 60 and 20%, respectively. Highest nitrogen contents were 18.4 g kg−1 observed in treatment 6% MB, while highest phosphorus and potassium contents were 3.11 and 15.2 g kg−1, respectively in the treatment with 3% MB. Conclusively, the effect of variable concentrations of maize biochar and T. viride as soil amendment was evident on the development of charcoal rot, growth and physiology of maize plants. According to the available literature, our report is the first on the implementation of biochar in synergism with T. viride to suppress the charcoal rot in maize.

Short-Term Effect of the Combined Application of Rice Husk Biochar and Organic and Inorganic Fertilizers on Radish Growth and Nitrogen Use Efficiency.

Research on soil biochar fertilization has mainly been conducted on cereal crops, and information on its potential for radish production remains inconsistent. Therefore, a pot experiment was conducted to examine the short-term effects of rice husk biochar on radish growth and nitrogen use efficiency (NUE). An investigation was conducted with two application rates of biochar alone, (10 t ha-1 (B10) and 25 t ha-1 (B25), and biochar + chicken manure application with and without NPK fertilizer. The results indicated that the application of biochar 25 t ha-1 + chicken manure (B25:CHM) and the combination of biochar 25 t ha-1 + chicken manure + NPK fertilizer (B25:CHM:NPK) significantly increased root yield by improving NUE, fertilizer recovery efficiency (REN), agronomic efficiency (AE), nitrogen harvest index (NHI), and retaining soil NH4+-N. Although biochar application alone did not significantly influence radish growth on a short-term basis, B10 and B25 increased root yields by 10% and 20%, respectively, compared with the control. Notably, the role of biochar application when combined with organic and inorganic fertilizers was to retain fertilizer N and promote N uptake efficiency by radishes, as higher rates of biochar resulted in higher NUE. Our results suggest that B25:CHM is a suitable combination for organic farming.

Biochar Amendment in Green Roof Substrate: A Comprehensive Review of the Benefits, Performance, and Challenges

Green roofs (GRs) are a well-established green infrastructure (GI) strategy that have been extensively studied for decades to address a growing array of social and environmental challenges. Research efforts have been continuously made to contribute to the awareness of benefits of GRs and towards their widespread application. The substrate, which is one of the crucial layers of a GR system, plays a major role in the serviceability of GRs. Thus, several studies have been undertaken to alter the substrate characteristics by applying innovative substrate additives. Biochar, a carbon-rich material with a highly porous structure and large specific surface area, has been found advantageous in several areas such as agriculture, water filtration, environmental remediation, construction, and so on. However, the application of biochar in GRs has been insufficiently studied, partially because biochar amendment in GRs is a relatively recent innovation. Furthermore, a comprehensive review of the performance of biochar-amended GR substrates is lacking. This review paper aims to summarize the past performance of GRs enhanced with biochar by considering the various benefits that biochar offers. The results indicate that most of the reviewed studies observed increased retention of runoff and nutrients when utilizing biochar. Additionally, the capabilities of biochar in improving thermal insulation, plant performance, and microbial diversity, as well as its effectiveness in sequestrating carbon and controlling soil erosion, were mostly agreed upon. Notwithstanding, a definitive conclusion cannot yet be confidently made due to the limited research information from biochar–GR systems and the uneven research focus observed in the studies reviewed. The influence of biochar-related variables (including amendment rates, application methods, processed forms, and particle size) on the effectiveness of biochar was also discussed. Opportunities for future research were suggested to fill the research gaps and address challenges restricting the application of biochar in GRs. Detailed information from past research findings could serve as a foundation for further investigations into the large-scale implementation of biochar in GRs.

Residual Effects of Rice Husk Biochar and Organic Manure Application after 1 Year on Soil Chemical Properties, Rice Yield, and Greenhouse Gas Emissions from Paddy Soils

Biochar is stable in soil and can have long-term effects on its physicochemical properties. Hence, a pot experiment was conducted with medium-fertility (MF) and low-fertility (LF) soils after 1 year of rice husk biochar and organic fertilizer application to determine biochar’s residual effects on soil chemical properties, grain yield, and greenhouse gas emissions. In previous years, biochar alone (at application rates of 5 and 10 t ha−1) and biochar combined with chicken manure (CHM) or cow manure (at application rate of 5 t ha−1) were applied to the soil. In the present year, the soils were fertilized with only chemical fertilizers. Results indicated that application of 10 t ha−1 biochar combined with 5 t ha−1 CHM (B10:CHM) produced the highest grain yield and total global warming potential (GWPtotal) in both soils. Regarding grain yield, non-significant results were detected for B10:CHM, B5:CHM, and B10. This study revealed that biochar retains nutrients without annual reapplication and has long-term effects. Although biochar application can suppress N2O emissions effectively, the combined application of biochar 10 t ha−1 and organic manure significantly increased CH4 emissions. Overall, B5:CHM can be recommended for rice cultivation since it improves grain yield without increasing GWPtotal.

Polyvinyl chloride nanoplastics transport inhibited in natural sandy soil by iron-modified biochar.

The small particle size of nanoplastics allows them to migrate through soil and make them highly bioavailable, posing a potential threat to groundwater. Measures are urgently needed to reduce the migration of nanoplastics in soil. However, there is limited research available on this topic. In this study, two types of iron-modified biochar (magnetic corncob biochar (MCCBC) and magnetic walnut shell biochar (MWSBC)) were selected and their effects on the transport of polyvinyl chloride nanoplastics (PVC-NPs) in natural sandy soil columns under different ionic types and strengths were investigated. The results show that the transport of PVC-NPs in single sandy soil columns was rapid and efficient, with the estimated breakthrough rate of 85.10%. However, the presence of MCCBC and MWSBC (0.5%, w/w) significantly inhibited the transport of PVC-NPs in sandy soil columns (p < 0.05), and MCCBC had a stronger inhibitory effect on the transport of PVC-NPs than MWSBC. This can be attributed to the fact that the adsorption of PVC-NPs on adsorbents followed the order as: MCCBC > MWSBC > sandy soil. The retention of PVC-NPs by MCCBC and MWSBC is determined by ionic type and ionic strength. The presence of coexisting ions enhanced the inhibitory effect of iron-modified biochar on the transport of PVC-NPs, with the following order: Ca2+ > SO2- 4 > Cl- > NO- 3. The inhibitory effect of MCCBC and MWSBC on the transport of PVC-NPs in soil columns increased with increasing ionic strengths. Furthermore, MCCBC and MWSBC inhibited the migration of PVC-NPs in a rainwater-soil system. The mechanisms by which MCCBC and MWSBC affect the transport of PVC-NPs in soil columns were considered to enhancing adsorption and decreasing soil pore volume. The results provide new insights into the management of soil nanoplastic pollution.

Residual effect of biochar on microbial biomass and enzyme activities of soil cultivated with grape varieties: a two -year field assessment

Biochar has received increasing attention as a soil conditioner, being known for its ability to confer numerous benefits to the soil. Derived from the thermal decomposition of organic materials under low levels of oxygen, biochar concentrates essential nutrients and carbon while having low carbon dioxide emissions. Our hypothesis is that biochar applied as a top dressing can improve soil microbial attributes even after two years in a soil cultivated with different grape varieties. To test this hypothesis, we conducted a field experiment using different doses of cashew wood biochar applied to two grape varieties and evaluated its residual effect on microbial biomass and soil enzymatic activities. The design used was a randomized block design, in a 4 x 2 factorial scheme, with five replications: four doses of biochar (0, 5, 10 and 15 ton ha-1) and two grape varieties (Cabernet sauvignon and Malbec). Soil collection was carried out at a depth of 0-20 cm, to evaluate total organic carbon, microbial biomass carbon and soil enzymatic activities. Our findings revealed that the effect of grape varieties on soil biological properties was more pronounced than the biochar dose, indicating that there is a small residual effect of biochar doses after 2 years of application. Overall, our study provides important insights into the residual effect of biochar on soil microbial attributes and is considered an ecologically sustainable alternative, as it solves the problem of waste reuse and provides a disposal that brings benefits to soil properties.

Effects of straw biochar on microbial-derived carbon: A global meta-analysis

Pyrolyzing biomass (e.g., crop straw) to produce biochar is a sustainable strategy in agricultural farmlands. Straw-derived biochar could increase soil organic carbon (SOC) and microbial-derived carbon (C) compared to no addition, while it is imperative to understand the effects of straw-derived biochar compared to its feedstock (e.g., straw). We retrieved 321 and 387 observations to investigate the effects of straw-derived biochar on microbial-derived C (e.g., microbial biomass C (MBC) and microbial necromass C (MNC)) taking no addition and straw as control, respectively. Notably, straw-derived biochar significantly increased dissolved organic C (DOC) by 24.9% and provided available substrates for microbial utilization, thus improving MBC by 16.7% and MNC by 19.7% compared to no addition. Nevertheless, compared to its feedstock (crop straw), straw-derived biochar significantly decreased MBC by 26.1% and MNC by 18.0% attributed to lower DOC, supported by a positive correlation between MBC and DOC (R2 = 0.53). A negative correlation between changes in MBC and SOC indicated the adverse of microbial activity for C accrual under conversion from straw to biochar. Moreover, soil layer, experiment duration, and initial C/N ratio are the crucial factors affecting MBC under the conversion from straw to biochar. Specifically, with significant variations among subgroups, when compared to straw addition, straw-derived biochar had lower reduction in MBC observed on 0–5 cm layers, mean annual precipitation ≥550 mm, mean annual temperature ≥10 °C, clay loam soil, experiment duration≥1 yr, initial SOC≥14 g kg−1, pH≥8, and bulk density ≥1.28 g cm−3. Straw-derived biochar even increased MBC by 32.8% in an anaerobic environment, associated with biochar produced under limited oxygen and anaerobic microorganisms dominating the microbial community. This study concludes that the conversion from crop straw to biochar increases SOC but constrains microbial-derived C, which may disturb the microbial-mediated C-cycling process.

Sustainable soil health and agricultural productivity with biochar-based indigenous organic fertilizers in acidic soils: insights from Northwestern Highlands of Ethiopia

Depletion of soil fertility in tropical regions is a pressing concern contributing to lower crop yields. This study aimed to evaluate the effects of biochar and co-composted biochar on acidic soil and the growth performance of teff (Eragrotis teff (Zucc.)) in the sub-tropical highlands of Ethiopia. Co-composted biochar was produced by mixing Acacia decurrens biochar with chicken litter and cow dung manure at different ratios of 100:0:0, 25:75:0, 15:85:0, and 25:0:75. Treatment impact on soil properties and crop yields were evaluated with applications of 0, 5, 10, and 20 t ha–1 in field trials. The study shows interaction effects of biochar-based amendments significantly (P < 0.001) improved soil bulk density (g/cm3), moisture content (%), pH, total nitrogen (%), total organic carbon (%), available phosphorus (mg/kg), cation exchange capacity (cmol ( +)/kg)) and teff yield. The application of 20 t ha–1 sole biochar significantly improved soil acidity by 0.99 units. Soil treated with 20 t ha–1 of BCLL and BCM resulted in notable increases in soil pH, ranging from 0.12 to 0.83 units for BCLL and 0.15 to 0.81 units for BCM. Soil treated with 20 t ha–1 BCLL showed a significant increase in tef grain yield, with improvements of 315%, 48%, 48%, and 84% compared to the control, compost, inorganic fertilizer, and sole biochar application, respectively. In conclusion, the application of 20 t ha–1 BCLL has significantly improved soil properties and crop yield. This emphasizes the need to expand the intervention to assist farmers facing similar soil fertility challenges.

Converse Responses of Biochar Application on N2O Emissions in Soils at Different pH Values in a Subtropical Citrus Orchard

The aim of this study was to explore the effect of biochar on N2O emissions in soils with different pH levels. Soils with five pH levels (4.0, 5.1, 5.8, 6.6, and 7.2) were incubated in two conditions, with 0% biochar (CK) and 1% biochar (BC), for 23 days. N2O emissions were measured at nine time points, and soil chemical properties, AOA-amoA, AOB-amoA, nirK, nirS, and nosZ, were analyzed. Partial least squares path modelling (PLS-PM) was used to assess the effect of nitrification and denitrification pathways on potential N2O emissions. The results showed that biochar reduced N2O emissions in highly acidic soil (pH 4.0) but increased emissions in soils with pH values ranging from 5.1 to 7.2. In highly acidic soils, decreased N2O emission was associated with increased soil pH (p &lt; 0.05) and decreased dissolved organic carbon content (p &lt; 0.05), leading to higher nosZ gene abundance (p &lt; 0.05). Meanwhile, in acidic to neutral soils, biochar application increased soil pH (6.6–11.7%), dissolved organic nitrogen (5.9–29.5%), dissolved organic carbon (8.6–41.0%), stimulated AOB-amoA, nirK, nirS gene abundance (p &lt; 0.05), and thus increased N2O emissions. The results verified the influence of nitrification and denitrification genes on N2O production in soils with different pH values. In conclusion, biochar had different effects on N2O emissions based on soil pH, highlighting the need to consider pH when using biochar to mitigate N2O emissions in subtropical citrus orchards.