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A large amount of agricultural waste is produced annually in China, and these agricultural wastes include crop residues and the manure generated from poultry and livestock farming. But there is still a considerable portion of agricultural waste that is not recycled and disposed of or directly burned. Therefore, if these agricultural wastes can be reasonably utilized, it will generate significant socio-economic and environmental benefits. Soil salinization has become one of the main threats to soil health, and agricultural waste is considered an effective tool for improving saline alkali land due to its unique properties. Utilizing agricultural waste to improve saline alkali land has advantages such as wide material sources, low cost, and low environmental risks. This article reviews the effectiveness and potential physical, chemical, and biological mechanisms of agricultural waste in improving soil health in saline alkali soils. Agricultural waste is mainly used to improve saline alkali land through a direct return to the field, burial of salt barriers, pyrolysis and carbonization into biochar, and composting, which can play a positive role in physical, chemical, and biological aspects. Finally, the problems existing in the improvement of saline alkali land with agricultural waste were discussed, and future research directions and hotspots in this field were proposed. It is believed that the improvement of ecological service functions is the key to its sustainability. This article can provide a theoretical basis for the study of agricultural waste in the improvement of saline alkali land, and help to further explore the resource utilization pathways of agricultural waste in sustainable agriculture. [ABSTRACT FROM AUTHOR]

Long term tillage in mollisol of Northeast China has led to an inhomogeneous distribution of soil organic matter content. Biochar, a carbon material, changes the soil carbon pool and physical-chemical characteristics after adding to the soil. However, the mechanism remains unclear for the relation between the soil organic matter level and biochar amount. So, the soil physical and chemical properties and soybean growth in a two-year pot experiment were detected at three levels of soil organic matter and three biochar additions (0, 1% and 10%). The difference was found in two biochar application rates. The 1% biochar addition had no positive effect on the soil chemical properties based the two-year experiment. However, 10% biochar application significantly increased the soil water content (8.0%-39.7%), the total porosity (9.7%-21.3%), pH (0.26-0.84 unit), organic matter content (89.0%-261.2%), and the available potassium content (29.0%-109.1%). The biomass of soybean increased by 19.4%-78.1% after biochar addition, yet, the soil bulk density reduced at the range of 12.6%-26.0% by 10% biochar addition. Only the 100-grain weight was correlated to the interaction of biochar and the native soil organic matter. All the indicators showed that the interaction between biochar and soil organic matter level was weak in mollisol. The effects of biochar on the physical-chemical properties relied on its amount. When biochar is applied to the soil, the amount of biochar should be considered rather than the native soil organic matter level. [ABSTRACT FROM AUTHOR]

The Qinghai-Tibet Plateau is an important ecological security barrier in China. Considering the rich local waste biomass with a single treatment method and low level of resource utilization, biochar utilization of solid waste biomass can be carried out based on the research that biochar has abundant material sources. According to the application methods of various types of solid waste resources that have not been carried out, this review analyzes and discusses various types of waste biomass resources in the plateau region, such as sewage plant sludge, food waste, green leaves, barley straw, yak manure, and the unique Tibetan tea and Tibetan medicine residue waste, and reviews the biochar methods and applications for similar raw materials at home and abroad. Further, the technical outlook of solar pyrolysis technology and UV radiation modification technology and the development of hybrid pyrolysis to enhance the performance of biochar materials and heavy metal passivation are proposed by utilizing the solar energy resources of the Tibetan Plateau. Collectively, it provides a reference for prevention and restoration methods for the fragile ecological environment of the Qinghai-Tibet Plateau, reduces the pressure of waste disposal in the region, and realizes the resource utilization of waste. [ABSTRACT FROM AUTHOR]

With the development and modernization of rural economies, the integration of agriculture, cultural tourism, and other fields has gradually become a new driving force for promoting rural revitalization. However, in recent years, the development of mines and the utilization of resources have led to severe heavy metal pollution of farmland soil, causing significant food safety risks and economic losses, which pose serious challenges to the integration of agriculture, culture, and tourism. Therefore, China has invested a lot of attention in addressing the issue of soil remediation in abandoned rural mining areas. The study focuses on an abandoned mining area polluted by heavy metals such as Cd, Zn, and Cu in a certain area. Two materials, biochar and compost, were added to the soil in the polluted area, and the weight ratios of biochar and compost were set to 0:100, 10:90, 20:80, 40:60, 60:40, and 100:0. A new type of biochar was prepared by mixing two materials at high temperatures, and its effects on the pH and organic carbon content of soil in heavy metal polluted rural abandoned mining areas were explored. The effective removal and adsorption of heavy metals in the soil were also investigated, as was the promotion of crop growth in the soil area. This indicates that the use of biochar and compost can significantly repair heavy metal contaminated soil in mining areas and improve soil availability. Meanwhile, research has found that the integration of agriculture, culture, and tourism provides a unique perspective on soil remediation technology, which may involve maintaining rural cultural traditions, enhancing the attractiveness of rural tourism, and ensuring food safety and agricultural sustainability. Therefore, the selection and implementation of repair technologies need to consider multiple factors to ensure the triple benefits to the economy, society, and environment. [ABSTRACT FROM AUTHOR]

Sorption is the most important process influencing the amount of herbicide retained in soils. The special properties of biochar could influence the soil retention of pollutants through adsorption. However, the detailed sorption mechanisms as influenced before and after applying biochar to soils with different properties are unclear. This study examined the sorption characteristics of metolachlor using soil samples collected from South China. Sorption experiments were conducted using a batch equilibration method. After comparing the metolachlor sorption constants observed for all soil samples, our results showed that the application of biochar significantly increased the capacity of metolachlor adsorption. Without biochar, sorption capacity (Kf) was positively related to soil organic matter and to a soil particle size of 0.002–0.02 mm in soils developed from granite, of 0.002–0.02 mm in soils developed from delta shockwaves, and of 0.002–0.02 mm, together with complex iron oxide and total iron content, in soils developed from arenaceous shale. Moreover, sorption capacity (Kf) with biochar was positively related to peroxidase in soils developed from granite and to dissociative iron oxide and total iron content in soils developed from arenaceous shale. Our results show that biochar greatly affects metolachlor sorption behavior, probably because of qualitative differences in the structural characteristics of soils with different developmental parent materials and properties. [ABSTRACT FROM AUTHOR]

Biochar application to soil is widely recognized as a promising agricultural management practice to increase crop production by enhancing the physical, chemical, and microbiological properties of the soil. Despite the fact that numerous studies have investigated biochar production and alterations in soil properties, the effects of biochar on contrasting soils within the same region remain poorly understood, especially for semi-arid regions. Therefore, a three-year field experiment was initiated in 2020 wherein biochar was applied once to a buckwheat field at rates of 0, 20, 40, and 60 Mg ha−1 (BC0: no biochar; BC1: 20 Mg ha−1; BC2: 40 Mg ha−1; BC3: 60 Mg ha−1) for two soil types (aeolian sandy and grey meadow soil) in the northeast of Inner Mongolia, China. The soil water storage (SWS), nutrient contents (organic matter, available nitrogen, phosphorus, and potassium), microbial biomass (carbon, nitrogen, and phosphorus), and enzyme activities (urease, invertase, and alkaline phosphatase) were assessed at a soil depth of 0–15 cm as part of the soil quality assessment, and the buckwheat grain yield was estimated for crop productivity evaluation. The results showed that biochar amendment improved selected soil physicochemical and microbiological properties and buckwheat yields for both soil types. Compared to BC0, the biochar addition increased buckwheat yields, on average, by 11.23% to 22.82% in aeolian sandy soil and by 7.36% to 14.87% in grey meadow soil across three years. The results of principal component analysis (PCA) and random forest analysis (RFA) indicate that soil available nutrients and microbiological properties were the most important factors influencing buckwheat yields in aeolian sandy soil and grey meadow soil, respectively. Based on RFA, the available potassium, phosphorus, and nitrogen were found to contribute at rates of 13.10%, 10.06%, and 8.12%, respectively, to buckwheat yields in aeolian sandy soil. In contrast, alkaline phosphatase, urease, and microbial biomass carbon contribute 20.26%, 8.48%, and 7.82%, respectively, to the buckwheat yields in grey meadow soil. Following biochar addition, there was greater improvement in soil health and buckwheat production for aeolian sandy soil than grey meadow soil. In conclusion, biochar addition is an effective practice for improving soil health and crop productivity in both aeolian sandy soil and grey meadow soil in semi-arid regions. [ABSTRACT FROM AUTHOR]

Apples are not only a foodstuff, but also a raw material for many industrial production fields, and the market demand is constantly increasing. The Loess Plateau is one of the world's largest apple-producing areas, with about 85% are aged orchards (more than 20 years old), facing problems such as poor soil water retention, degradation of tree strength, and declining yield and quality, etc., so do aged orchards in other regions of the world, and study on improving quality and increasing yield of aged orchards is of great significance to the sustainable development of the apple industry. Here, 6 treatments (2, 4, 6, 8, 10 and 12 kg/plant) were designed in the experiment to study the effects of biochar on yield and quality in aged apple orchards. The study showed that: biochar could improve soil water retention, but caused the soil alkalization; biochar could improve apple quality and increase yield, T3 and T4 were of better quality, and T3 had the highest yield. Comprehensive analysis, T3 is the optimal scheme. The results not only provide a reference for aged orchards worldwide, but also have great significance for the sustainable development of the apple industry. [ABSTRACT FROM AUTHOR]

The Hetao irrigation region is located in Inner Mongolia, China, within a dry and semi-dry region. This region suffers from poor agricultural productivity and environmental damage due to the presence of saline soil. To explore the growth of salty lands using a more environmentally friendly method, this research employed three eco-conscious amendments to improve the soil. These include flue gas desulfurization gypsum (S), humic acid (H), and biochar (C). During a two-year study, the amendments were utilized to enhance the soil quality for planting sunflowers. Humic acid was used prior to every seedling season, whereas the remaining two substances were only used once. These additions increased the soil's water-holding capacity, reduced soil salinity during sunflower growth, and improved the macroaggregate proportion. The most effective treatment for decreasing the soil's salt content after the seedling stage was the application of humic acid (0.6 t ha−1). Biochar (15 t ha−1) decreased the soil's bulk density (from 1.49 to 1.34 g cm−3) and mostly increased the sunflower seed yield up to 3133−3964 kg ha−1. Humic acid addition significantly increased the aggregate (>0.25 mm) content up to 27.88% after the experiment, but it led to a lower seed yield (2607−3686 kg ha−1). In 2019, the temperature was lower compared to 2018, which may have led to a reduction in the yield. However, these three amendments could potentially increase yields by more than conventional methods. These three environmentally friendly amendments are useful for improving saline soil and increasing yields. More studies are required to understand their impacts on larger areas and over extended periods. [ABSTRACT FROM AUTHOR]

Purpose: Excessive application of nitrogen fertilizers on farmland widely occurs in China, which has been recognized as one of the main sources of non-point pollution. To reduce the nitrogen loss in agricultural soils, some specific biochar can be introduced to increase the water-holding capacity of soils and to reserve soil nutrition. The effects and mechanisms of biochar application on decreasing nutrient losses after fertilization were systematically evaluated and understood through both pot and field experiments. Materials and methods: This study was objected to investigate the effects of neutral biochar (NBC, pH 6.6–7.1) and its combination with urease inhibitor (UI) on nitrogen mitigation and reservation in farmland soil, and the interactions among the mixed soils (biochar, nitrogen fertilizer, and soil) under both pot and field experiments. Results and discussion: The application of straw biochar could reduce the amount of ammonia volatilization in soil. The maximum inhibition of ammonia volatilization loss accounted for 27.67% of fertilizer applications. In field experiments, neutral biochar could reduce the leaching of soil NH4+-N and NO3—-N, and this effect was more evident for NO3—-N (68 mg/kg) compared to no fertilization in the soil layer 20–40 cm. With the addition of neutral biochar and urease inhibitors, the content of soil total nitrogen increased greatly with 1.70 g/kg. Conclusion: Neutral biochar from waste agricultural straw and commercial urease inhibitors were applied for nitrogen reservation in pot and field experiments. The application of neutral biochar played a positive role in lower volatile ammonia loss and higher nitrate content compared to urease inhibitor application only. These findings reveal the potential of neutral biochar for the improvement of agricultural soil. [ABSTRACT FROM AUTHOR]

While many studies have examined the role of biochar in carbon (C) accrual in short-term scale, few have explored the decadal scale influences of biochar on non-biochar C, e.g., native soil organic C (SOC) and added substrate. To address this knowledge gap, soils were collected from decade-old biochar field trials located in the United Kingdom (Cambisol) and China (Fluvisol), with each site having had three application rates (25–30, 50–60 and 75–100 Mg ha−1) of biochar plus an unamended Control, applied once in 2009. We assessed physicochemical and microbial properties associated with sucrose (representing the rhizodeposits) mineralization and the priming effect (PE) on native SOC. Here, we showed both soils amended with biochar at the middle application rate (50 Mg ha−1 biochar in Cambisol and 60 Mg ha−1 biochar in Fluvisol) resulted in greater substrate mineralization. The enhanced accessibility and availability of sucrose to microorganisms, particularly fast-growing bacterial genera like Arenimonas, Spingomonas, and Paenibacillus (r-strategists belonging to the Proteobacteria and Firmicutes phyla, respectively), can be attributed to the improved physicochemical properties of the soil, including pH, porosity, and pore connectivity, as revealed by synchrotron-based micro-CT. Random forest analysis also confirmed the contribution of the microbial diversity and physical properties such as porosity on sucrose mineralization. Biochar at the middle application rate, however, resulted in the lowest PE (0.3 and 0.4 mg of CO2-C g soil−1 in Cambisol and Fluvisol, respectively) after 53 days of incubation. This result might be associated with the fact that the biochar promoted large aggregates formation, which enclosed native SOC in soil macro-aggregates (2–0.25 mm). Our study revealed a diverging pattern between substrate mineralization and SOC priming linked to the biochar application rate. This suggests distinct mechanisms, biophysical and physicochemical, driving the mineralization of non-biochar carbon in a field where biochar was applied a decade before. Highlights: The application of biochar at a moderate rate (50–60 Mg ha−1) resulted in increased labile C mineralization and decreased priming of native SOC. Biochar amendments led to the reconfiguration of physicochemical properties, including pH, porosity, and the formation of aggregates. Modified microbial community structure towards more r-strategists caused greater sucrose mineralization. Biochar incorporation rate governed the C dynamics via (biophysical vs physicochemical mechanisms) in long-term biochar amended fields. [ABSTRACT FROM AUTHOR]

Film mulching and biochar have been applied as effective measures for increasing crop yields in arid and semi‐arid areas for many years. However, the effects of the temporal and spatial distributions of soil hydrothermal properties on crop yields are still unclear under film mulching and biochar addition. Thus, we conducted a field experiment with winter wheat on the Loess Plateau of China for two years (2020–2022) with three treatments: control, film mulching, and biochar. The results demonstrated that film mulching and biochar addition increased the average soil temperature in the 0–50 cm soil depth throughout the whole growth period and the influence depth exceeded 50 cm. Biochar addition only significantly increased soil temperature in the overwintering stage (p < 0.05). Film mulching increased the maximum and minimum temperatures in the 0–50 cm soil depth at seedling stage. Film mulching and biochar increased average ≥10°C accumulated soil temperature by increasing the ≥10°C accumulated soil temperature in the daytime and nighttime, and the number of days with a daily soil temperature ≥10°C during the whole growth period. Film mulching improved soil water storage in the 0–300 cm soil depth in each growth stage during both years, and also increased the wheat grain yield, aboveground biomass, and water use efficiency. Biochar addition increased the wheat grain yield and aboveground biomass of two years compared with control, but the increases were not significant (p > 0.05). In addition, correlation analysis showed that adequate temperatures in the 0–50 cm soil depth during the seedling and overwintering stages, and suitable soil moisture conditions in the 0–300 cm soil depth before sowing, jointing, and filling stages were important factors for increasing wheat grain yields under film mulching. In summary, film mulching mainly regulated the soil temperature in the 0–50 cm soil depth and moisture conditions in the 0–300 cm soil depth during different growth stages to increase grain yields. Film mulching has more obvious effects on moisture regulation, temperature regulation, and yield increases than biochar addition. Some environmentally friendly measures (such as conservation agriculture) with the same yield improving effect as mulching are also recommended to explore and promote in theLoess Plateau region. [ABSTRACT FROM AUTHOR]

Vegetable production in Subtropical China is distinguished by excessive nitrogen (N) fertilization, frequent irrigation, and multiple crop rotations in a single year. The aforementioned variables are closely related to soil nitrous oxide (N2O) and methane (CH4) emissions. Hence, we conducted a field trial to measure N2O and CH4 emissions using static chamber–gas chromatograph. Four treatments were used: control (CK) with no fertilizer, 100% chemical N fertilization (CN), the conventional 30% chicken manure N plus 70%CN (CMN + CN), and 30% chicken manure biochar N plus 70%CN (CMBN + CN). The annual cumulative N2O emissions reached 12.4, 63.5, 111.8, and 44.1 kg N2O-N ha−1 for the CK, CN, CMN + CN, and CMBN + CN treatments, respectively. Compared to the CN and CMN + CN treatments, the CMBN + CN treatment reduced N2O emissions by 35.9%–65.7%, while it simultaneously increased the total vegetable yield by 16.1% compared to the CN treatment. Seven seasons mean N2O emission factors are 1.3% for CN, 3.8% for CMN + CN, and 0.9% for CMBN + CN. The CH4 emission was negligible, ranging from 0.07 kg CH4-C ha−1 for the CK treatment to 0.8 kg CH4-C ha−1 for the CN treatment. N2O emissions peaked under the conditions of an interior chamber temperature of around 31.9 °C and the water-filled pore space (WFPS) of the soil being approximately 60%. Future climate change will intensify, triggering higher N2O emissions from subtropical vegetable fields. CMB can be one of the best substitutes for direct chicken manure application as a soil supplement because it has a beneficial effect on improving vegetable yield and reducing N2O emissions in Subtropical China. [ABSTRACT FROM AUTHOR]

Enhancing soil stability through the incorporation of straw and biochar is well documented. Nevertheless, the combined impact of straw, biochar, and nitrogen supplementation on soil aggregates and organic carbon still needs to be explored, with limited attention given to various sieving methods in the existing literature. Therefore, the current experiment used four sieving methods—routine wet sieving (RoutW), fast-wetting sieving (FastW), slow-wetting sieving (SlowW), and wetting–stirring sieving (WetS)—to investigate the effects of adding straw (0 or 4.5 t ha−1), biochar (from maize straw, 0 or 15 t ha−1), and N (0 or 100 kg ha−1) on soil aggregate stability and soil organic C in silt–loam soil of rainfed farmland in northwest China. The field experiment was started in 2014; soil samples were collected in 2021. The results revealed that straw returned, biochar, and N addition significantly increased soil mean weight diameter (MWD) and soil organic C (SOC). Compared to CN0 (zero-amendment) plots, straw returned with nitrogen addition (SN100) significantly increased the MWD of aggregates by 130.3% (RoutW), 121.66% (FastW), 73.94% (SlowW), and 91.78% (WetS) in the 0–30 cm soil layer. The addition of biochar and nitrogen (BN100) treatment showed the most significant effects on the relative slaking index (RSI), relative mechanical breakdown index (RMI), and SOC; compared with CN0 treatment, BN100 plots can reduce RSI and RMI by 42.90% and 54.66% and increase SOC by 53.27% for all soil layers. Therefore, adding organic materials with N can enhance the stability of soil aggregates and SOC of silt–loam soils in northwest China. Integrating biochar as an organic soil amendment in the agricultural practices of northwest China presents a multifaceted solution that addresses soil health, crop productivity, and environmental sustainability. The current study provides valuable insights that support adopting this innovative approach, paving the way for future sustainable agricultural practices that can benefit both the region and the global community. [ABSTRACT FROM AUTHOR]

Introduction: Codonopsis pilosula is widely sought-after in China as a substitute for the more expensive ginseng. Continuous cropping of C. pilosula supports a vibrant health-supplement industry but requires significant inputs of fertilizers which increase production costs and degrade the environment. Methods: Here, three environmentally-friendly natural fertilizers, including biochar, bacterial fertilizer, and vermicompost, were used at different concentrations (undiluted, diluted 10 times, diluted 50 times) to determine their efficacy in seed germination and growth physiology of C. pilosula in continuous cropping. Results: The results showed that biochar, bacterial fertilizer, and vermicompost with different concentrations of leachate could all increase the germination rate, germination potential and germination index of C. pilosula seeds treated with inter-root soil leachate of continuous C. pilosula; increase the activity of antioxidant enzymes (superoxide dismutase and peroxidase) in C. pilosula seedlings under the stress of inter-root soil leachate of continuous C. pilosula, reduce the over-accumulation of malondialdehyde (MDA) content, and increase the resistance of C. pilosula seedlings. After transplanting, superoxide dismutase (SOD) activity increased by an average of 16.1%. Peroxidase (POD) levels showed an average increase of 16.4%. Additionally, there was a significant reduction in the MDA content, with an average decrease of 50%, and the content of osmoticregulating substances (free proline content and soluble protein content) exhibited a significant increase. Discussion: In conclusion, biochar, bacterial manure, and vermicompost have the potential to overcome the challenges of extensive fertilizer use in continuous cropping of C. pilosula. [ABSTRACT FROM AUTHOR]

Biochar, as a soil amendment, has been widely confirmed to increase soil carbon sequestration. However, how biochar addition affects soil carbon changes during the vegetation restoration process is still unclear, which constrains our ability to explore biochar's application in the technology of soil carbon sequestration in forests. We conducted an incubation experiment on biochar and dissolved organic matter (DOM) addition to soil at three stages of revegetation (degraded land (DS), plantation forest (PS), and secondary natural forest (NS) in Changting County in Fujian province, China) to investigate the effects of vegetation restoration, biochar, DOM, and their interaction on soil CO2 emission and its relative mechanisms. We found that the accumulative release of CO2-C in the NS and PS soils was 7.6 and 6.8 times higher, respectively, in comparison to that from the DS soil. In the DS, biochar addition significantly increased the accumulative release of CO2-C, soil pH, NH4+-N content, qCO2, phenol oxidase, and peroxidase activities. Peroxidase activities were positively correlated with the accumulative release of CO2-C, and oxidase was the most important direct factor influencing the accumulative release of CO2-C in the DS. However, the accumulative release of CO2-C, soil NH4+-N content, qCO2, β-glucosidase, and N-acetylglucosaminidase activities was significantly reduced after the application of biochar in the PS and NS. These two hydrolases were positively associated with the accumulative release of CO2-C, and hydrolase was the most vital direct factor influencing the accumulative release of CO2-C from the PS and NS soils. The positive effect of DOM addition on CO2 emission under biochar application declined with a vegetation restoration age increase. Our results indicated that biochar could alter microbial physiological processes, inhibit qCO2 and hydrolase activities, and further decrease CO2 emission in relatively fertile soil from the PS and NS; but in the relatively barren soil from the DS, biochar might promote CO2 emission by stimulating microorganisms to enhance qCO2 and oxidase activities. [ABSTRACT FROM AUTHOR]

Background: Hundreds of millions of tons coal fly ash are produced annually to support economic development and industrial production. However, directly applying coal fly ash to agricultural production can decrease the land productivity and pose a threat to the ecosystem due to the poor physicochemical properties and seriously heavy metal pollution. Methods: In this study, a field experiment to investigate the effects of coal fly ash as a soil amendment was conducted in Hebei province, China. The coal fly ash (CFA) soil field was mixed with the carrier soil (CS, without containing coal fly ash) at different rates (0–40% mass content) in the 0–20 cm layer of top soil and then mixed with a rotovator. The soil was then amended with 0.45–1.80 kg·m− 2 of G1 soil amendment for planting corn. Purpose: The purpose of this study is to investigate the response mechanism of soil microbial community activities, and soil physicochemical properties to soil amendment and carrier soil in coal fly ash soil. Key results: The study found that the G1 amendment, which consisted of humic acid, polyacrylamide, zeolite powder, and FeSO4·7H2O, improved the soil chemical properties and physical structure by increasing soil bulk density and macroaggregates. The highest corn yield was observed in B5 (20% CS and 1.3500 kg·m− 2 G1). Meanwhile, the abundance of microorganisms that facilitate the circulation of soil nutrients such as Acidobacteria (77.05%), Sphingomonas (25.60%), Nitrospira (20.78%), Streptomyces (11.32%), and Gaiella (10.20%) was increased. Conclusions: Overall, our results indicate that the use of coal fly ash soil as a amendment can enhance soil sustainability by improving soil microbial functions. These findings provide a reference for the development and application of coal fly ash soil amendments. [ABSTRACT FROM AUTHOR]

To date, most studies have shown that biochar has great potential in carbon sequestration and reduction, as well as soil quality improvement. However, there is limited knowledge of its effect on soil organic carbon (SOC) fractions in tropical farmland. This study aimed to determine the impact of different types and rates of biochar applied in tropical farmlands on so SOC and its active fractions. The SOC, microbial biomass carbon (MBC), dissolved organic carbon (DOC), and soil mineralizable carbon (SMC) in the 0–30 cm soil layers under rice hull (R) and peanut shell (P) biochar treatments were measured. The results showed that the application of R and P biochar increased the contents, stocks, and cumulative stocks of SOC, MBC, and DOC in the 0–10 cm, 10–20 cm, and 20–30 cm soil layers. The contents, stocks, and cumulative stocks increased with increasing biochar application rates. Compared with CK, the ranges of the increased SOC, MBC, and DOC cumulative stocks were 10.76–46.36%, 30.04–195.65%, and 0.02–17.03%, respectively. However, the R60 and P60 had the lowest cumulative stocks of SMC, decreasing by 14.69% and 8.05%, respectively. The biochar treatment of more than 20 t ha−1 reduced the ratio of SMC:SOC and active fractions:SOC. Therefore, it can be inferred that the application of biochar improved the levels of SOC, MBC, and DOC, and the application of more than 20 t ha−1 biochar could decrease soil carbon mineralization, thus improving the stability of SOC in tropical farmlands. [ABSTRACT FROM AUTHOR]

In recent years, overuse of chemical fertilization has led to soil acidification and decreased rice yield productivity in southern China. Biochar and manure co-application remediation may have positive effects on rice yield and improve acid paddy soil fertility. This study was conducted to understand the effects of co-application of wood biochar and pig manure on rice yield and acid paddy soil quality (0–40 cm soil layers) in a 5-year field experiment. The experiment consisted of six treatments: no biochar and no fertilizer (CK); biochar only (BC); mineral fertilizer (N); mineral fertilizer combined with biochar (N + BC); manure (25% manure N replacing fertilizer N) combined with mineral fertilizer (MN); and manure combined with mineral fertilizer and biochar (MN + BC). Total nitrogen application for each treatment was the same at 270 kg nitrogen ha−1y−1, and 30 t ha−1 biochar was added to the soil only in the first year. After five years, compared with N treatments, N + BC, MN, and MN + BC treatments increased the rice yield rate to 2.8%, 4.3%, and 6.3%, respectively, by improving soil organic matter, total nitrogen, and available phosphate under a 0–40 cm soil layer. MN + BC had the strongest resistance to soil acidification among all the treatments. The interaction between fertilizers and biochar application was significant (p < 0.05) in rice yield, soil electrical conductivity (10–20 cm), and soil available phosphate (20–40 cm). Principal component analysis indicated that the effect of manure on soil property was stronger than that of biochar in the 0–40 cm soil layer. The overall rice yield and soil fertility decreased in the order of biochar + mineral fertilizer + manure > mineral fertilizer + manure > biochar + mineral fertilizer > mineral fertilizer > biochar > control. These results suggest that biochar and manure co-application is a long-term viable strategy for improving acid soil productivity due to its improvements in soil pH, organic carbon, nutrient retention, and availability. [ABSTRACT FROM AUTHOR]

The vegetation of the ecological substrate plays a crucial role in restoring shoreline ecology. This study focused on using zeolite and biochar as substrate modifiers, specifically utilizing the Cynodon dactylon from Central China for vegetation. A pot vegetation experiment was carried out to compare the effects of different ratios of zeolite and biochar. The vegetation indices, including germination index, plant height, and coverage rate, were analyzed and discussed. The results revealed that zeolite primarily influenced the germination index of Cynodon dactylon, while biochar had a more significant impact on germination percentage, germination energy, plant height, and coverage rate. This study discovered that the seed germination effect of the improved substrate initially increased with zeolite content and then decreased. The average germination percentage was 63.96%. Conversely, it decreased with an increase in biochar content, resulting in an average germination percentage of 55.45%. Zeolite and biochar caused a decrease and increase in substrate pH by −0.11 and 0.4 on average, respectively. The germination of each substrate showed a negative correlation with pH. Additionally, the average coverage and plant height decreased with an increase in biochar content. However, the inclusion of 6% zeolite led to an increase in coverage and plant height. Specifically, the average plant height increased by 3.92 cm and the coverage by 7.48%. Our research identified the optimal ratio of zeolite and biochar as 6% zeolite and 0% biochar, showcasing good overall vegetative properties. These findings offer insights for further understanding the vegetative effects of zeolite–biochar-modified substrates and optimizing substrate schemes for ecological vegetation projects. [ABSTRACT FROM AUTHOR]

Global warming is one of the eco-environmental problems of most concern to scientists. N2O, an atmospheric greenhouse gas, has been widely studied because of its high warming potential. As an excellent soil conditioner, biochar has a very broad research value and application path in the farmland. This work examined the impact of biochar application on N2O emissions reduction potential of farmland soils in northern China by meta analysis and path analysis. The results were as follows: the N2O emissions reduction potential changes corresponded with different biochar preparation materials, preparation temperature, C/N ratio and pH. Biochar is more suitable for application in soil with a bulk density < 1.3 g cm−3, sandy loam texture, neutral pH, organic matter content 20–30 g kg−1, soil C/N ratio 10–20, and total nitrogen < 2 g kg−1. At the same time, the maximum reduction of N2O emissions can be achieved in a scenario where the biochar is applied at 20 t ha−1- 40 t ha−1 and the application of nitrogen fertilizer is 100–200 kg N ha−1. Under the above ideal conditions, this study selected the data of soil mineralized nitrogen (X1), soil organic matter content (X2), soil water content (X3), average temperature (X4), total nitrogen (X5), and N2O emissions (Y) for correlation analysis and path analysis, and finally obtained the multiple stepwise regression equation between N2O emissions and various impact factors as follows: Y = -45.9102 + 0.6874X1 + 0.4634X2 + 0.3249X3 + 0.2698X4 + 0.2218X5 (R2 = 0.826, p < 0.01, n = 87). The direct relationships between N2O and soil mineralized nitrogen and soil organic matter content were very significant (P < 0.01). The second is soil water content, average temperature and total nitrogen. Indirect relationships between N2O and average temperature, total nitrogen and mineralized nitrogen were significant (P < 0.05). [ABSTRACT FROM AUTHOR]

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Fe-modified biochar (FB) and co-using Chinese milk vetch and rice straw (MR) are two effective ways for mitigating the cadmium (Cd) contamination in paddy fields in southern China. Nevertheless, the effects of FB combined with MR on Cd passivation mechanism remain unclear. In the current study, the strengthening effects of FB induced by MR were found and the mechanisms of the extracted dissolved organic matter (DOM) from the co-decomposition of MR on Cd alleviation were investigated through pot experiment and adsorption experiment. Pot experiment demonstrated that co-incorporating FB and MR decreased available Cd by 23.1% and increased iron plaque concentration by 11.8%, resulting in a 34.7% reduction in Cd concentrations in brown rice compared with addition of FB. Furthermore, co-using FB and MR improved available nutrients in the soil. The molecular characteristics of DOM derived from the decomposition of MR (DOM-MR) were analyzed by fluorescence excitation emission matrix spectroscopy-parallel factor analysis (EEM-PARAFAC) and Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS). Results showed that lignin/carboxylic-rich alicyclic molecules and protein/amino sugar were the main compounds, potentially involved in the Cd binding. Adsorption experiments revealed that the addition of DOM-MR improved the functional groups, specific surface area, and negative charges of FB, inducing the strengthening of both physisorption and chemisorption of Cd(II). The maximum adsorption capacity of Fe-modified biochar after adding DOM-MR was 634 mg g−1, 1.30 times that without the addition of DOM-MR. This study suggested that co-incorporating MR, and FB could serve as an innovative practice for simultaneous Cd remediation and soil fertilization in Cd-polluted paddy fields. It also provided valuable insights and basis that DOM-MR could optimize the performances of Fe-modified biochar and enhance its potential for Cd immobilization. Highlights: Chinese milk vetch and rice straw strengthened the Cd remediation by biochar. Soil DOM was the key influencing factor on soil Cd immobilization. DOM optimized the properties of biochar and produced richer functional groups. The combination of DOM and biochar had a higher specific surface area than biochar alone. DOM strengthened the physisorption and chemisorption capacities of Cd(II) on biochar. [ABSTRACT FROM AUTHOR]

Biochar was derived from rice straw pyrolyzed at 400°C, and biochar was added to the excess sludge at the ratio of 10% DS, 25% DS, and 50% DS as a supplementary skeleton for sludge Fenton pre-treatment. Rice husk biochar mixed with fungus residue as compost conditioner. In this study, we explored the effects of seven groups of composting materials on the composting effect and fertilizer quality under different pre-treatment methods of Fenton-pretreated sludge cake and conventional dewatered sludge cake, and different biochar additions. Specifically, we conducted a 22-day composting experiment using a composting reactor to investigate the effect of rice husk biochar combined with Fenton oxidation on the physicochemical properties of sludge composting. The results of this study showed that the FB50 group significantly increased the composting rate. Nutrient analysis showed that the FB50 group was rich in fertilizer nutrients, such as available phosphorus, and alkali-hydrolyzable nitrogen content increased. Heavy metals (Cu, Cd, Cr, Pb, Zn, Ni) met China's 'Agricultural Sludge Pollutant Control Standard' GB 4284-2018 Grade A standard, with obvious passivation and significantly reduced bioavailability. All these results suggested that biochar coupled with Fenton oxidation was more beneficial to sludge composting. [ABSTRACT FROM AUTHOR]

Biochar is produced by burning biomass under oxygen‐limited conditions, and it has been widely used as a soil amendment to improve soil functions such as nutrient retention. However, whether the impact of biochar application on soil nitrogen (N) transformation and N2O emission varies with the pyrolysis temperature remains unclear, especially in different forest types in subtropical regions. In this study, a 60‐day laboratory incubation experiment was conducted to evaluate the impact of biochar with different pyrolysis temperatures (300°C [BC300], 500°C [BC500], and 800°C [BC800]) on net N transformation rates and N2O emission in soils collected from Castanopsis kawakamii dominated natural forest (NF) and Chinese fir (Cunninghamia lanceolate, CF) plantation in subtropical China. The results showed that the application of biochar significantly increased soil ammonium (NH4+) content (p < 0.001) but reduced nitrate (NO3−) content (p < 0.001) compared with the control. The soil NH4+ content of the BC800 treatment was significantly higher than that of other treatments (p < 0.001). Biochar application significantly reduced soil net N mineralization (NRmin) and nitrification (NRnit) rate (p < 0.001), but increased net ammonification (NRamm) rate (p < 0.001). The application of biochar led to a remarkable decrease in cumulative N2O emission compared to the control (p < 0.001). In particular, soils treated with high‐temperature biochar emitted significantly lower N2O compared to other treatments (p < 0.001). The partial least squares path model demonstrated that biochar influenced N2O emission through a direct effect in NF soil and an indirect effect in CF soil. This study highlights the distinct role of biochar, particularly that produced under high pyrolysis temperatures as a soil amendment to mitigate N2O emission and promote N retention in both subtropical natural and planted forests. [ABSTRACT FROM AUTHOR]

Biochar is widely used to improve soil physical properties and carbon sequestration. However, few studies focuse on the impact of maize stalk biochar on labile organic carbon (LOC) pool and the relationship between physical properties and LOC fractions. A field positioning experiment was performed in Mollisols region of Northeast China to evaluate the influence of maize stalk biochar on the spatial distribution and temporal changes of physical properties and LOC fractions. Maize stalk biochar treatments included C1 (1.5 kg ⋅ hm-2), C2 (3 kg ⋅ hm-2), C3 (15 kg ⋅ hm-2), C4 (30 kg ⋅ hm-2), and CK (0). The results showed that maize stalk biochar increased soil water contents (SWC) and soil porosity (SP), but reduced bulk density (BD). Maize stalk biochar reduced dissolved organic carbon (DOC) contents in the 0-20 cm soil layer, ranging from 0.25 g ⋅ kg-1 to 0.31 g ⋅ kg-1 in harvest period, while increased in the 20-40 cm soil layer. In addition, the application of biochar had a significant impact on the spatial distribution and temporal change of SWC, BD, SP, DOC, hot-water extractable carbon (HWC), acid hydrolyzed organic carbon (AHC I, II), and readily oxidized organic carbon (ROC). High amounts of maize stalk biochar up-regulated the contents of soil organic carbon SOC, HWC, AHC I, AHC II, and ROC. In addition, SWC and SP were the key physical factors to affect LOC fractions. In conclusions, maize stalk biochar could improve physical properties, and then influence LOC fractions, and maize stalk biochar could be used as an organic amendment for restoring degraded soils governed by their rates of addition. [ABSTRACT FROM AUTHOR]

The cultivated land area in China is approaching the red line for farmland protection. Newly reclaimed land possesses a large exploratory potential to become a reserved land resource. Identifying a fertilization strategy is vital for improving the poor properties and weak fertility of newly reclaimed land. An experiment was conducted to study the effects of traditional compound fertilizer (Fc) or bio-organic fertilizer (Ft), alone or in combination with biochar addition (6.85 t·ha−1 and 13.7 t·ha−1) on the growth, photosynthesis, yield and quality of Chinese small cabbage (CSC) plant. The results showed that compared to single compound fertilizer application, bio-organic fertilizer application promoted the plant's growth, indicated by the plant height, stem diameter and leaf area index (LAI), and significantly enhanced the yield and dry matter accumulation of CSC. In terms of the combination with biochar, the promoting effects were positively related to the biochar addition rate in the compound fertilizer group, while it was better to apply bio-organic fertilizer alone or in combination with biochar at a low rate of 6.85 t·ha−1. The highest yield was obtained under B2Fc and B1Ft with 29.41 and 37.93 t·ha−1, respectively, and the yield under B1Ft was significantly higher than that under B2Fc. The water productivity (WP) significantly improved in response to both kinds of fertilizer combined with biochar at 6.85 t·ha−1. There was a significant difference between the photosynthetic characteristics of plants treated with single-compound fertilizer and those treated with bio-organic fertilizer. The photosynthetic characteristics increased under compound fertilizer combined with biochar, while they regressed under bio-organic fertilizer combined with biochar. The quality of CSC, especially that of soluble sugars and total phenolics, improved under single bio-organic fertilizer application compared with that under single-compound fertilizer. The nitrite content of the plants increased with increasing biochar addition rate in both fertilizer groups. In conclusion, there is a significant promoting effect of applying bio-organic fertilizer to replace chemical fertilizer alone or combining compound fertilizer with low-rate biochar addition on newly reclaimed land. It is a recommended fertilization strategy to substitute or partially substitute chemical fertilizer with bio-organic fertilizer combined with biochar in newly reclaimed land, and it is of great significance to achieve fertilizer reduction. [ABSTRACT FROM AUTHOR]

Purpose: The content of PAHs in surface soils of northeastern China is high, which causes long-term soil pollution and potential harm to human health. Influenced by the temperature, the soil in the northeast region is characterized by a long-term freeze–thaw seasonal climate, which greatly affects the process of soil remediation work. Therefore, it is necessary to study the remediation strategies of PAHs in low-temperature soils. Our group discovered that the combination of cold-tolerant fungi and bacteria was effective in degrading soil PAHs. However, we are required to further explore the choice of immobilization vector. Materials and methods: In this study, four different types of biochar (C300, C500, B300, B500) were prepared at 300 °C and 500 °C using corn cob and wheat straw of industrial and agricultural waste as precursors. We then used the cross-mixing of these four types of biochar as the carrier for Pseudomonas sp. S4 and Mortierella alpina J7, which are bacteria capable of degrading PAHs. We used the adsorption immobilization method to prepare the repair materials for PAHs degradation mixed bacteria. Results and discussion: Through comparison, the low-temperature and high-temperature mixed biochar (C300 + B500) was selected as the carrier. The results showed that mixed biochar immobilized degrading bacteria are the most effective in degrading Phe and Pyr in soil and their degradation effect was related to the mixing ratio. After 30 days of remediation at 15 °C, the best remediation effect was add immobilized mixed fungicide agent, mix biochar 1:2 using 0.67% C300 and 1.34% B500 (CBJ 1:2). Conclusions: Studies have shown that a mixture of low- and high-temperature biochar is a more promising strategy when used in combination with PAHs-degrading bacteria. [ABSTRACT FROM AUTHOR]

In the last decade, biochar application research has emerged as a hot topic in water treatment studies, which made biochar adsorption one of the primary wastewater treatment strategies. This paper presents a global bibliometric analysis of 2673 publications from the Web of Science database, spanning 2011–2022. For a comprehensive understanding of the research status and trends in biochar adsorption for wastewater treatment, the advanced quantitative and visual analysis tools (i.e., CiteSpace and ArcGIS) were employed. The results showed that China emerged as the leading country with the most published articles. The key research area is on the magnetic adsorption of biochar in wastewater. The articles summarized in the review demonstrated unequivocally that biochar can treat a wide range of wastewater even though the adsorption mechanisms of biochar on heavy metals, inorganic salts and organic pollutants in wastewater are not entirely consistent. The review further analyzes the factors affecting the performance of biochar in adsorbing pollutants from wastewater and the improvement measures of biochar functional characteristics, proposing the future research directions focusing on the improvement of the adsorption capacity of biochar products. The information synthesis and discussion would provide valuable insights on the historical, current, and future trends in biochar research, beneficial to solve the practical problems of water pollution and improve the quality of the environment. [ABSTRACT FROM AUTHOR]

Biochar is one of the most environmentally friendly and cost-effective materials that has shown potential properties for applications in various areas. Several studies have therefore been conducted in the past years, covering several aspects of biochar production, properties, and applications. This study employed both traditional and bibliometric methods to conduct a comprehensive review of the research field in the past decade (2013–2023). The Biblioshiny package in the R software and the VOSviewer tool were used for the analysis. Data from the largest research database, i.e., Scopus, was used for bibliometric analysis. The outcome of the study indicates that China sits on top in terms of research output and collaborations. An annual growth rate of 13.6 % is recorded for biochar research. The study also identified an evolution with respect to the themes studied in the past years to cover topics such as life cycle assessment, circular bioeconomy, and the techno-economics of biochar. Even though biochar's efficiency depends on the pyrolysis conditions and the nature of biomass, its development is also expected to focus on fine-tuning its properties. The environmental as well as the agronomical benefits of biochar have been well researched during the study period. This review provides stakeholders and researchers with the needed information on the most studied topics in feedstocks, production, and applications of biochar. • Recent advancements in the production and utilization of biochar are reviewed in this study. • The traditional and bibliometric review approaches were adopted for the study. • The study found an annual growth rate of 13.6 % for biochar research in the last decade. • It was found that research into biochar production and utilization has become more diversified in the last 3 years. • Most studies are focused on its utilization and economic viability in the last three years. [ABSTRACT FROM AUTHOR]

In the context of carbon neutrality, promoting resource utilization of industrial alkali lignin addressing heavy metal pollution is crucial for China's pollution alleviation and carbon reduction. Microwave pyrolysis produced functionalized biochar from industrial alkali lignin for Ni(II) adsorption. LB400 achieved 343.15 mg g−1 saturated adsorption capacity in 30 min. Pseudo-second-order kinetic and Temkin isotherm models accurately described the adsorption, which was endothermic and spontaneous (ΔGϴ < 0, ΔHϴ > 0). Quantitative analysis revealed that both dissolved substances and carbon skeleton from biochar contributed to adsorption, with the former predominates (93.76%), including mineral precipitation NiCO3 (Qp) and adsorption of dissolved organic matter (QDOM). Surface complexation (Qc) and ion exchange (Qi) on the carbon skeleton accounted for 6.3%. Higher biochar preparation temperature reduced Ni(II) adsorption by dissolved substances. Overall, biochar which comes from the advantageous disposal of industrial lignin effectively removes Ni(II) contamination, encouraging ecologically sound treatment of heavy metal pollution and sustainable resource utilization. [ABSTRACT FROM AUTHOR]

A comprehensive understanding of rice straw (RS) and biochar (BC) addition affecting soil quality, enzyme activities, bacterial community structure and grain yield is crucial. The objective of this study was to examine the dynamics of the soil microbial community impacted by the application of rice straw and biochar, and to understand the relationship between the microbial communities, soil enzymes, nutrients and grain yield of paddies. We conducted a field experiment with organic amendments under the direct seeding of paddies. The bacterial community structure in the rhizosphere was characterized using high-throughput 16S rRNA sequencing. The results showed that RS amendment increased grain yields by 8.5 and 9.9% more than with BC and the control without organic amendment (CK), respectively (p < 0.05). The abundance of bacteria associated with nitrate reduction in RS was higher than that in BC and CK, which further showed the significance of the RS-treated soil bacteria in rice nutrient utilization. A cladogram plotted using linear discriminant analysis effect size showed that Proteobacteria (Alphaproteobacteria), Acidobacteria, Firmicutes, Verrucomicrobia and Epsilonbacteraeota in the RS-treated soil increased in comparison with CK. Pearson's correlation analysis showed that enzymes activities (cellulase activity and protease activity), soil nutrition content (soil hydrolyzable nitrogen), and bacterial phyla (Nitrospinae) were positively correlated with grain yield, suggesting that the RS-treated soil improved enzyme activities, soil nutrition content, and bacterial abundance, which in turn increased grain yield. The results indicated that RS-treated bacterial communities combined with soil enzymatic activities strengthen the transformation of nutrients, suggesting that the interactions play an important role in enhancing the grain yield of paddy rice. These results provide new insights and a theoretical basis for studying the changes in soil microbial communities with the application of RS and BC in Northeastern China. [ABSTRACT FROM AUTHOR]

Global climate warming and increased climate variability may increase the number of annual freeze–thaw cycles (FTCs) in temperate zones. The occurrence of more frequent FTCs is predicted to influence soil carbon and nitrogen cycles and increase nitrogen leaching. Biochar has the potential to increase soil organic carbon storage and decrease nitrogen leaching. This study aims to investigate the impact of freeze–thaw cycles (FTCs) on soil nitrogen leaching in temperate zones, considering the potential exacerbation of FTCs due to global climate warming and increased climate variability. This study focuses on how biochar, a carbon-rich material produced from biomass, might mitigate nitrogen leaching by influencing soil characteristics. This study explores the interactions between different laboratory-simulated FTC frequencies (ranging from 0 to 12 cycles) and various biochar addition ratios (0%, 2%, 4%, and 6% w/w) on soil nitrogen leaching based on a total of 60 soil columns. Pearson correlations between the soil quality indicators and nitrogen leaching characteristics were detected, and partial least squares path modeling (PLS-PM) was used to assess the effects of the FTCs, biochar addition ratios, and soil quality indicators on the nitrogen leaching content. The results showed that the amount of leached soil NH4+-N and NO3−-N reached 0.129–1.726 mg and 2.90–7.90 mg, respectively. NH4+-N and NO3−-N first increased and then decreased under the FTCs, with the highest values being observed after the 6th FTC. As the biochar addition ratio increased, the NH4+-N and NO3−-N contents decreased. Correlation analysis showed that the nitrogen leaching content was significantly related to the soil pH, soil organic matter (SOM), NH4+-N content, and microbial biomass carbon content (MBC) (p < 0.01). The results of the conceptual path model revealed that nitrogen leaching characteristics were significantly affected by the pH, SOM, soil nitrogen content, and biochar addition ratio. Our results suggest that biochar addition can help reduce nitrogen leaching in farmland soil in areas with black soil and seasonal freeze–thaw cycles. [ABSTRACT FROM AUTHOR]

The composition of microbial communities and the functioning of ecosystems are greatly influenced by the nutrient inputs. Despite this fact, our knowledge regarding the impact of phosphorus (P) inputs on soil P availability and microbial community structures in subtropical acidic soils remains limited. We hypothesized that diverse P inputs, incubation temperatures, and soil types could significantly alter soil P availability and microbial communities. To address this gap, we conducted a laboratory incubation experiment, investigating the effects of biochar and inorganic P amendments on soil available P, soil pH, acid phosphatase enzymes, and bacterial abundance. We employed two different incubation temperatures (15 °C and 25 °C) using acidic paddy soil and red soil from the subtropical Southern China region. Our results indicate a notable increase in soil pH, reaching 37% and 39% at 15 °C and 40% and 40.6% at 25 °C, respectively, following the application of biochar and inorganic P amendments in paddy soil. In the case of red soil, we observed pH increases of 41% and 43% at 15 °C and 44% and 45% at 25 °C after the application of biochar and inorganic P amendment, respectively. The addition of inorganic P amendment resulted in the highest available P contents in paddy soil, reaching 111.47 mg/kg at 15 °C and 100.17 mg/kg at 25 °C, respectively. However, Proteobacteria decreased after inorganic P addition, which showed that P might not be the only limiting nutrient for various bacterial communities. Bacterial diversity and richness indices were found to be higher after biochar application in both soils. Gemmatimonadetes, Acidobacteria, and Actinobacteria were found to be strongly influenced by incubation temperatures, whereas most of the top abundant bacterial phyla, such as Gemmatimonadetes, Actinobacteria, Chloroflexi, Acidobacteria, Planctomycetes, Firmicutes, Patescibacteria, and Bacteroidetes, were highly dependent on soil type. At the genus level, various important P solubilizing genera (Pseudomonas, Bradyrhizobium, Streptomyces jietaisiensis, Massilia) significantly increased after biochar and inorganic P addition in both soils. The correlation analysis proved that P-solubilizing genera were significantly associated with changes in soil pH, as well as soil available P after biochar and inorganic P addition. Conclusively, in a short-term incubation experiment, inorganic P amendment greatly increased the soil pH and available phosphorus contents compared to biochar and control treatments; however, the microbial community was observed to be strongly associated with biochar application, soil type, and incubation temperature. [ABSTRACT FROM AUTHOR]

Microplastic pollution in sugarcane areas of China is severe, and reducing the ecological risks is critical. Biochar has been widely used in soil remediation. This study aims to explore the effects and mechanisms of microplastics combined with or without biochar on sugarcane biomass, soil biochemical properties in red soil through a potted experiment. The results show that, compared with control (CK), treatments with microplastics alone reduced the dry biomass of sugarcane, soil pH, and nitrogen (N) and phosphorus (P) contents by an average of 8.8%, 2.1%, 1.1%, and 2.0%, respectively. Interestingly, microplastics combined with biochar could alleviate the negative effects of microplastic accumulation on sugarcane growth and soil quality. There were significant differences in the bacterial community alpha diversity indices and compositions among different treatments. Compared with CK, treatments with microplastics alone obviously decreased the observed operational taxonomic units (OTUs) and the Chao1 and Shannon indices of soil total bacteria (16S rRNA gene-based bacteria) while increasing them in phoD-harboring bacteria. Microplastics combined with biochar treatments significantly increased the abundance of Subgroup_10 for the 16S rRNA gene and treatments with microplastics alone significantly increased the relative abundance of Streptomyces for the phoD gene compared to CK. Moreover, compared with microplastics alone, the treatments with microplastics combined with biochar increased the relative abundance of Subgroup_10, Bacillus, Pseudomonas in soil total bacteria, and Amycolatopsis and Bradyrhizobium in phoD-harboring bacteria, most of which can inhibit harmful bacteria and promote plant growth. Additionally, different treatments also changed the abundance of potential microbial functional genes. Compared to CK, other treatments increased the abundance of aerobic ammonia oxidation and denitrification but decreased the abundance of nitrate respiration and nitrogen respiration; meanwhile, these four functional genes involved in N cycling processes were obviously higher in treatments with microplastics combined with biochar than in treatments with microplastics alone. In conclusion, microplastics combined with biochar could alleviate the negative effects of microplastic accumulation on sugarcane biomass by altering soil nutrients and microbial community structure and function. [ABSTRACT FROM AUTHOR]

The beneficial utilization of potentially increasing urban green waste (UGW) is critical for sustainable urban development in China. In this study, UGW was pyrolyzed at different temperatures, and the resulting biochar was used to amend Cd-contaminated soils to grow cabbage. Our results showed that the Cd adsorption capacity of UGW-biochar was positively correlated with the surface area, O/C, and (O+N)/C value of biochar. Furthermore, UGW-biochar was incorporated into three Cd-contaminated soils, including one acidic soil and two neutral soils, to assess its impact on the availability of Cd. The most substantial reduction in the concentration of available Cd was observed in the acidic soil, of the three tested soils. In the neutral soils, a more substantial reduction was found in the heavily Cd-contaminated soil compared to the lightly Cd-contaminated soil. UGW-biochar amendments to the three Cd-contaminated soils resulted in an increase in the cabbage biomass in acidic soil, whereas in neutral soils, it increased in lightly contaminated soils but decreased in heavily contaminated soils. Additionally, the Cd bioaccumulation factor (BCF), translocation factor (TF), and removal efficiency (RE), as impacted by the biochar application, were calculated in the lightly Cd-contaminated soil–cabbage system. The BCF decreased from 5.84 to 3.80 as the dosage of the UGW-biochar increased from 0% to 3%, indicating that the UGW-biochar immobilized Cd and reduced its bioaccumulation in cabbage roots. Based on our investigations, UGW-biochar effectively immobilizes Cd by reducing its mobility and bioavailability in a lightly contaminated environment matrix. [ABSTRACT FROM AUTHOR]

The indiscriminate use of nitrogen fertiliser (NF) is a obstruction to improve soil quality and crop yields. However, the effect of biochar and NF on soil microbial ecosystem (SME) and crop yields is unknown. A five-year field experiment in China aimed to evaluate the effects of biochar and nitrogen fertiliser (NF) combination on soil structure, C-to-N ratio (CNR), microbial biomass, and spring maize yield. Biochar and NF were applied at different rates, and the combined application resulted in a soil solid–liquid–gas ratio closer to the ideal value. The use of biochar alone and in combination with NF significantly increased soil's C, N, and CNR. A moderate application of biochar and NF resulted in favourable biological and chemical properties of the soil. The application of biochar and NF at moderate levels led to an increase in SME, with the B8N150 producing the highest yield. The highest yield of B8N150 represents a 24.25% increase compared to the unfertilized control and a 9.04% increase compared to B0N150. Moderate use of biochar and NF could be beneficial in areas with similar climatic conditions. [ABSTRACT FROM AUTHOR]

Massive amount of food waste has been generated annually, posing a threat to ecological sustainability and the social economy due to current disposal methods. Urgent action is needed worldwide to convert the traditional pathway for treating food waste into a sustainable bioeconomy, as this will significantly benefit food chain management. This study explores the use of pyrolysis to produce different types of food waste biochars and investigates their adsorption capabilities for removing Cd2+ and Pb2+ in aqueous solution. The results indicated that co-pyrolysis biochar from fresh food waste and rice husk (FWRB) exhibited superior adsorption performance for Cd2+ (61.84 mg·g−1) and Pb2+ (245.52 mg·g−1), respectively. Pseudo-second-order kinetics (0.74 ≤ R2 ≤ 0.98) and Langmuir isotherms (0.87 ≤ R2 ≤ 0.98) indicated that the immobilized Cd2+ and Pb2+ on biochars were mainly attributed to the chemisorption, including precipitation with minerals (e.g., carbonates, silicates, and phosphate), complexation with functional groups (–OH), cation exchange (–COO−), and coordination with π-electrons. Furthermore, FWRB demonstrated reduced EC and Na content in comparison to food waste digestate biochar (FWDB) and food waste digestate co-pyrolysis with sawdust biochar (FWSB), with levels of Cd and Pb falling below China's current guideline thresholds. These findings suggested that co-pyrolysis of fresh food waste with rice husk could be applicable to the recycling of food waste into biochar products for heavy metal stabilization in contaminated water and soils. [ABSTRACT FROM AUTHOR]

With the existing model of chemical fertilizer application faces, improving grain yield and quality is challenging. Fragrant rice is known for its distinctive aroma and flavor, but it generally produces less grain than non-fragrant rice varieties. Limited research has been conducted on the potential of biochar as a solution for increasing the grain yield of fragrant rice. In a two-year field trial conducted in 2022 and 2023, two fragrant rice cultivars, Meixiangzhan2 (MXZ2) and Xiangyaxiangzhan (XYXZ), were selected as the experimental materials. These rice cultivars were subjected to four different rates of biochar application: no biochar treatment(T1); biochar with 0.375 t ha−1 (T2); biochar with 0.75 t ha−1 (T3); and biochar with 1.50 t ha−1 (T4). The results showed that the grain yield of both cultivars increased to an extent in both 2022 and 2023 (an 8.57–33.77% increase for MXZ2; a 6.00–21.59% increase for XYXZ). Furthermore, under the T2, T3, and T4 treatments, there was an increase in the number of effective panicles, seed setting rate, 1000-grain weight, biomass accumulation, net photosynthetic rate, and intercellular CO2 concentration. However, the transpiration rate and stomatal conductance decreased. The content of 2-acetyl-1-pyrroline (2-AP) increased with an increased rate of biochar application, and the highest content was observed under the T4 treatment (153.54–178.32 µg kg−1 in 2022; 163.93–180.28 µg kg−1 in 2023). The activities of proline dehydrogenase (PDH) and 1-pyrrolin-5-carboxylic acid synthase (P5CS), as well as the contents of proline (PRO), 1-pyrrolin-5-carboxylic acid (P5C), ∆1-pyrroline, and methylglyoxal, were improved under the T2, T3, and T4 treatments compared to the T1 treatment. Moreover, under the T2, T3, and T4 treatments, the brown rice rate, milled rice rate, and head rice rate increased, while the chalkiness degree and chalk rice rate decreased. Our correlation analysis showed that grain yield was positively correlated with total biomass accumulation, the number of grains per panicle, and the seed setting rate. Additionally, the content of 2-AP showed positive correlations with PRO, P5C, ∆1-pyrroline and methylglyoxal, and the activities of PDH and P5CS. In conclusion, applying biochar at a rate of 1.5 t ha−1 can be more effective in increasing the grain yield and 2-AP content of fragrant rice. [ABSTRACT FROM AUTHOR]

Biochar has gained significant attention in agricultural and environmental research over the last two decades. This comprehensive review evaluates the effects of biochar on soil organic carbon (SOC), emission of non-CO2 greenhouse gases, and crop yield, including related mechanisms and major influencing factors. The impacts of biochar on SOC, methane and nitrous oxide emissions, and crop yield are controlled by biochar and soil properties and management practices. High-temperature biochar produced from lignin-rich feedstocks may decrease methane and nitrous oxide emissions in acidic soils and strengthen long-term carbon sequestration due to its stable aromatic structure. In contrast, low-temperature biochar from manure may increase crop yield in low-fertility soils. Applying biochar to farmlands in China can increase SOC content by 1.9 Pg C and reduce methane and nitrous oxide emissions by 25 and 20 Mt CO2-eq year−1, respectively, while increasing crop yields by 19%. Despite the increasing evidence of the positive effects of biochar, future research needs to explore the potential factors that could weaken or hinder its capacity to address climate change and secure crop production. We conclude that biochar is not a universal solution for global cropland; however, targeted applications in fields, landscapes, or regional scales, especially in low fertility and sandy soils, could realize the benefits of biochar as a climate-smart measure. Highlights The findings of research on biochar's effects on soil C sequestration, GHG mitigation, and crop production were summarized. The factors influencing the impact of biochar on soil functioning were reviewed. The effects of biochar on soil C sequestration and GHG mitigation in farmlands of China were quantified. [ABSTRACT FROM AUTHOR]

This study aims to quantitatively analyze the space-time effect and influence mechanism of biochar application on tomato yield and quality. Meanwhile, an optimal application amount of biochar was determined in tomato production. A metaanalysis was carried out to evaluate the effects of biochar characteristics, soil conditions, field measures, and spatiotemporal patterns on the tomato yield and quality under biochar application. Literature was searched to integrate the published field data from the relevant experiments. Meanwhile, path analysis was constructed to explain the interaction among the factors. Nonbiochar application was used as the control treatment. 24 valid cases were screened from the collected literature to obtain 138, 66, 54, 41, 52, and 14 datasets on the yield, Vc, soluble sugars, soluble solids, sugar-acid ratio, and nitrate content of tomatoes, respectively. The experiments lasted from 2012 to 2021. The effect size was determined as the indicator in the meta-analysis. Important factors were selected for the effectiveness of biochar production. The top three factors were identified in the descending order of direct flux coefficients. The results showed that the biochar application significantly increased the tomato yield, fruit Vc, soluble sugar, and soluble solids content by 30.7% (95% CI: 27.6%-33.9%), 13.8% (95% CI: 10.8%-16.9%), 6.7% (95% CI: 3.3%-10.2%), and 10.7% (95% CI: 5.8%-15.8%), respectively, whereas, significantly reduced the tomato fruit nitrate content by 3.1% (95% CI: -6.7%-0.8%), and there was the non-significant effect of 2.3% (95% CI: -3.0%-7.9%) on the increase in the tomato fruit sugar to acid ratio. No publication bias was found, because both yield and quality data were linearly correlated by the publication bias test, indicating that the data conformed to the normal distribution (P <0.01). The groups of data with and without biochar application were almost always distributed within the confidence interval of the normal percentile plot. Subgroup analysis of tomato yield showed that the effect of biochar on tomato yield had a significant temporal and regional pattern. The effect of biochar application on tomato yield showed a fluctuating growth trend. The increasing tomato yield was found in North China, where there was no obvious in Northeast China. There was a positive correlation between soil organic matter content and tomato yield increase rate, whereas, a negative correlation between soil pH value and tomato yield increase rate. The tomato yield increase rate increased first and then decreased with the increase in the soil's total nitrogen and potassium nitrate content. Field management measures on tomato yield showed that a yield increase of 37.8% (95% CI: 33.5%-42.1%) was achieved when biochar was applied at a rate of ＞40-80 t/hm². The optimal combination was achieved in the biochar pyrolysis temperatures of 400-600 °C and biochar pH values of ＞8-9. The application amount of biochar, pH value of biochar, and yield year were the three main factors on the yield-increasing effect of biochar. The finding can also provide theoretical support for the optimal biochar application rates in tomato production. [ABSTRACT FROM AUTHOR]

Background: Nitrogen (N) is an essential plant nutrient that limits growth in most terrestrial ecosystems, and to compensate for this, biochar (BC) is often utilized to reduce soil N losses and thus improve yields. However, optimizing root morphology with BC to help reduce N fertilization use and achieve consistent yields has not been widely investigated. Methods: To address this, a two-year wheat field experiment was conducted in the drylands of the Loess Plateau in China. BC was applied at 0, 10, 20, and 30 t ha− 1 (BC0, BC10, BC20, and BC30, respectively) along with two N fertilization treatments (90 and 120 kg N ha− 1; N90 and N120, respectively). Results: The results showed that BC promoted root growth in 2017–2018 (normal year) and reduced excessive root growth in 2018–2019 (wet year). The root strategy that resulted from the BC treatments reduced the variation in mineral nitrogen storage (ΔMNS) in the soil profile, thus supporting the efficient use of water and N for higher yields and partial factor productivity of N (PFPN), especially with the N120BC20 treatment. Furthermore, the PFPN was higher with the N90BC20 treatment than with the N120BC20 treatment, but there was no significant difference in yield. These results thus indicate that BC can compensate for the yield reduction caused by reduced N fertilizer use. Conclusions: Our study provides different insights into potential strategies to reduce N applications in semiarid farmland and other rain-fed cropping regions using a BC-optimized root system strategy. [ABSTRACT FROM AUTHOR]

Soil salinization is a major threat to crop production. Biochar and aluminum sulfate as soil amendments are critical for improving rice (Oryza sativa L.) productivity under saline-sodic conditions. This study explored the effects of rice-husk biochar and aluminum sulfate on rice growth, biomass, yield, and soil properties under saline-sodic conditions. The experiment was carried out in an experimental field located at the Jilin Agricultural University, China. Five treatments, viz., T0 (no biochar, no aluminum sulfate, no nitrogen), T1 (no biochar, no aluminum sulfate, with NPK), T2 (aluminum sulfate and NPK), T3 (biochar and NPK), and T4 (biochar, aluminum sulfate, and NPK), arranged in a completely randomized design with five biological replicates, were assessed. Compared to T0, plant height, tiller number, leaf dry weight, panicle dry weight, sheath dry weight, stem dry weight, and total dry biomass significantly increased by 14.67%, 56.39%, 60.13%, 59.53%, 39.00%, 58.36%, and 55.99%, respectively, with T1. Compared to T0, the grain yield significantly increased by 82.79% with T1. Additionally, biochar and aluminum sulfate applications significantly decreased the Na+ concentration in different rice organs and considerably increased the K+ concentration and consequently, the K+/Na+ ratio. Moreover, compared to the control, the soil pH, Ca2+, Mg2+, CO32-, and Cl- concentrations under T1, T2, T3, and T4 treatments were substantially improved. Therefore, biochar and aluminum sulfate applications can alleviate saline-sodic stress, improve soil health, and increase rice productivity on saline-sodic soils. The study findings are anticipated to help develop new management strategies for improving rice production under saline-sodic conditions. [ABSTRACT FROM AUTHOR]

Extracellular enzymatic activity plays an important role in carbon (C), nitrogen (N), and phosphorous (P) cycling, and consequently, serves as an indicator for soil function. However, microbial activities are inhibited in degraded lands due to nutrition limitations, which pose a challenge to ecological management. We investigated the effects of maize biochar addition (1, 3, and 5%) on soil and enzyme stoichiometries in a post‐mining area in Shanxi province. The results showed that soil organic C and total N increased significantly with increasing biochar addition, leading to significant increases in soil C:P (by 157.9%) and N:P (by 76.1%) under 5% of addition. Biochar addition stimulated enzyme activities significantly, and the maximum of enzyme activities occurred in treatment of 5% addition. Soil enzyme C:N increased significantly following biochar addition, while enzyme C:P and N:P decreased at 5% biochar addition. Vector analysis indicated that microbial activity tended to be limited by soil N before addition, whereas it was limited by P availability at high biochar addition. This was mainly because that biochar addition could promote sorption of P and lower P bioavailability in soil. Our research suggested that biochar application could substantially improve soil nutrition status and microbial activity in infertile land, however, it would likely result in imbalances between substrate stoichiometry and microbial demand. The result might provide a reference for the management of biochar application during soil restoration. [ABSTRACT FROM AUTHOR]

Developing efficient and clean technology for the preparation of activated carbon from agricultural and forestry waste biomass is of great significance for China's dual carbon strategy. The rapid pyrolysis of agricultural and forestry waste biomass generates a large amount of biochar. The current research focus is on cost-effective and large-scale conversion of biochar into activated carbon. Using Masson pine biochar as the raw material, N2/CO2 mixed gas was used to simulate the circulating fluidized bed high- temperature flue gas, and water vapor was introduced as an activating agent to prepare activated carbon through activation of the biochar. Through single-factor experiments, the influence of water vapor flow rate, activation temperature, and activation time on the iodine adsorption value and yield of activated carbon were explored to determine the optimal preparation conditions. The physicochemical properties and structure of the activated carbon were characterized using an automatic physical and chemical adsorption instrument, scanning electron microscope, and Fourier transform infrared spectroscopy. The effects of pH, adsorption time, activated carbon dosage and initial Cu2+ concentration (mass concentration) on the adsorption performance of activated carbon for Cu2+ were investigated. The adsorption mechanism of Cu2+ on activated carbon was studied using kinetic and isotherm models. The research shows that under the optimal preparation conditions (high-temperature flue gas flow rate of 100 mL/min, water vapor flow rate of 0.9 mL/min, activation temperature of 850 °C and activation time of 2.5 h), the activated carbon yield is 7.32%, the iodine adsorption value is 1914 mg/g, and the specific surface area is 1556 m²/g. The functional groups on the surface contain various chemical bonds such as O--H, C--O, C=C and C=O bond. Under the optimal adsorption process conditions (pH of 5.5, adsorption time of 30 minutes, activated carbon dosage of 1.5 g/L and initial Cu2+ concentration of 10 mg/L), the maximum removal rate of Cu2+ is 99.97%, and the residual Cu2+ concentration is 0.003 mg/L, which complies with China's drinking water standards ( < 1 mg/L). The pseudo-second-order kinetic model and Langmuir model can better fit the adsorption process, indicating that the adsorption is a monolayer chemical adsorption, and the intraparticle diffusion is not the only rate-controlling step. [ABSTRACT FROM AUTHOR]

Considering the impacts of global climate change, paths for sustainable development are of particular importance. Biochar has multiple advantages, including but not limited to climate change mitigation, waste management, soil fertility improvement, and pollution remediation. Forest soils play a significant role in terrestrial ecosystems. The application of biochar in forest soils (ABFS) is therefore considered an essential tool for improving soil quality, capturing carbon, and reducing greenhouse gas emissions. The Web of Science Core Collection database was utilized for the bibliometric analysis of ABFS publications published between 2002 and 2022. Three bibliometric software were used to analyze bibliometrics, networks, and research directions for ABFS: Bibliometrix, VOSviewer, and CiteSpace. The analysis shows that research on ABFS is always rapidly developing. Research on ABFS is engaged globally in a complex network of collaborations, and the main research has occurred in China and the United States. Collaboration among authors is relatively diffuse. Research on ABFS involves interdisciplinary integration. In the early stages of research, the origin of biochar (history and boreal forests) and its characteristics (dynamics, nitrogen content, and chemical composition) were the focus of attention. As research progressed, more attention was given to ABFS (carbon, organic matter, vegetation, and heavy metals). Our research shows that while ABFS research has a certain history, its development trend has been consistently upward and shows no signs of declining. Thus, future research will likely concentrate on ABFS. Due to the complexity of biochar functions, ample research opportunities exist in ABFS. [ABSTRACT FROM AUTHOR]

To evaluate the effects of application of biochar and straw return for consecutive years on N2O emissions and crop yields in North China, a three-year field experiment of applying biochar and straw following a ten-year application was conducted in a wheat–maize rotation system. Four treatments were set up, including F (NPK fertilizer only); FB (NPK fertilizer + 9.0 t·ha−1 biochar); FS (NPK fertilizer + straw); and FSB ((NPK fertilizer + 9.0 t·ha−1 biochar combined with straw). The results showed that compared with the F treatment, the FB treatment significantly reduced soil N2O emissions by 20.2%, while the FS and FSB treatments increased it by 23.7% and 41.4%, respectively. The FB treatment reduced soil N2O emissions by 15.1% in the wheat season and 23.2% in the maize season, respectively. The FS and FSB treatments increased the N2O emissions by 20.7% and 36.7% in the wheat season, respectively, and by 25.5% and 44.2% in the maize season, respectively. In the wheat season, the soil water content (SWC), NO3−-N content and pH were the main influencing factors of the soil N2O emissions. In the maize season, SWC and NO3−-N content were the main influencing factors. In addition, the FB, FS and FSB treatments increased the crop yield by 4.99%, 8.40% and 10.25% compared with the F treatment, respectively. In conclusion, consecutive application of biochar can significantly reduce N2O emissions and improve crop yield. Although FS and FSB treatments can also improve the crop yield, they are not beneficial to suppressing N2O emissions. Therefore, the successive application of biochar is an effective measure to reduce N2O emissions and maintain crop yield. [ABSTRACT FROM AUTHOR]

Biochar amendment is a recently promoted agricultural management strategy that can exert distinct impacts on reducing greenhouse gas (GHG) emissions and improving soil fertility and crop productivity. This study aims to evaluate the combined effects of biochar and nitrogen (N) fertilizer on soil aggregation, nitrous oxide (N2O) emission, global warming potential (GWP), vegetable yield, and greenhouse gas intensity (GHGI). The experiments were conducted in a vegetable field with two consecutive vegetable crops in 2019 and 2020 in southeastern China. There were four treatments: control (CK), conventional N fertilizer (U), biochar applied at 15 t ha−1 with N fertilizer (UB1), and biochar applied at 30 t ha−1 with N fertilizer (UB2). The results indicate that while N application significantly increased N2O emission of the vegetable field, both UB1 and UB2 led to significant reductions of the total N2O emission, GWP, and yield-scaled GHGI as well as significant growth of the total vegetable crop yield compared with U. However, no significant differences have been found in N2O emission, GWP, crop yield, and yield-scaled GHGI between UB1 and UB2. Meanwhile, biochar application in addition to N fertilizer did not result in any significant change in the soil water-stable aggregate size distribution and stability compared with U. Soil water-stable aggregates smaller than 0.25 mm and those larger than 5 mm have been found to significantly impact N2O emission and vegetable yield. [ABSTRACT FROM AUTHOR]

Recently, biochar (B) and vermicompost (V) have been widely used as amendments to improve crop productivity and soil quality. However, the ameliorative effects of biochar and vermicompost on the continuous cropping of pepper under open-air conditions, particularly in the karst areas of southwestern China, remain unclear. A field experiment was conducted to study the effects of biochar and vermicompost application, alone or in combination, on the yield, quality, nutrient accumulation, fertilizer utilization, and economic benefits of continuous pepper cropping from 2021 to 2022. The experiment included six treatments: CK (no fertilizer), TF (traditional fertilization of local farmers), TFB (TF combined with biochar of 3000 kg·ha-1), TFV (TF combined with vermicompost of 3000 kg·ha-1), TFBV1 (TF combined with biochar of 1500 kg·ha-1 and vermicompost of 1500 kg·ha-1), and TFBV2 (TF combined with biochar of 3000 kg·ha-1 and vermicompost of 3000 kg·ha-1). Compared with the TF treatment, biochar and vermicompost application alone or in combination increased the yield of fresh pod pepper by 24.38–50.03% and 31.61–88.92% in 2021 and 2022, respectively, whereas the yield of dry pod pepper increased by 14.69–40.63% and 21.44–73.29% in 2021 and 2022, respectively. The application of biochar and vermicompost reduced the nitrate content and increased the vitamin C (VC) and soluble sugar content of the fruits, which is beneficial for improving their quality. Biochar and vermicompost application alone or in combination not only increased nutrient uptake but also significantly improved agronomic efficiency (AE) and recovery efficiency (RE). In addition, although the application of biochar or vermicompost increased production costs, the increase in yield improved net income (ranging from 0.77 to 22.34% in 2021 and 8.82 to 59.96% in 2022), particularly in the TFBV2 treatment. In conclusion, the use of biochar and vermicompost amendments had a positive effect on the productivity and economic benefits of continuous pepper cropping, and the co-application of biochar and vermicompost could be an effective nutrient management strategy for the continuous cropping of pepper in the karst mountain areas of southwest China. [ABSTRACT FROM AUTHOR]

Routine maintenance of fruit trees generates a substantial quantity of pruning waste each year. This waste is potential feedstock for producing energy, materials, and other products. The feasibility of making biochar from the waste via pyrolysis was evaluated. The effects of seven tree species, different pruning sites, and temperature on the pyrolysis process, and the physicochemical properties of the biochar were studied. Pyrolysis of different tree species at 500 °C yielded 27.5 to 33.3% biochar, with a high calorific value (approximately 30 MJ/kg), low ash content (approximately 4%), and capturing up to 60% of the carbon element present. Simultaneously, when the temperature was increased from 400 to 700 °C, the yield of biochar decreased from 35.8% to 24.3%, but the properties improved with the higher heating value rising from 29.2 to 31.3 MJ/kg and the iodine value from 234 to 252 mg/g. The biochar has a good pore structure with a specific surface area of 237 m2/g, total pore volume of 0.175 cm3/g, and average pore size of 2.96 nm. In general, biochar from the pyrolysis of fruitwood pruning waste generated here could be an ideal feedstock to produce high-value-added products, such as solid fuels, activated carbon, and electrode materials. [ABSTRACT FROM AUTHOR]

With the gradual change of climate, the organic matter and nutrients in the soil are constantly losing. It induces the creation of saltwater alkali land and quickens soil degradation, both of which further lower productivity. It will eventually lead to a serious food catastrophe. As as a consequence, the research conducted an experimental analysis on the effects of straw returning and biological carbon on saline alkali land development in northeast Jiangsu University, with the goal of addressing the issue of weak soil internal structure in some places of northeast China. The experiment analyzed the growth and photosynthesis dynamics, material accumulation and transformation, root activity, soil physical and chemical properties, and the spike characteristics of Kenjiandao 5, respectively. The experimental results showed that biochar and straw returning could effectively improve rice's growth rate and effective tillering. Among the biochar returning treatments, 4 treatments had the highest traumatic discharge, with an increased rate of 3.13–37.65%, and 6 treatments had the highest traumatic discharge, 29.96% higher than CK. At the same time, biochar and straw returning to the soil can effectively improve the organic matter in the soil and reduce its pH value. Compared with CK, the highest increase is 27.80%. In general, the use of biological carbon and straw return can effectively optimize the soil structure, increase the yield, reduce the waste of straw resources, and have a strong practical effect on the actual saline alkali land improvement in Northeast China. [ABSTRACT FROM AUTHOR]