Biochar Input Research Articles

Biochar effects on crop yield variability

Context or ProblemNumerous studies have demonstrated that biochar application can increase crop yield by improving soil properties and health. Yet, these studies, however, neglected how biochar alters yield variability across years – reflecting the yield stability. Objective or Research questionThis study aimed to investigate the effects of biochar application on crop yield variability. MethodsPublished data from 38 experimental sites were collected from the Web-of-Science. Two-thirds of the data were originated from three main staple crops: maize, wheat, and rice. The remaining were from rapeseed, soybean, sweet potato, and peppermint. Biochar effects on crop yield and its variability as well as their driving factors were analyzed by linear mixed models depending on soil conditions, field management practices, and climate types. ResultsBiochar increased the crop yield globally by 14 %, especially in soils with low pH (< 5.5), low nitrogen (N) and phosphorus (P) inputs (≤ 120 kg N ha−1, < 35 kg P ha−1), with high biochar inputs (≥ 20 Mg ha−1), and under crop rotation. Biochar increased crop yields by 12 % in short-term (≤ 5 years) and 21 % in long-term (> 5 years) experiments. Biochar increased yield variability by 42 % in acidic soils (pH < 5.5) and by 24 % with low N inputs (≤ 120 kg N ha−1), mainly because its liming and fertilization effects were short-lasting within the first few years. The yield variability after biochar application decreased with the increase in mean annual temperature, inter-annual variabilities of temperature and precipitation, but with the decrease in mean annual precipitation in the growing season. Yield variability under biochar increased in short-term experiments by 27 %, but there was no change (0 %) in long-term experiments because of the higher yield gains and resistance to fluctuating weather conditions. Therefore, crop yield variability decreased with increasing yield in long-term experiments. ConclusionsBiochar application increased short-term variability of crop yields, but its long-term variability remained unaffected. Implications or SignificanceThis study highlights that biochar can support steadily future crop production in the long run.

Recent progress and potential future directions to enhance biological nitrogen fixation in faba bean (Vicia faba L.).

The necessity for sustainable agricultural practices has propelled a renewed interest in legumes such as faba bean (Vicia faba L.) as agents to help deliver increased diversity to cropped systems and provide an organic source of nitrogen (N). However, the increased cultivation of faba beans has proven recalcitrant worldwide as a result of low yields. So, it is hoped that increased and more stable yields would improve the commercial success of the crop and so the likelihood of cultivation. Enhancing biological N fixation (BNF) in faba beans holds promise not only to enhance and stabilize yields but also to increase residual N available to subsequent cereal crops grown on the same field. In this review, we cover recent progress in enhancing BNF in faba beans. Specifically, rhizobial inoculation and the optimization of fertilizer input and cropping systems have received the greatest attention in the literature. We also suggest directions for future research on the subject. In the short term, modification of crop management practices such as fertilizer and biochar input may offer the benefits of enhanced BNF. In the long term, natural variation in rhizobial strains and faba bean genotypes can be harnessed. Strategies must be optimized on a local scale to realize the greatest benefits. Future research must measure the most useful parameters and consider the economic cost of strategies alongside the advantages of enhanced BNF.

Microbial mechanisms of organic matter mineralization induced by straw in biochar-amended paddy soil

Combined straw and straw-derived biochar input is commonly applied by farmland management in low-fertility soils. Although straw return increases soil organic matter (SOM) contents, it also primes SOM mineralization. The mechanisms by which active microorganisms mineralize SOM and the underlying factors remain unclear for such soils. To address these issues, paddy soil was amended with 13C-labeled straw, with and without biochar (BC) or ferrihydrite (Fh), and incubated for 70 days under flooded conditions. Compound-specific 13C analysis of phospholipid fatty acids (13C-PLFAs) allowed us to identify active microbial communities utilizing the 13C-labeled straw and specific groups involved in SOM mineralization. Cumulative SOM mineralization increased by 61% and 27% in soils amended with Straw + BC and Straw + Fh + BC, respectively, compared to that with straw only. The total PLFA content was independent of the straw and biochar input. However, 13C-PLFAs contents increased by 35–82% after biochar addition, reflecting accelerated microbial turnover. Compared to that in soils without biochar addition, those with biochar had an altered microbial community composition-increased amounts of 13C-labeled gram-positive bacteria (13C-Gram +) and fungi, which were the main active microorganisms mineralizing SOM. Microbial reproduction and growth were susceptible to nutrient availability. 13C-Gram + and 13C-fungi increased with Olsen P but decreased with dissolved organic carbon and NO3-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{NO}}_{3}^{ - }$$\\end{document} contents. In conclusion, biochar acts as an electron shuttle, stimulates iron reduction, and releases organic carbon from soil minerals, which in turn increases SOM mineralization. Gram + and fungi were involved in straw decomposition in response to biochar application and responsible for SOM mineralization.Graphical

Contrasting mechanisms of nutrient mobilization in rhizosphere hotspots driven by straw and biochar amendment

Straw return strategies are widely used green management practices that can alter soil organic matter transformation and dynamics through changes in microbial community structure and functions. How the exogenous input of organic materials of contrasting qualities affects the composition of dominant taxa, growth, and microbial functional properties related to nutrient acquisition in space remains unclear. In this study, we investigated the hotsopts and kinetics of C- and N-acquiring hydrolases, microbial growth, and bacterial community structure in maize rhizosphere hotspots after the addition of straw and straw-derived biochar using soil zymography, substrate-induced respiration and high-throughput sequencing. Compared with no amendment and maize straw-derived biochar, straw addition increased the growing biomass and microbial specific growth rate by 1.2–1.6 and 1.7–2.0-fold, respectively, indicating the relative dominance of fast-growing r-strategists. This corresponds to an increased relative abundance of the keystone taxa Firmicutes and their gene copies encoding β-1,4-glucosidase (BG) and β-N-acetylglucosaminidase (NAG). The potential activity and affinity (Vmax and Km) of BG increased 2.2 and 1.8 times, respectively, and those of NAG increased 4.0 and 2.0 times, respectively. In contrast, the relative abundance of Actinobacteria belonging to K-strategists increased in the biochar-amended soil. This resulted in slower growth and retarded enzymatic activity than the straw return treatment. Biochar enhanced the root biomass by 31% and increased the rhizosphere hotspot extents of BG and NAG by 26% and 47%, respectively. The highest robustness and modularity of the co-occurrence network indicated a more stable network with biochar input. In summary, the addition of straw accelerated rhizosphere nutrient cycling by triggering microbial growth, especially fast-growth r-strategists (Firmicutes), and synthesizing a large number of enzymes. In contrast, the addition of biochar increased rhizosphere nutrient mobilization by expanding the extent of rhizosphere hotspots to mobilize nutrients from a larger soil volume. This suggests that there are different strategies for nutrient mobilization in the rhizosphere with contrasting exogenous C addition.

Preparation of Biomass Biochar with Components of Similar Proportions and Its Methylene Blue Adsorption.

Rapeseed straw, bagasse, and walnut peel have a large amount of resource reserves, but there are few technologies for high value-added utilization. In the research of biochar, walnut green husk is rarely used as raw material. In addition, the three main components of biomass (lignin, cellulose, and hemicellulose) are present in similar proportions, and the differences between the physical and chemical properties of biochar prepared with similar amounts of biomass raw materials are not clear. Using three kinds of biomass of the same quality as raw materials, biochar was prepared via pyrolysis at 400 °C, and activated carbon was prepared via CO2 activation at 800 °C. The results showed that the pore numbers of the three kinds of biochar increased after activation, resulting in the increase of the specific surface area. The resulting numbers were 352.99 m2/g for sugarcane bagasse biochar (SBB)-CO2, 215.04 m2/g for rapeseed straw biochar (RSB)-CO2, and 15.53 m2/g for walnut green husk biochar (WGB)-CO2. Ash increased the amount of carbon formation, but a large amount of ash caused biochar to form a perforated structure and decreased the specific surface area (e.g., WGB), which affected adsorption ability. When the three main components were present in similar proportions, a high content of cellulose and lignin was beneficial to the preparation of biochar. The adsorption value of MB by biochar decreased with the increase of biomass ash content. After activation, the maximum adsorption value of MB for bagasse biochar was 178.17 mg/g, rapeseed straw biochar was 119.25 mg/g, and walnut peel biochar was 85.92 mg/g when the concentration of methene blue solution was 300 mg/L and the biochar input was 0.1 g/100 mL at room temperature. The adsorption of MB by biochar in solution occurs simultaneously with physical adsorption and chemical adsorption, with chemical adsorption being dominant. The optimal MB adsorption by SBB-CO2 was dominated by multimolecular-layer adsorption. This experiment provides a theoretical basis for the preparation of biochar and research on its applications in the future.

Nine years of low-dose biochar amendment suppresses nitrification rate in low-yield brown soil

Nitrification is the crucial process of nitrogen (N) transformation and ammonia oxidation is the first and the speed-limited step of nitrification. The one-time amendment of large quantities of biochar has been reported to alter soil fertility. However, it remains unclear how continuous low-dose biochar application affects the abundance and community composition of ammonia oxidizers and the subsequent nitrification and crop production. In this article, we calculate the soil net nitrification rate and the abundance and communities of ammonia-oxidizers across different growth stages of peanuts at 0–20 cm soil layer under four fertilization regimes, namely control with zero fertilization (CK), biochar application (BC), chemical fertilizer application (NPK) and biochar-based fertilizer application (BBF). Results showed that continuous application of low-dose biochar can significantly increase crop yield by 7.8 % compared to unfertilized soil indirectly through regulating the microbial mechanism in the nitrification process. The highest bacterial amoA gene copy numbers were found in the NPK treatment, 2.35-fold higher than the CK treatment. Compared to the single input of NPK chemical fertilizer, biochar-based fertilizer reduced the nitrification rate by reducing the relative abundance of bacteria, especially Nitrosomonas and Nitrosospira. In summary, our findings provide evidence that: (1) sustained low-dose biochar input could also increase the ammonia-oxidizing bacterial abundance, changing soil properties and increasing the crop yield; (2) biochar-based fertilizer could significantly reduce the nitrification rate compared to NPK application by reducing the AOB-amoA gene abundance and the relative abundance of Nitrosomonas and Nitrosospira; (3) soil C/N ratio was also important for the ammonia-oxidizing community.

Effects of Integrated Nutrient Management on Soil Properties, Growth and Yield of Black Gram (Vigna mungo L.) var. Shekhar-2

A field experiment was conducted at research farm of Department of Soil Science and Agricultural Chemistry, SHUATS, Prayagraj, (U.P.) on sandy loam soil to Assess the “Effects of Integrated Nutrient Management on Soil Properties, Growth and Yield of Black gram (Vigna mungo L.) var. Shekhar-2” during Zaid season of 2022. The experiment consists of nine treatment combinations, comprised in randomized block design with three replications. To achieve higher growth and yield it was found application of T9 (RDF + 100% Rhizobium + 100% Biochar) has shown effective growth under Prayagraj climatic conditions. It was observed that for physical and chemical properties of soil in treatment T9 (RDF + 100% Rhizobium + 100% Biochar) were improved significantly due to the application of Nitrogen, Phosphorus, Potassium, Rhizobium and Biochar inputs. Bulk density (Mg m-3), Particle density (Mg m-3), Pore space (%), Water holding capacity (%), pH, Electrical conductivity (dS m-1), Organic carbon (%), Available Nitrogen (kg ha-1), Available Phosphorus (kg ha-1), Available Potassium (kg ha-1). The soil organic carbon content, Water holding capacity and available NPK significantly increased in most of the treatments after harvest of Black gram, it was observed that treatment T9 (RDF + 100% Rhizobium + 100% Biochar) was best in terms of growth, yield and economic parameters with maximum plant height, the number of branches plant-1, seeds pod-1, pod yield and maximum cost benefit ratio.

Succession of bacterial community structure in response to a one-time application of biochar in barley rhizosphere and bulk soils

Biochar is often used as an amendment to enhance soil fertility by directly increasing soil pH and nutrient availability. However, biochar may also improve soil fertility indirectly by altering the succession of bacterial communities that, in turn, may alter nutrient supply and availability. To determine how biochar affects soil bacterial richness and diversity, as well as how bacterial communities respond to biochar across space and time, we studied the rhizosphere and bulk soils of potted barley plants for 2 years. Adding biochar significantly increased bacterial community richness (Chao 1 richness index) by the end of the second year in the rhizosphere (P = 0.037), but in bulk soils, we observed an increase in richness in Year 1 that dissipated by Year 2. In contrast to richness, adding biochar only had a significant effect on bacterial community diversity (Shannon diversity index) in Year 1 seedling stage (P &amp;lt; 0.001), but the effect dissipated thereafter. We also found that adding biochar increased the relative abundances of Actinobacteria and Proteobacteria but decreased the relative abundances of Acidobacteria and Chloroflexi, suggesting these communities were sensitive to biochar inputs. The biochar-sensitive genera belonging to Actinobacteria and Proteobacteria made up 45%–58% of sensitive taxa in both rhizosphere and bulk soils. Of the Proteobacteria sensitive to adding biochar, Nitrosospira and Sphingomonas were most abundant in the rhizosphere relative to bulk soils. However, despite the initial increase of biochar sensitive responders in the rhizosphere, their numbers decreased after 2 years and had 179 fewer genera than bulk soils. Our findings suggest the effect of adding biochar was relatively short-lived and that the influence of the plant phenology was a stronger driver of bacterial community change than biochar inputs 2 years after its application. Altogether, the succession of soil bacterial community structure reflected changes in the soil environment induced by the combined effect of biochar, rhizospheric inputs, and plant phenology, suggesting that changes in microbial community composition observed after amending soils with biochar, may also contribute to changes in soil fertility.

Approaches to Implementing Ecosystem Climate Projects in Russia

Russia is developing a legal framework for the Paris Agreement implementation. In Russian strategic documents, there is no consistency in measures and quantitative indicators to reduce emissions and increase absorption of greenhouse gases. The main focus on forests and other ecosystems through the implementation of climate change mitigation projects also raises questions. The purpose of this paper is to determine the goal and place of these projects within the framework of a national low-carbon policy, and to analyze the opportunities and limitations of such projects in Russia. The main criteria are the additionality, conservative baselines, and minimization of risks (leakage, non-permanence, cessation of project funding, reversion). Ecosystem projects are high-risk compared to industrial projects, while the climate component of project activities occurs only in the long-term preservation of the result. The project’s goal in Russia to refine mitigation technologies based on sustainable management of natural ecosystems: the results lead to the multiple benefits including ecosystem services of the territory, biodiversity and adaptation to climate change. Therefore, their attractiveness in the implementation of sustainable development policies of companies and the state is growing. Given the additional nature, projects will not be able to provide a significant quantitative contribution to mitigation, but can provide a tool to achieve that. At the initial stage of the Russian carbon market it is necessary to allow only reliable and transparent projects (reforestation and afforestation with mixed species; improved forest management of managed forests; management of previously unmanaged forests; restoration of wetlands/grassland ecosystems; conservation of soil carbon of agricultural lands; biochar inputs to soils). Projects such as forest conservation from logging and monoculture plantations require a separate regulatory framework to prevent tampering and minimize threats to local natural ecosystems.

Research Progress on Effects of Biochar on Soil Environment and Crop Nutrient Absorption and Utilization

As a by-product generated from the pyrolysis of biomass, biochar is extraordinary for improving the soil environment of agricultural fields, improving soil fertility, and promoting nutrient uptake and the utilization of crops. In recent years, breakthroughs in progress have been made regarding the fertility value of biochar and in investigations into the physicochemical properties of soil and into plant nutrient utilization. This review focuses on the physicochemical and biological properties of soil, on soil pollution remediation, on greenhouse gas emissions, and on the effects of biochar on the uptake and utilization of soil nutrients and plant nutrients, as well as on the preparation of biochar, and on biochar produced under different conditions. The results of the relevant studies show that the main characteristics of biochar depend on the biochemical properties and pyrolysis temperature of raw materials, which play an important role in nutrient transport and transformation in the soil. At low temperatures (≤400 ℃), the biochar prepared from manure and waste contains a large amount of nitrogen, which can be used as a nutrient source for plants. In addition, biochar enhances soil fertilizer retention by reducing soil nutrient loss, which in turn promotes nutrient uptake and utilization by crops. By controlling pyrolysis temperature and by optimizing biochar input, one can effectively reduce soil respiration, as well as reduce carbon emissions to achieve the goal of controlling carbon sources and increasing carbon sinks. Therefore, a long-term series of mapping studies on the effects of biochar application on agricultural ecosystems should be conducted, which in turn, it is hoped, will provide a theoretical reference for the physiological and ecological effects of biochar croplands.

Effect of coffee husk and cocoa pods biochar on phosphorus fixation and release processes in acid soils from West Cameroon

AbstractAcid soil in West Cameroon has limited phosphorus (P) availability which limits plant growth. This is mainly because of low pH, high levels of exchangeable aluminium (Al) and iron (Fe) and fixation of P. In this study, acid soils, sampled in Bafang, were amended with biochar produced from coffee husks (CH) and cocoa pod husks (CP) at two different temperatures (350 and 550 °C) in other to evaluate the effect on the physicochemical properties of the acid soil and the effect on P sorption and desorption. The soil was amended with biochar at a rate of 0, 20, 40 and 80 g/kg and incubated for 7 and 60 days. Physicochemical properties of all soil–biochar samples were determined followed by sorption experiments and data fitted in the Langmuir and Freundlich isotherm models in other to evaluate soil P sorption capacity and its affinity to soil amended with biochar. Moreover, desorption studies were done to evaluate the availability of P in soil amended with biochar after sorption. The outcomes of this study reveal an increase in soil pH, electrical conductivity (EC), available P, soil organic carbon and a drastic decrease in exchangeable Al and Fe. The point of zero charge of biochar‐amended soil was higher than the control and increased with amendment rate. The experimental data of the sorption of P on soils and soil–biochar samples fits into Langmuir and Freundlich models (R2 &gt; 0.9) suggesting that the P adsorption is controlled by both model mechanisms. Soil–biochar mixture results in a decrease in the sorption capacity as compared with the control and the decrease was predominant with increasing amendment rate. At amendment rates of 20, 40 and 80 g/kg after 7 days of incubation, for SCH350 were 2267, 2048 and 1823 mg/kg which increased to 2407, 2112 and 1990 mg/kg after 60 days of incubation. This tendency was observed for all biochar inputs with respect to the increase in incubation days. Furthermore, desorption of P from soil–biochar mixtures was enhanced with biochar added at greater rate and produced at higher temperature. The desorption percentage was increased by more than around 10% for all biochar types from 20 mg/kg to 80 mg/kg amendment. Thus, biochar addition to acid soils reduces P fixation to acid soil and improves P desorption to soil solution, thereby providing more available P in the soil solution and better conditions for plant growth.

Biochar affects the distribution of phosphorus in the soil profile by changing the capacity of soil to adsorb phosphorus and its distribution within soil macroaggregates

AbstractA large number of studies suggested that biochar can affect the adsorption of phosphorus (P) in soil and the distribution of P in soil aggregates, but it is still unclear whether biochar can indirectly affect the distribution of P in soil profiles through the influence of these two factors. Therefore, the ability of maize straw biochar to mitigate the risk of loss of P and improve the distribution of P in soil profile was evaluated by studying the capacity of soil to adsorb P from the soil and distribution fractions of it in diverse grain‐sized aggregates of soil. A 5‐year field trial site had received NPK fertilizer inputs at the same rate and one‐time biochar inputs at different rates (0, 15.75, 31.5 and 47.25 t ha−1) at the beginning of the experiment. Langmuir and Freundlich equations were fitted to the sorption data of the soil and suggested that the applicataion of biochar can promote P absorption capacity of soil, particularly when the rates of biochar applied were 31.5 and 47.25 t ha−1. Biochar can improve the stability of soil aggregates, and aggregates with particle sizes of 0.25–2 mm have the highest relative rate of contribution to various fractions of P in the soil. Biochar can promote the accumulation of most of the P fractions in soil aggregates, particularly when the rates of biochar applied were 31.5 and 47.25 t ha−1. The TP, Ca2‐P, Al‐P, Ca8‐P, moderately labile organic phosphorus (MLOP) and moderately resistant organic phosphorus (MROP) were primarily distributed in the 0–20 cm soil layer. Biochar increased the contents of MLOP and highly resistant organic phosphorus in the soil layer of 0–20 cm while reducing the contents of Al‐P, Fe‐P and occluded phosphorus (O‐P) in the soil layer of 0–20 cm and decreased the contents of TP, Ca8‐P, O‐P and MROP under the 20 cm soil layers. Biochar can change the distribution of P fractions along the soil profile by improving the adsorption of soil P and its distribution in the soil aggregates (0–20 cm).

Biochar and metal-tolerant bacteria in alleviating ZnO nanoparticles toxicity in barley

The constant use of zinc oxide nanoparticles (ZnO NPs) in agriculture could increase their concentration in soil, and cause a threat to sustainable crop production. The present study was designed to determine the role of spore-forming and metal-tolerant bacteria, and biochar in alleviating the toxic effects of a high dose of ZnO NPs (2000 mg kg−1) spiked to the soil (Haplic Chernozem) on barley (Hordeum sativum L). The mobile compounds of Zn in soil and their accumulation in H. sativum tissues were increased significantly. The addition of biochar (2.5% of total soil) and bacteria (1010 CFU kg−1) separately and in combination showed a favorable impact on H. sativum growth in ZnO NPs polluted soil. The application of bacteria (separately) to the contaminated soil reduced the mobility of Zn compounds by 7%, due to loosely bound Zn compounds, whereas only biochar inputs lowered Zn mobile compounds mobility by 33%, even the combined application of biochar and bacteria also suppressed the soil Zn mobile compounds. Individual application of biochar and bacteria reduced the Zn plant uptake, i.e., underground parts (roots) by 44% and 20%, and in the above-ground parts of H. sativum plants by 39% and 13%, respectively, compared to ZnO NPs polluted soil treatments. Biochar, both separately and in combination with bacteria improved the root length by 48 and 85%, and plant height by 53 and 40%, respectively, compared to the polluted control. The root length and plant height decreased by 52 and 40% in ZnO NPs spiked soil compared clean soil treatments. Anatomical results showed an improvement in the structural organization of cellular–sub–cellular tissues of root and leaf. The changes in ultrastructural organization of assimilation tissue cells were noted all treatments due to the toxic effects of ZnO NPs compared with control treatment. The results indicate that metal-tolerant bacteria and biochar could be effective as a soil amendment to reduce metal toxicity, enhance crop growth, and improve soil health.

Effects of various straw incorporation strategies on soil phosphorus fractions and transformations

AbstractReturning straw to the field is an effective method for optimizing the soil phosphorus (P) availability, in which bacteria play an important role. However, the effects of various straw incorporation strategies on P transformation between different soil P pools remain unclear. In this study, variations in soil P fractions, phosphatase activities and the abundance of phosphatase genes (phoD, phoX and phoC) as well as a P‐solubilizing gene (pqqC) at DNA (total) and cDNA (transcribed) levels were analysed in three straw incorporation treatments, including chopped straw (StrawD), straw compost (Compost) and straw‐derived biochar (Biochar), and control (no straw, CK). Compared with the CK, the moderately labile inorganic P (NaOH I‐Pi) content significantly decreased and the non‐available P (Residual P) content significantly increased in the StrawD treatment. At the same time, phosphodiesterase (PD) activity and the transcribed phoC and phoX genes as well as total pqqC gene abundance significantly increased in the StrawD treatment, suggesting that the input of chopped straw stimulated P transformations from both organic and inorganic P pools. In addition, the stable Pi (NaOH II‐Pi) content and total pqqC gene abundance in the Biochar treatment were significantly higher than that in the CK, indicating that the input of biochar increased the NaOH II‐Pi that could release available P by Pi‐solubilizing bacteria. In comparison to the CK, the Compost input significantly decreased one labile Pi (resin‐Pi) only. However, its P fractions were significantly different from that of CK, Biochar and StrawD treatments, suggesting that the effects of compost input on P should not be ignored. In conclusion, chopped straw input increased soil P transformation but not available P, biochar input may promote inorganic P transformation, and compost input has a latent effect on P transformation. The study provided a comprehensive understanding of straw incorporation strategies for regulating soil P availability.

Impact of biochar, fertilizers and cultivation type on environmentally persistent free radicals in agricultural soil.

Environmentally persistent free radicals (EPFRs) have been considered as emerging contaminants due to their detrimental effects on human health. The adverse health impacts are attributed to oxidative stress induced by EPFRs through the formation of reactive oxygen species (ROS). In soils, it may also increase the degradation process of polymeric organic matter and/or undesired organic pollutants through hydroxyl radical activity. The biochar pyrolysis process entails the thermal decomposition of organic compounds in the biomass, with the carbonization conditions and feedstock type facilitating the formation of EPFRs. When biochar is used to amend soil, these radicals may promote the formation of ROS, and thus influence the transformation of organic and inorganic contaminants in soil and impact the rhizosphere. Agricultural soils are being amended with biochar to mainly increase carbon content and facilitate the plant growing conditions. Therefore, agricultural soils may become a source of EPFRs. However, the fate and transformations of EPFRs in soils after biochar amendment are not well understood or studied. This paper presents the first (to our knowledge) studies of EPFRs behaviour in agricultural soil with different input of biochar, cultivation types and residence time period. Different cultivation types, addition of fertilisers and variation in biochar input, on the one hand, and presence of metals in soil, biochar and fertilizers, on the other hand, provide different conditions for EPFRs formation, accumulation and fate in agricultural soils. Two significant factors have been found to determine the fate of EPFRs in soil: transition metal content (particularly those in reaction available form) and cultivation level of soil. Cultivation significantly decreased presence of EPFRs, both carbon-centered and oxygen-centered, in relatively short periods of time, while metal presence (and particularly through fertilizer supplementation) increases the half-life of radicals and transforms organic matter to more oxygen-centered EPFRs. The amount of biochar addition plays a secondary role as the EPFRs content in the soils is in a longer term primarily controlled by the other two factors.

Net Carbon Balance between Priming and Replenishment of Soil Organic Carbon with Biochar Addition Regulated by N Addition Differing in Contrasting Forest Ecosystems

The replenishment and priming effect (PE) are two decisive processes that determine the carbon (C) sequestration potential of biochar. However, how increased nitrogen (N) availability affect these two processes and the consequent net C balance remains poorly understood. By collecting soils from three forest ecosystems (deciduous broad-leaf forest (DBF), evergreen coniferous forest (ECF), and evergreen broad-leaf forest (EBF)), we conducted a 365-day incubation experiment by adding 13C-labelled biochar plus five rates of inorganic N (0 to 15% N of soil total N). The -results showed that N addition significantly stimulated the early period (0–48 days) but did not affect the late period (49–365 days) of biochar decomposition. The effect of N addition on PE varied largely with the forest type and decomposition period; N addition significantly enhanced the negative PE -in both periods in DBF and at the late period in EBF, whereas it stimulated positive PE in the early period in EBF and ECF. At the end of incubation, the addition of biochar caused net C accumulation across all treatments due to the huge proportion of biochar (98.1%–98.9% of added biochar) retained in soils and the negative or neutral cumulative PE (−11.25–0.35 g C kg−1 SOC), and the magnitude of net C balance increased linearly with the N addition rate in DBF and EBF. Collectively, the results of this study indicate that biochar input can contribute to soil C sequestration and that N addition can enhance the C sequestration potential of biochar.

A synthesis of soil organic carbon mineralization in response to biochar amendment

Biochar amendment can alter native soil organic carbon (SOC) mineralization via the priming effect (PE); however, its direction, intensity, and controls over a broad geographic scale are not clear, undermining the predictions of SOC dynamics as impacted by biochar inputs. Here, we synthesized 5,720 measurements of CO2 effluxes from 329 soil samples with and without 13C/14C labeled-biochar additions to quantify the spatial patterns and temporal dynamics of the PE and assess the underlying environmental drivers. Across all data, biochar amendment has led to a slight but significant positive PE (i.e., 56 mg C kg−1 soil), with stronger PEs in natural ecosystems than in agricultural soils. Negative PE occurred in the short term (i.e., <9 days after biochar addition) and subsequently shifted to a strong positive PE (i.e., 364–966 days) and remained in an insignificant PE thereafter (i.e., >1450 days). Notably, soils from rainfed croplands had the lowest negative PE (−28.76 mg C kg−1 soil). Grass-derived biochar produced at a low pyrolysis temperature (i.e., 300–400 °C) induced the strongest positive PE (244 mg C kg−1 soil). The results of our structural equation model indicated that biochar pyrolysis temperature and soil C:N ratio had the largest negative and direct association with biochar-induced PE, whereas incubation temperature and microbial biomass C exerted the greatest positive and direct effects on the PE. Variance partitioning analyses further revealed that both biochar and soil properties together accounted for 73% of the explained variance in biochar-induced PE. Overall, these results add to our understanding of biochar-induced SOC priming as impacted by different land-use types, soils, and biochar properties. The amendment of wood-derived biochars produced at high pyrolysis temperatures (>500 °C) to rainfed croplands could serve as a promising strategy to achieve maximum soil C sequestration.

Numerical Simulation of Charging Biochar Composite Briquette to Blast Furnace

Partial replacement of coal and coke by biomass/biochar in the blast furnace (BF) ironmaking is important role to reduce CO2 emissions. In this research, numerical investigations were conducted on blast furnace (BF) operation with biochar composite briquette (BCB) charging. The BCB was with 11.1 mass% carbon, 72.7 mass% magnetite, 11.25 mass% wustite, 0.77 mass% metallic iron, and 4.67 mass% gangue, and the BCB charging ratio was from 0 to 60% Results revealed that in the BF operation with BCB charging, the BCB iron-oxide reached a full reduction, but the overall gasification degree of BCB biochar decreased with the increase of BCB charging ratio. By charging BCB, the thermal state in the upper BF was considerably altered, but it was insignificantly influenced in the lower BF. By charging BCB; ore reduction was retarded in the upper BF but was prompted near the zone with a temperature of 1173 K. Under a low BCB charging ratio, local gas utilization tended to increase in the mid BF but tended to decrease in the upper BF. Further increasing BCB charging ratio lead to a decrease in local gas utilization. To ensure BF smooth running and maximizing biochar input, the optimal BCB charging ratio was 40%. Under this condition, the BCB biochar of 89.3 kg/tHM could be completely utilized, and the BF coke rate was decreased by 92.1 kg/tHM.

Biochar Addition Alters C: N: P Stoichiometry in Moss Crust-Soil Continuum in Gurbantünggüt Desert.

The biogeochemical cycling of soil elements in ecosystems has changed under global changes, including nutrients essential for plant growth. The application of biochar can improve the utilization of soil nutrients by plants and change the stoichiometry of carbon (C), nitrogen (N), and phosphorus (P) in plants and soil. However, the response of ecological stoichiometry in a moss crust-soil continuum to local plant biochar addition in a desert ecosystem has not been comprehensively explored. Here, we conducted a four-level Seriphidium terrae-albae biochar addition experiment (CK, 0 t ha−1; T1, 3.185 t ha−1; T2, 6.37 t ha−1; T3, 12.74 t ha−1) to elucidate the influence of biochar input on C: N: P stoichiometry in moss crusts (surface) and their underlying soil (subsurface). The results showed that biochar addition significantly affected the C, N, and P both of moss crusts and their underlying soil (p < 0.001). Biochar addition increased soil C, N, and P concentrations, and the soil N content showed a monthly trend in T3. The C, N, and P concentrations of moss crusts increased with the addition levels of biochar, and the moss crust P concentrations showed an overall increasing trend by the month. Moreover, the soil and moss crust C: P and N: P ratios both increased. There was a significant correlation between moss crust C, N, and P and soil C and N. Additionally, nitrate nitrogen (NO3−N), N: P, C: P, EC, pH, soil moisture content (SMC), and N have significant effects on the C, N, and P of moss crusts in turn. This study revealed the contribution of biochar to the nutrient cycle of desert system plants and their underlying soil from the perspective of stoichiometric characteristics, which is a supplement to the theory of plant soil nutrition in desert ecosystems.

Effects of Biochar Addition on Soil Nitrogen Mineralization and Leaching Characteristics in Riparian Zone of Taihu Lake

Nitrogen mineralization in riparian soil changes the migration and utilization efficiency of nitrogen, which is closely related to the control of water eutrophication. The differences in soil properties caused by land use alter nitrogen retention and transport capacity. Therefore, the soil of three land use types (woodland, grassland, and cultivated land) in the western riparian zone of Taihu Lake were selected for research on the dynamic changes in nitrogen mineralization amount using an incubation experiment and a leaching characteristics by soil column leaching experiment, and their environmental effects were also studied under different biochar addition conditions (0%, 1%, and 5%). The results showed that, in general, the addition of biochar inhibited nitrogen mineralization in forest land and grassland soil, whereas the effect of biochar on nitrogen mineralization in cultivated land was promoted in low concentrations but inhibited in high concentrations. Leaching experiments showed that the biochar addition reduced the loss of soil mineral nitrogen, and the reduction rate in ammonia nitrogen was 23.28%-39.79%, whereas there was little difference between the three land use types. The nitrate decreased by 17.20%-44.49%, and the reduction rate of cultivated land was smaller than that of forest land and grassland. In conclusion, the input of biochar into grassland and cultivated land can better maintain soil fertility and reduce soil nitrogen loss in riparian soil.