Impact Of Biochar Research Articles

Effect of sludge biochar on methane production from anaerobic granular sludge

Biochar has been documented to enhance the performance of anaerobic digestion, a technique extensively utilized in the initial treatment of highly concentrated wastewater. However, the impact of biochar derived from sewage sludge on the digestion efficiency of anaerobic granules has not been previously explored. In this investigation, we introduced sewage sludge-derived biochar into the anaerobic digestion process, incorporating it with anaerobic granular sludge, to assess its effect on methane generation. As the pyrolysis temperature escalated, there was an increase in both the levels of heavy metals and the pH, factors that hindered methane generation from anaerobic granules. Methane generation from the established anaerobic granular sludge remained unaffected by the presence of biochar. However, concerning the free anaerobic microorganisms responsible for methane production in the solution, biochar expedited electron transfer while impeding methane production by channeling more electrons towards sulfate reduction. The outcomes of this study offer a theoretical basis for the utilization of sewage sludge-derived biochar in bioreactor technology based on granular anaerobic sludge.

The Co-Application of PGPR and Biochar Enhances the Production Capacity of Continuous Cropping Peppers in the Karst Yellow Soil Region of Southwest China

In recent years, a significant impediment to the advancement of China’s agricultural sector is the noteworthy challenge posed by diminished crop yields and quality due to ongoing continuous cropping obstacles. Numerous studies have consistently showcased the potential of plant growth-promoting rhizobacteria (PGPR) and biochar in augmenting the alleviation of continuous cropping barriers. Nevertheless, the potential of PGPR and biochar to remediate and improve continuous cropping peppers in the karst yellow soil area remains unclear. A 2-year field experiment was implemented to examine the impact of PGPR and biochar, when applied alone or in combination, on the production potential of continuous cropping peppers. The results revealed that PGPR and biochar significantly elevated the yield of fresh and dry pepper compared with TF treatment. The utilization of PGPR and biochar resulted in an augmentation of free amino acids, soluble sugar, and vitamin C content in pepper fruits, but a reduction in the nitrate content, which proved advantageous in enhancing the overall quality of peppers. Furthermore, the use of PGPR and biochar demonstrated significant benefits in enhancing NPK accumulation, fertilizer utilization, and economic efficiency. Nevertheless, the co-application of PGPR and biochar yielded significantly better results compared to their individual application. In conclusion, the utilization of PGPR and biochar demonstrated a favorable impact on the productivity and economic benefits of continuous cropping peppers. The simultaneous application of PGPR and biochar represents a promising approach to enhancing yield and improving the quality of peppers in the karst yellow soil region of Southwest China.

Research Advances in the Impacts of Biochar on the Physicochemical Properties and Microbial Communities of Saline Soils

The scientific management of salinized agricultural lands and the use of undeveloped saline lands to ensure food security have become one of the most urgent tasks nowadays. Biochar contains rich carbon (C) and functional groups, and processes high alkalinity, porosity, and specific surface area (SSA). Thus, it has been widely used as an effective organic conditioner in acidic or neutral soils to improve their fertility. However, so far, the impacts of biochar application on properities of saline soils and the underlying mechanisms remain unveiled. Therefore, in this study, we focus on the investigation of the impacts of biochar on the physical, chemical, and biological properties of saline soils. We found that biochar could: (1) decrease soil bulk density (BD), increase soil porosity, promote the formation of soil aggregation and enhance the leaching of soil salts; (2) increase the cation exchange capacity (CEC) of soil, decrease the salinity of soil through ion exchange and adsorption; (3) directly act as the nutrient supplements, indirectly adsorb water and nutrients or improve nutrient availability (e.g., soil organic carbon (SOC) turnover and sequestration, nutrient cycling); and (4) improve the structure and functioning of the soil microbial community and therefore indirectly impact the C, nitrogen (N) and phosphorus (P) cycling in soil systems. However, these impacts heavily depend on the properties, the concentration of the biochar added to the soil, and the type and location of the soil. In fact, some studies have shown that the addition of biochar in soil could even increase the salinity of saline soils. Another issue is the lack of long-term and large-scale field experiments regarding the impact of biochar addition on properties of saline soils. Therefore, future studies should focus on long-term field experiments with the combination of traditional soil analytical methods and mordern molecular techniques (e.g., high-throughput sequencing, macro-genomics, and metabolomics) to comprehensively reveal the response mechanism of physicochemical properties and microbial characteristics of saline soils to exogenous biochar. Our study can provide a scientific foundation for the practical agricultural production and ecological management of biochar.

The Fusion Impact of Compost, Biochar, and Polymer on Sandy Soil Properties and Bean Productivity

Two of the most significant issues confronting arid and semi-arid countries are soil degradation and the need to reclaim sandy soils and improve their properties to enhance the agricultural area and ensure food security. Many attempts to improve sandy soil properties have been attempted using soil amendments, but further research is needed to explore the combined impact of cost-effective amendments. To that purpose, we investigated the impact of various soil amendments, including single and combination applications of synthetic Super Absorbent Polymer (SAP), compost, and biochar, on sandy soil physiochemical characteristics and bean (Vicia faba L.) production and quality throughout three growing seasons. In a randomized complete block design with three replicates per treatment, different treatments such as control (without application), lower dose of SAP (SAP1), higher dose of SAP (SAP2), biochar, compost, SAP1 plus biochar, SAP1 plus compost, SAP2 plus biochar, SAP2 plus compost, and biochar plus compost were used. The combined treatments, such as SAP2 plus biochar (T8), SAP2 plus compost (T9), and biochar plus compost (T10), improved soil physiochemical characteristics and crop production significantly. Application of T10 decreased soil bulk density by 15%, 17%, and 13% while increasing soil available water by 10%, 6%, and 3% over the first, second, and third growing seasons, respectively, compared to untreated soil (T1). The application of treatment (T9) surpassed other treatments in terms of yield, quality, and economic return, significantly increasing the seed yield by 24%, 26%, and 27% for the first, second, and third season compared with untreated soil. The higher rate of polymer combined with compost could be considered a cost-effective soil amendment to improve sandy soil productivity in arid and semi-arid regions.

Comparison of Peat–Perlite-based and Peat–Biochar-based Substrates with Varying Rates of Calcium Silicate on Growth and Cannabinoid Production of Cannabis sativa ‘BaOx’

Growers have been searching for alternative horticultural growing media components because of their desire to use sustainable resources. Biochar is a carbon-based material that has been evaluated for use as an alternative aggregate in peat-based soilless substrates. Additionally, silicon (Si) has been examined as a beneficial element to promote plant growth and plant quality in a variety of crops. However, there has been limited research regarding the interaction of biochar as an aggregate and Si in soilless substrates. This study aimed to determine the impact of Si and biochar on plant growth and nutrient uptake for greenhouse-cultivated hemp (Cannabis sativa L.). Hemp plants were grown in one of 12 different substrate blends: with two rates of calcium silicate (CaSiO3), two aggregate types of biochar (medium or coarse) or perlite, and aggregate percentages of 85% peat + 15% aggregate and 70% peat + 30% aggregate. The cannabinoid concentration, plant height, diameter, or total plant biomass were similar across all substrate blends after 12 weeks of growth. Additionally, the use of CaSiO3 as a Si substrate amendment increased Si foliar concentrations, and the addition of biochar to peat-based mixes did not limit the Si availability for plant uptake. However, Si substrate amendments did not impact plant height, diameter, or total plant biomass. This suggests that the biochar tested during this study is suitable in peat-based substrates for C. sativa ‘BaOx’ production at rates up to 30% (by volume) in peat-based substrates with CaSiO3 amendments.

Ba-modified peanut shell biochar (PSB): preparation and adsorption of Pb(II) from water.

The impact of Ba-modified peanut shell biochar (Ba-PSB) on Pb(II) removal was studied and BaCl2 was used as a modifier. It was shown that the PSB obtained at 750 °C had the best adsorption effect, and the Ba-PSB had a larger specific surface area and a good adsorption effect on Pb(II). At pH = 5, concentration was 400 mg/L, time was 14 h, and temperature was 55 °C, the loading amount of black peanut shell biochar (BPSB), red peanut shell biochar (RPSB), Ba-BPSB, and Ba-RPSB reached 128.050, 98.217, 379.330, and 364.910 mg/g, respectively. In addition, based on the non-linear fitting, it was found that the quasi-second-order kinetic model, and isothermal model could be applied to describe Pb(II) adsorption on PSB and Ba-PSB. The adsorption behavior of PSB unmodified and modified was a spontaneous process. Moreover, chemical modification of BPSB, RPSB, Ba-BPSB, and Ba-RPSB for hindering of -COOH and -OH groups revealed 81.81, 77.08, 86.90, and 83.65% removal of Pb(II), respectively, which was due to the participation of -COOH, while 17.61, 21.70, 12.77, and 15.06% was from -OH group, respectively. The increase of cation strength (Na+, K+, Ca2+, and Mg2+) will reduce the adsorption capacity of PSB for Pb(II).

Impacts of biochar derived from oil sludge on anaerobic digestion of sewage sludge: Performance and associated mechanisms

The addition of biochar is a promising strategy to improve methane production via strengthening direct interspecies electron transfer (DIET) in anaerobic digestion (AD) field. In this study, a novel oil sludge biochar (OSBC) prepared at 500/600/700 °C was used to investigate its dosage effects on performances of sewage sludge AD. The characterization results indicated that OSBC prepared at 600 °C had highest electron accepting and donating capacity, meanwhile, it also contained moderate functional groups such as CO, which were in favor of methane production. Therefore, the highest accumulative methane yield (143.96 mL (g VS)−1) accompanying with the fast consumption of volatile fatty acids (VFAs) was achieved at dosage of 1.2 g. Additionally, the conductivity and enzyme activity (electron transport system activity and coenzyme F420) of AD with OSBC addition were also enhanced. Microbial community structures manifested that the potential syntrophic microbes including archaea Methanothrix, Methanospirillum, and bacteria Comamonas, Petrimonas and Syntrophomonas were enriched by OSBC due to its large surface area and microelement such as iron, and contributed to the improved methane production. The results suggested that OSBC exhibited excellent practical application potential in enhancing anaerobic sewage sludge treatment and biogas productivity.

Elucidating the impact of biochar with different carbon/nitrogen ratios on soil biochemical properties and rhizosphere bacterial communities of flue-cured tobacco plants.

In agriculture, biochar (BC) and nitrogen (N) fertilizers are commonly used for improving soil fertility and crop productivity. However, it remains unclear how different levels of BC and N fertilizer affect soil fertility and crop productivity. This study elucidates the impact of different application rates of BC (0, 600, and 1200 kg/ha) and N fertilizer (105 and 126 kg/ha) on biomass accumulation, soil microbial biomass of carbon (SMC) and nitrogen (SMN), and soil biochemical properties, including soil organic carbon (SOC), total nitrogen (TN), soil nitrate nitrogen (NO3--N), ammonium nitrogen (NH4+-N), urease (UE), acid phosphatase (ACP), catalase (CAT), and sucrase (SC) of tobacco plants. In addition, a high throughput amplicon sequencing technique was adopted to investigate the effect of different application rates of BC/N on rhizosphere bacterial communities of tobacco plants. The results confirm that high dosages of BC and N fertilizer (B1200N126) significantly enhance dry matter accumulation by 31.56% and 23.97% compared with control B0N105 and B0N126 under field conditions and 23.94% and 24.52% under pot experiment, respectively. The soil biochemical properties, SMC, and SMN significantly improved under the high application rate of BC and N fertilizer (B1200N126), while it negatively influenced the soil carbon/nitrogen ratio. Analysis of rhizosphere bacteriome through amplicon sequencing of 16S rRNA revealed that the structure, diversity, and composition of rhizosphere bacterial communities dramatically changed under different BC/N ratios. Proteobacteria, Bacteroidetes, Actinobacteria, Firmicutes, and Acidobacteria were highly abundant bacterial phyla in the rhizosphere of tobacco plants under different treatments. Co-occurrence network analysis displayed fewer negative correlations among rhizosphere bacterial communities under high dosages of biochar and nitrogen (B1200N126) than other treatments, which showed less competition for resources among microbes. In addition, a redundancy analysis further proved a significant positive correlation among SMC, SMN, soil biochemical properties, and high dosage of biochar and nitrogen (B1200N126). Thus, we conclude that a high dosage of BC (1200 kg/ha) under a high application rate of N fertilizer (126 kg/ha) enhances the biomass accumulation of tobacco plants by improving the soil biochemical properties and activities of rhizosphere bacterial communities.

Differential effects of cow dung and its biochar on Populus euphratica soil phosphorus effectiveness, bacterial community diversity and functional genes for phosphorus conversion.

Continuous monoculture leading to soil nutrient depletion may cause a decline in plantation productivity. Cow dung is typically used as a cheap renewable resource to improve soil nutrient status. In this study, our purpose was to compare the effects of different cow dung return methods (direct return and carbonization return) on soil microbial communities and phosphorus availability in the root zone (rhizosphere soil and non-rhizosphere soil) of P.euphratica seedlings in forest gardens and to explore possible chemical and microbial mechanisms. Field experiments were conducted. Two-year-old P.euphratica seedlings were planted in the soil together with 7.5 t hm-2 of cow dung and biochar made from the same amount of cow dung. Our findings indicated that the available phosphorus content in soil subjected to biochar treatment was considerably greater than that directly treated with cow dung, leading to an increase in the phosphorus level of both aboveground and underground components of P.euphratica seedlings. The content of Olsen-P in rhizosphere and non-rhizosphere soil increased by 134% and 110%, respectively.This was primarily a result of the direct and indirect impact of biochar on soil characteristics. Biochar increased the biodiversity of rhizosphere and non-rhizosphere soil bacteria compared with the direct return of cow dung. The Shannon diversity index of carbonized cow manure returning to field is 1.11 times and 1.10 times of that of direct cow manure returning to field and control, and the Chao1 diversity index is 1.20 times and 1.15 times of that of direct cow manure returning to field and control.Compared to the direct addition of cow dung, the addition of biochar increased the copy number of the phosphorus functional genes phoC and pqqc in the rhizosphere soil. In the biochar treatment, the abundance of the phosphate-solubilizing bacteria Sphingomonas and Lactobacillus was significantly higher than that in the other treatments, it is relative abundance was 4.83% and 2.62%, respectively, which indirectly improved soil phosphorus availability. The results indicated that different cow dung return methods may exert different effects on phosphorus availability in rhizosphere and non-rhizosphere soils via chemical and microbial pathways. These findings indicated that, compared to the direct return of cow dung, biochar return may exert a more significant impact on the availability of phosphorus in both rhizosphere and non-rhizosphere soils, as well as on the growth of P.euphratica seedlings and the microbial community.

Impact of biochars fabricated with typical feedstocks on soil environment and crop productivity: A case study with D. rubrovolvata

AbstractThis study aims to explore novel, environmentally friendly technologies for converting organic waste into biochar for land application for sustainable management. However, the impact of biochar on the soil environment and crop yield depends on the specific feedstock and its interaction with the soil. Through pot experiments, we investigated the effects of three different biochars (sawdust biochar, rice straw biochar and coconut shell biochar) on the growth of Dictyophora rubrovolvata at two different input levels (1% and 2%). It was found that contrary to expectations, high input levels of sawdust biochar had a negative impact on D. rubrovolvata yield, while rice straw biochar and coconut shell biochar increased D. rubrovolvata yield by 16.0% to 159.1% and 54.4% to 64.0%, respectively, at the two input levels. The study revealed the key role of soil factors (such as total phosphorus, nitrogen/phosphorus ratio, water holding capacity, ammonium nitrogen, nitrate nitrogen, CaCl2‐phosphorus, dissolved organic carbon and invertase activity) in affecting the growth of D. rubrovolvata. Through structural equation modelling analysis, the application of sawdust biochar resulted in a low N/P ratio, thereby limiting the growth of D. rubrovolvata, while the application of straw biochar and coconut shell biochar promoted mushroom growth by increasing sucrase activity and DOC content. The increase in D. rubrovolvata biomass and nutrient content indicated the superiority of RSBC and CSBC as soil amendments. However, further research is needed to determine the appropriate application scenarios for SDBC. The findings also show that the application of biochar can help improve soil physicochemical biological properties, thus having potential benefits in sustainable agricultural practices. Overall, this study provides insights into the potential of biochar technology in sustainable agricultural practices, its role in improving soil quality and crop productivity, and explores for the first time a new field of biochar application in D. rubrovolvata cultivation.

Ammonia-oxidizing archaea bacteria (AOB) and comammox drive the nitrification in alkaline soil under long-term biochar and N fertilizer applications

Ammonia-oxidizing archaea (AOA), bacteria (AOB) and complete ammonia oxidizers (comammox) take an essential part in soil nitrogen (N) cycling. In case of 8 years biochar and N fertilizer application, nevertheless, the comparative contribution of comammox, AOA and AOB to nitrification is unclear. Our long-term field study on alkaline soil (pHwater 8.49) investigated the impact of biochar and N fertilizer on nitrification rate and potential ammonia oxidation in terms of the soil properties, both physical and chemical, together with the abundance and diversity of AOA, AOB and comammox. The findings revealed that biochar and N fertilizer did not affect the amoA abundance of AOA but increased it in AOB and commamox clade A and clade B, but decreased the diversity of AOA and comammox. Nitrogen fertilization significantly declined the diversity of AOB. The AOB abundance was controlled mainly by pH, whereas the AOA, AOB and comammox Chao1 index were governed by soil microbial biomass carbon (MBC). Additionally, biochar increased the soil nitrification rate with or without N fertilizer, but N fertilizer decreased the soil nitrification rate and potential ammonia oxidation (with nitrite oxidation inhibited) under the same biochar application. Biochar and/or N fertilizer increased the corresponding contribution of AOA and comammox to ammonia oxidation by 143–156 % and 33–395 %, respectively, but suppressed the contribution of AOB. Although the abundance of AOA amoA was obviously greater than that of AOB and comammox, the highest contribution to ammonia oxidation was by AOB in soil not fertilized by N and by comammox in the N-fertilized soil. Our findings suggest that changes in soil properties brought about by biochar and N fertilizer addition can influence the diversity of AOA, AOB and comammox, affecting potential ammonia oxidation and the nitrification rate. The AOB and comammox make a bigger contribution to nitrification than AOA in the alkaline soil.

Biochar combined with different nitrogen fertilization rates increased crop yield and greenhouse gas emissions in a rapeseed-soybean rotation system

Biochar as agricultural soil amendment has been extensively investigated for its potential to sequester carbon, to mitigate greenhouse gases (GHGs) emissions, to enhance soil fertility and enhance crop yields. In this study, we investigated the impact of varying N fertilization rates in conjunction with biochar on soil properties, crop yield, and GHGs emissions in a rapeseed (Brassica napus L.)-soybean (Glycine max (L.) Merrill) rotation system for one year. Biochar and N fertilizer were applied following a factorial combination design of three biochar (B0: 0 t hm−2, B1: 15 t hm−2, and B2: 60 t hm−2) and three N fertilizer application rates (H: 100%, M: 75%, and L: 50% of the conventional application rates). In general, there was no significant effect of N fertilizer and its interaction with biochar application on soil water content, pH, and total carbon content, but the addition of biochar significantly increased these parameters (P < 0.05). The yield of both crops were significantly augmented by biochar up to 75% compared to using N fertilization alone, potentially due to enhanced N use efficiency. However, biochar significantly increased the cumulative N2O and CH4 emissions by as much as 2.2 times and 19 times, respectively, during the rapeseed season, thereby elevating the global warming potential (GWP) and the yield-scaled GWP. Nevertheless, the significantly increased soil carbon content following biochar addition might boost soil carbon sequestration, which could counterbalance the escalating GWP induced by GHGs. Therefore, we recommend a comprehensive and long-term evaluation of biochar's impact by considering crop yield, GHGs emissions, and carbon sequestration in agricultural systems to ensure sustainable agricultural management.

Contrasted effects of biochar application on interrill erosion depending on age, application rate and soil type

Besides its carbon sequestration potential, biochar can mitigate soil erosion through improved soil structure. However, the short-term erosion mitigation potential of biochar remains debated, while it is unknown in the long-term. The aim of this study was therefore to determine the impact of biochar application on soil interrill erosion parameters, and to assess whether this impact depends on biochar age and application rate for two different soils. To assess the short-term impact, experiments were performed with topsoil from cultivated silt loam and sandy loam soils enriched with fresh biochar at rates of 1% w/w (13.5 T ha−1) and 2% w/w (27 T ha−1). In the same fields, soil from former kiln sites containing 19th century-old biochar was used to assess the long-term impact. Aggregate stability was measured according to Le Bissonnais (1996). Runoff and soil loss were measured in a flume under simulated rainfall. On the sandy loam soil, old biochar and 2% fresh biochar improved aggregate resistance to slaking. For the same soil, old biochar increased the time to runoff by 55%. For both study sites together, old biochar reduced the final runoff rate by 48%, whereas 2% fresh biochar reduced the final soil loss rate by 39%. Overall, the positive impact of biochar on interrill erosion was clearly more pronounced for the sandy loam soil compared to the silt loam soil. These contrasted results call for further studies across a wider variety of soil types.

Impact of Biochar on Fusarium Wilt of Cotton and the Dynamics of Soil Microbial Community

The effects of biochar on leaf and soil-borne diseases of plants can be seen in addition to its ability to sequester carbon, improve soil quality, and enhance plant performance. However, the mechanisms by which soil-borne pathogens are suppressed and plant performance is enhanced are not well understood. The present work aims to comprehensively establish the links between biochar-induced changes in the richness of the rhizosphere microbial population, in association with the reduction of soil-borne Fusarium wilt disease (Fusarium oxysporum f. sp. vasinfectum), in cotton (Gossypium hirsutum), with improved plant performance. Biochar made from organic waste significantly decreased the colonization and survival of Fusarium in soil, raised the culture-able counts of numerous microbes with biocontrol potential (microorganisms that boost plant growth and development), and inhibited Fusarium wilt of cotton. The biochar amendment significantly enhanced the cotton plant development and physiological parameters such as chlorophyll content, etc. Overall, 9% organic waste biochar had shown a significant impact on cotton growth as compared to other treatments with or without biochar. Compared to the soil-only control, the disease index was considerably reduced in all biochar-amended treatments. In terms of the plant’s resistance to Fusarium wilt, biochar-induced increases in the level of overall chlorophyll content and biochemicals such as phenolics, flavonoids, etc. Additionally, cotton plants grown with a 9% biochar composition had considerably greater NPK levels than other treatments with or without biochar. The biochar addition resulted in increased counts of Pseudomonas spp., Actinomycetes spp., and Trichoderma spp., while Acidobacteriales, Rhodospirillales, and Frankiales were less when compared with an un-amended (without biochar) soil control. Thus, the composition of rhizosphere bacteria in the treatments with and without modified biochar was found to differ significantly.

Effects of Biochar on Drought Tolerance of Pinus banksiana Seedlings

Drought is a major stressor of tree seedlings regarding both natural and artificial regeneration, especially in excessively drained, sandy outwash soils. While climate change is expected to cause an increase in the total annual precipitation in the Upper Midwest, USA, the timing of the precipitation is predicted to result in longer periods of drought during the growing season. Biochar, a material created through the pyrolysis of organic matter, such as wood waste, has been proposed as a soil amendment that may increase the water holding capacity of a soil. Biochar has mostly been studied in agricultural settings, and less is known about the impact of biochar on forest soils and tree seedlings. We used a greenhouse experiment to test the ability of biochar to improve the drought tolerance of jack pine (Pinus banksiana) seedlings via increased soil water holding capacity. The seedlings were planted in sandy soil treated with three levels of biochar (none, 3% by weight, and 6% by weight) in two experiments, one manipulating the timing of drought onset and the other controlling the amount of water that seedlings received. Our results showed no significant effects of biochar on seedling survival, growth, or physiology under drought conditions. While this outcome did not support the hypothesis that biochar would increase seedling performance, the biochar amendments did not negatively affect seedlings, indicating that biochar may be added to soil for carbon storage without having negative short-term impacts on tree seedlings.

Contribution of biochar application to the promotion of circular economy in agriculture

The traditional linear model in agriculture based on the so-called ‘take-make-waste’ has created many problems such as resource scarcity, waste generation, climate change and biodiversity loss. Recently, with the increase in public awareness, the attentiveness in developing a circular economy model was doubled with a focus on proper waste management to bring some benefits to the agricultural sector. Although the increasing acceptance of biochar as a carbon-based material capable of playing a multidimensional role in reducing waste, mitigating climate change, and creating a closed-loop agricultural system, it is still far to move to a final conclusion that biochar application in agriculture could bring attractive environmental and economic benefits. Research conducted so far has led to many insights into how to enhance agricultural sustainability through biochar application, as the impact of biochar is strongly interrelated to their inherent properties, which vary deeply with the nature of biomass and the preparation conditions. In the present study, a systematic literature review was performed to investigate the state- of-the-art research related to the application of biochar in agriculture and its contribution in the establishment of circular economy concept. The interlinking between biochar application in agriculture with energy-water systems and its contribution to successfully build up a circular economy model has also been investigated.

Biochar improves the growth and physiological traits of alfalfa, amaranth and maize grown under salt stress.

Salinity is a main factor in decreasing seed germination, plant growth and yield. Salinity stress is a major problem for economic crops, as it can reduce crop yields and quality. Salinity stress occurs when the soil or water in which a crop is grown has a high salt content. Biochar improve plant growth and physiological traits under salt stress. The aim of the present study, the impact of biochar on growth, root morphological traits and physiological properties of alfalfa, amaranth and maize and soil enzyme activities under saline sands. We studied the impact of biochar on plant growth and the physiological properties of alfalfa, amaranth and maize under salt stress conditions. After 40 days, plant growth parameters (plant height, shoot and root fresh weights), root morphological traits and physiological properties were measured. Soil nutrients such as the P, K and total N contents in soil and soil enzyme activities were analyzed. The results showed that the maize, alfalfa, and amaranth under biochar treatments significantly enhanced the plant height and root morphological traits over the control. The biochar on significantly increased the total root length, root diameter, and root volume. Compared to the control, the biochar significantly increased the chlorophyll a and b content, total chlorophyll and carotenoid content under salt stress. Furthermore, the biochar significantly increased enzyme activities of soil under salt stress in the three crops. Biochar treatments promote plant growth and physiological traits of alfalfa, amaranth, and maize under the salt stress condition. Overall, biochar is an effective way to mitigate salinity stress in crops. It can help to reduce the amount of salt in the soil, improve the soil structure, and increase the availability of essential nutrients, which can all help to improve crop yields.

“ Assessing the impact of biochar on microbes in acidic soils: Alleviating the toxicity of aluminum and acidity”

In arable soils, anthropogenic activities such as fertilizer applications have intensified soil acidification in recent years. This has resulted in frequent environmental problems such as aluminum (Al) and H+ stress, which negatively impact crop yields and quality in acidic soils. Biochar, as a promising soil conditioner, has attracted much attention globally. The present study was conducted in a greenhouse by setting up 2% biochar rate to investigate how biochar relieves Al3+ hazards in acidic soil by affecting soil quality, soil environment, and soil microbiomes. The addition of biochar significantly improved soil fertility and enzyme activities, which were attributed to its ability to enhance the utilization of soil carbon sources by influencing the activity of soil microorganisms. Moreover, the Al3+ contents were significantly decreased by 66.61–88.83% compared to the C0 level (without biochar treatment). In particular, the results of the 27Al NMR suggested that forms of AlVI (Al(OH)2+, Al(OH)+ 2, and Al3+) were increased by 88.69–100.44% on the surface of biochar, reducing the Al3+ stress on soil health. The combination of biochar and nitrogen (N) fertilizer contributed to the augmentation of bacterial diversity. The application of biochar and N fertilizer increased the relative abundance of the majority of bacterial species. Additionally, the application of biochar and N fertilizer had a significant impact on soil microbial metabolism, specifically in the biosynthesis of secondary metabolites (lipids and organic acids) and carbon metabolic ability. In conclusion, biochar can enhance soil microbial activity and improve the overall health of acidic soil by driving microbial metabolism. This study offers both theoretical and technical guidance for enhancing biochar in acidified soil and promoting sustainable development in farmland production.

Enhancing Soil Nitrogen Retention Capacity by Biochar Incorporation in the Acidic Soil of Pomelo Orchards: The Crucial Role of pH

Biochar is commonly used to improve acidic soil and reduce nitrogen loss. However, the impact of biochar on soil nitrogen retention, especially at varying pH levels, is not fully understood. Soil samples were obtained from an acidic red soil citrus orchard. The soil pH was adjusted using CaO, with five levels (4.0, 5.1, 5.8, 6.6, and 7.2), and two biochar doses (0% and 1%) were applied. The study used 15N-Tracer and Ntrace to investigate biochar’s influence on soil nitrogen retention at different pH levels. The results showed that soil amendment with biochar improved gross mineralization rates (TM) and gross NH4+ immobilization rates (TI), except at pH 4.0 for TI. Biochar enhanced heterotrophic nitrification (ONrec) within pH 4.0–7.4, with a threshold for autotrophic nitrification (ONH4) at pH 6.4. The findings revealed biochar’s positive effect on soil nitrogen retention within pH 4.5–6.4. Biochar had a greater impact on TI than TM and inhibited ONH4, potentially enhancing nitrogen retention in this pH range. These results highlight the significance of considering biochar incorporation for improving nitrogen use efficiency and reducing NO3−-N loss in subtropical pomelo orchards.

Combining chemical and organic treatments enhances remediation performance and soil health in saline-sodic soils

We investigated the individual and synergistic impact of gypsum, elemental sulfur, vermicompost, biochar, and microbial inoculation on soil health improvement in degrading calcareous saline-sodic soils. We developed Linear and nonlinear soil health quantification frameworks to assess the efficacy of remedial practices. The combined inoculated chemical and organic treatments; gypsum + vermicompost and elemental sulfur + vermicompost with 134% (0.29 versus 0.68) and 116% (0.29 versus 0.62) increases in nonlinear index, significantly increased the efficacy of amendments compared with control. An increase in the overall soil health index ranged between 12 to 134%. Microbial inoculation further enhanced the impact of treatments on soil health. Soil health properties included in the indexes explained 29 to 87% of the variance in wheat growth. The findings bring insight into the cost-effective and environmentally sustainable practices to recover degraded saline-sodic soils. Furthermore, the introduced soil health indexes offer a quantitative evaluation of soil remediation strategies.