Co-application Of Biochar Research Articles

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

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

Application of biochar and selenium together at low dose efficiently reduces mercury and methylmercury accumulation in rice grains

Irrespective of cost and ecological risk, literatures have reported that both biochar and selenium (Se) alone at high application rate exhibited positive effects on decreasing rice mercury (Hg) uptake in high Hg contaminated paddy soil. In this study, we investigated whether biochar and Se together at low dose could efficiently reduce the rice grain Hg and MeHg accumulation in the slight Hg-contaminated soil. Compared with control (CK), the Hg concentration of grains in the BC3, Se0.5, and BC3 + Se0.5 treatments decreased by 5.4 %, 38.3 %, and 48.5 %, respectively. Co-application of biochar and Se also decreased the methylmercury (MeHg) concentration in rice grains by 29.1–91.6 %. The decrease of Hg and MeHg level in rice grains for biochar and Se treatments could be attributed to the following mechanisms: (1) high Hg (primarily inorganic Hg) adsorption on biochar through its high hydroxyl groups and large specific surface area; (2) Increased dissolved organic carbon and cysteine contents in pore water after biochar application, which reduced the availability of soil Hg through complexation; (3) Decreased bioavailability of Hg in soil due to the formation of HgSe precipitation which inhibited Hg uptake and translation by rice plant; (4) Both biochar and Se facilitated the reduction of MeHg in soil. Our results indicate that co-application of biochar and Se at low dose is a promising method to effectively mitigate Hg accumulation in rice grains from the slight Hg-contaminated soil.

Enhancement of nutrient use efficiency with biochar and wood vinegar: A promising strategy for improving soil productivity.

The co-application of biochar and wood vinegar has demonstrated the potential to enhance premium crop production. The present study reveals the effects of co-applying rice husk biochar and wood vinegar (both foliar and soil application) on soil properties and the growth of Chinese cabbage (Brassica chinensis L.) in a two-season pot experiment. The soil pH, electrical conductivity and dissolved organic carbon contents in combination treatments of wood vinegar and biochar were increased more when wood vinegar was applied to soils rather than to leaves, and the parameters were observed to surpass those for chemical fertilizer treatments. The biomass of Chinese cabbage shoots was significantly increased by 60.8- and 27.3-fold in the combined treatments compared to the control when 1% wood vinegar was sprayed to the leaves (WF1) in 2022 and 2023, respectively. Higher contents of vitamin C, soluble protein and soluble sugar were also observed in the combined wood vinegar and biochar treatments compared to chemical fertilizer treatments and the control; for example, the vitamin C content of plant shoot in WF1 was 21.3 times that of the control. The yield and quality of plants were decreased across all treatments in 2023 compared to 2022 but the combination treatments still displayed superiority. The co-application of wood vinegar and biochar enhances the growth and improve the quality of Chinese cabbage through improving the soil properties and plant photosynthesis. Moreover, the foliage application of wood vinegar is more preferable compared to soil application. © 2024 Society of Chemical Industry.

The effect of combined application of biochar and phosphate fertilizers on phosphorus transformation in saline-alkali soil and its microbiological mechanism

This study investigated the effects of combining Phragmites australis-based biochar, prepared at 400 °C, with various types of phosphate fertilizers—soluble, insoluble, and organic—on the content and transformation of phosphorus fractions in saline-alkali soil. Additionally, we explored microbiological mechanisms driving these transformations. The results showed that this combination significantly increased the concentrations of dicalcium phosphate (Ca2P), octacalcium phosphate (Ca8P), aluminum phosphate (AlP), moderately labile organic phosphorus (MLOP), and resistant organic phosphorus (MROP) in soil. Conversely, the levels of hydroxyapatite (Ca10P) and highly resistant organic phosphorus (HROP) decreased. The increase in labile organic phosphorus (LOP) content or decrease in iron phosphate (FeP) was found to effectively enhance the availability of Olsen phosphorus (Olsen-P) in soil. Furthermore, the study revealed that biochar mixed with organic phosphate fertilizers increased the activity of soil acid phosphatase (ACP) and neutral phosphatase (NEP), while reducing alkaline phosphatase (ALP) activity. In contrast, biochar combined with soluble and insoluble phosphate fertilizers decreased the activity of ACP (22.59 % and 28.57 %, respectively) and NEP (62.50 % and 11.11 %, respectively), with the combination with insoluble fertilizers also reducing ALP activity by 55.84 %, whereas the soluble combination increased it by 190.34 %. Additionally, the co-application of biochar and phosphate fertilizers altered the composition and abundance of the gene phoD-harboring microbial community, enhancing the abundance of Proteobacteria and reducing that of Actinobacteria. Correlation analysis between phoD-functional microbial species and various phosphorus fractions showed that Rhodopseudomonas was significantly associated with several phosphorus components, exhibiting a positive correlation with Ca2P, Ca8P, AlP, LOP, MLOP, and MROP, but a negative relationship with Ca10P. These findings suggest that the combined application of biochar and phosphate fertilizers could change the abundance of Rhodopseudomonas, potentially influencing phosphorus cycling in the soil. This research provides a strong scientific foundation for the efficient combined use of biochar and phosphate fertilizers in managing saline-alkali soil.

Evaluating Impacts of Biochar and Inorganic Fertilizer Applications on Soil Quality and Maize Yield Using Principal Component Analysis

A 2-year field experiment was conducted to test the effects of individual and co-application of biochar and inorganic fertilizer on soil quality using the principal component analysis (PCA) technique. The dry season field experiments were performed with biochar applied at 0 and 20 t ha−1, and fertilizer at 300 and 0 kg ha−1 (control). The factorial combinations of the above-mentioned treatments were subjected to irrigation at 60, 80, and 100% of irrigation amounts (IAs). Soil hydro-physical and chemical properties and grain yield were determined at harvest. Results from the PCA indicated that the soil total nitrogen (N) and moisture content (MC) were the soil properties mostly affecting the grain yield. The amendments’ effects on the soil physico-chemical properties and maize yield were in the order control < biochar < fertilizer < biochar + fertilizer. The derived comprehensive soil quality index (CSQI) from the PCA showed that the soil quality increased by 76, 100, and 200% in treatments individually applied with biochar, inorganic fertilizer, and the co-applications. This study therefore showed that the PCA revealed the actual dynamics in soil properties, in terms of the SQI upon the soil amendment addition, as well as their relationship with maize yield under different weather conditions.

Co-application of biochar and potassium fertilizer improves soil potassium availability and microbial utilization of organic carbon: A four-year study

Biochar is a promising amendment for improving soil carbon (C) sequestration and supplying potassium (K). However, the interrelationship between soil organic carbon, potassium availability, and microbial functions under the co-application of biochar and exogenous K remains largely unknown. Therefore, we conducted a four-year experiment that involved four K fertilizer application rates (0%, 60%, 80%, and 100% of conventional K fertilizer, respectively) combined with two doses of biochar rate (0% and 2%). We utilized a combination of high-throughput sequencing and GeoChip technology to examine the microbial responses to changes in soil organic C and K pools. The results revealed that biochar had the potential to replace 40% of conventional K fertilizer. The simultaneous application of biochar and conventional K fertilizer increased soil available K content by 192.3% and enhanced citrus growth. Additionally, soil organic matter, humus components, and aromatic C groups were significantly influenced by the addition of biochar. Soil enzyme activities associated with C cycling improved by 31.9%–84.4%. Furthermore, altered microbial communities, higher bacterial diversity, and enhanced microbial carbon source utilization capacity were observed in soil treated with the combined application of biochar and K fertilizer. The improvement of soil K availability induced by the co-application of biochar and K fertilizer resulted in a 35.2% increase in the microbial functions responsible for liable C degradation. Overall, the 4-years of co-application of biochar and K fertilizer increased the availability of soil potassium and the storage of organic carbon by 2.9- and 1.8-fold, respectively, which is conducive to promoting sustainable agricultural development.

Granulation compared to co-application of biochar plus mineral fertilizer and its impacts on crop growth and nutrient leaching

Mechanized biochar field application remains challenging due to biochar’s poor flowability and bulk density. Granulation of biochar with fertilizer provides a product ready for application with well-established machinery. However, it’s unknown whether granulated biochar-based fertilizers (gBBF) are as effective as co-application of non-granulated biochar with fertilizer. Here, we compared a gBBF with a mineral compound fertilizer (control), and with a non-granulated biochar that was co-applied at a rate of 1.1 t ha−1 with the fertilizer in a white cabbage greenhouse pot trial. Half the pots received heavy rain simulation treatments to investigate nutrient leaching. Crop yields were not significantly increased by biochar without leaching compared to the control. With leaching, cabbage yield increased with gBBF and biochar-co-application by 14% (p > 0.05) and 34% (p < 0.05), respectively. Nitrogen leaching was reduced by 26–35% with both biochar amendments. Biochar significantly reduced potassium, magnesium, and sulfur leaching. Most nitrogen associated with gBBF was released during the trial and the granulated biochar regained its microporosity. Enriching fertilizers with biochar by granulation or co-application can improve crop yields and decrease nutrient leaching. While the gBBF yielded less biomass compared to biochar co-application, improved mechanized field application after granulation could facilitate the implementation of biochar application in agriculture.

Effect of biochar and inorganic fertilizer on the quality of beetroot (Beta vulgaris L.) in Kenya

Despite its health benefits, the production and quality of beetroot is still low in Kenya due to the application of non-recommended rates of fertiliser and soil amendment. This research aimed at contributing to the improvement of the beetroot quality in Kenya. It was designed to determine the effects of biochar and NPK (17-17-17) on the quality of beetroot in Kenya. An RCBD factorial experiment was conducted at Egerton University farm, Kenya, for two seasons. Biochar (0, 5, 10 t/ha) and NPK (0, 200, 300 and 400 kg/ha) were applied together before planting. Data were collected on beetroot diameter, total phenolics, total soluble solids, calcium, iron and phosphorus contents and analysed using SAS statistical software. The co-application of biochar and NPK significantly (p≤0.05) increased the beetroot diameter, iron, calcium, phosphorus, TSS and phenolics content in season two and not in season one. The sole application of biochar showed a significant increase in the iron content of beetroot in season one. However, biochar did not have a significant effect on beetroot diameter, mineral content, TSS and phenolics content of beetroot in season two. The sole application of NPK at 200, 300 and 400 kg/ha significantly (p≤0.05) increased the diameter of beetroot and iron content in both seasons one and two and also significantly improved the calcium and phosphorus content in season two. These NPK levels were not statistically different from each other, but different from the control. It is therefore recommended to apply NPK and biochar for quality beetroot.

Effect of physical and chemical co-application of biochar and sulfidated nano scale zero valent iron on the NB degradation in soil: Key roles of biochar

Sulfidated nano zero-valent iron (S-nZVI) can efficiently degrade nitrobenzene (NB) in water. However, its practical application in soil remediation is constrained by limited contact with soil-sorbed NB, leading to sparse research. Herein, Biochar (BC), with its notable adsorption capacity, was coupled with S-nZVI to assess the role of physical (S-nZVI + BC) and chemical (S-nZVI@BC) co-application of BC and S-nZVI, respectively, on enhancing NB degradation in soil. Regardless of the physical or chemical co-application, there was a remarkable advantage after addition of BC relative to S-nZVI alone. In physical co-application, the NB degradation rate of S-nZVI + BC increased as the increasing BC concentration from 0 to 3.5 g·L−1, attributed to enhanced NB desorption via the solubilization effect of BC, facilitating interaction with S-nZVI. Beyond this concentration, no significant improvement was observed, possibly due to BC obstructing reactive sites on S-nZVI surface. In chemical co-application, the S-nZVI@BC (S-nZVI/BC mass ratio of 1:1) exhibited a high NB degradation rate constant (1.097 h−1) during reaction. Apart from solubilization effect, BC in S-nZVI@BC endowed S-nZVI with a higher anti-oxidation property, hydrophobicity, electron transfer capacity, and dispersion effect, accounting for the higher reactivity of S-nZVI@BC over S-nZVI + BC. Besides, the water/soil ratio and initial soil pH significantly affected NB degradation rate, with the optimum water/soil ratio and initial soil pH being 3 and 5, respectively. Our finding broadens the applicability of BC and may offer a highly effective way in soil remediation.

Additive effects of basalt enhanced weathering and biochar co-application on carbon sequestration, soil nutrient status and plant performance in a mesocosm experiment

Co-deployment of a portfolio of carbon removal technologies is anticipated in order to remove several gigatons of carbon dioxide from the atmosphere and meet climate targets. However, co-application effects between carbon removal technologies have rarely been examined, despite multiple recent perspectives suggesting potential synergies between basalt enhanced weathering and biochar application. To study the co-application effects of basalt for enhanced weathering and biochar on carbon sequestration, along with related co-benefits and risks, we conducted a fully replicated factorial mesocosm experiment with wheat. Basalt applied alone (74 t ha−1) resulted in an estimated carbon sequestration potential of 1.13 t of equivalent CO2 ha−1 over the course of approximately 6 months. Co-application with biochar (12 t ha−1) did not significantly increase estimated carbon sequestration potential. Total alkalinity fluxes and isotopic evidence indicated nearly exactly additive effects of basalt and biochar co-applied, with no significant interaction effect. Biochar carbon sequestration, approximately 32 t of equivalent CO2 ha−1 in our experiment, was unaffected by basalt addition during our experiment. Co-benefits of basalt and biochar on plant biomass as well as nutrient uptake and availability similarly mostly showed additive tendencies when co-applied. Nonetheless, a few synergistic tendencies were observed when co-applied for plant potassium and magnesium uptake as well as soil calcium availability. Soil calcium availability increased by 126% compared to expected effects based on separate application. Finally, we did not observe a reduction in the increased uptake of potentially harmful trace elements released from basalt when co-applied with biochar. Overall, our results support the co-application of basalt for enhanced weathering and biochar, with additive effects on carbon sequestration and additive, if not synergistic, effects on associated co-benefits.

Co-applied magnesium nanoparticles and biochar modulate salinity stress via regulating yield, biochemical attribute, and fatty acid profile of Physalis alkekengi L.

While previous studies have addressed the desirable effects of biochar (BC) or magnesium nanoparticles (Mg NPs) on salinity stress individually, there is a research gap regarding their simultaneous application. Additionally, the specific mechanisms underlying the effects of BC and Mg NPs on salinity in Physalis alkekengi L. remain unclear. This study aimed to investigate the synergistic effects of BC and Mg NPs on P. alkekengi L. under salinity stress conditions. A pot experiment was conductedwith salinity at 100 and 200 mM sodium chloride (NaCl), as well as soil applied BC (4% v/v) and foliar applied Mg NPs (500 mg L-1) on physiological and biochemical properties of P. alkekengi L. The results represented that salinity, particularly 200 mM NaCl, significantly reduced plant yield (58%) and total chlorophyll (Chl, 36%), but increased superoxide dismutase (SOD, 82%) and catalase (CAT, 159%) activity relative to non-saline conditions. However, the co-application of BC and Mg NPs mitigated these negative effects and improved fruit yield, Chl, anthocyanin, and ascorbic acid. It also decreased the activity of antioxidant enzymes. Salinity also altered the fatty acid composition, increasing saturated fatty acids (SFAs) and polyunsaturated fatty acids (PUFAs), while decreasing monounsaturated fatty acids (MUFAs). The heat map analysis showed that fruit yield, anthocyanin, Chl, and CAT were sensitive to salinity. The findings can provide insights into the possibility of these amendments as sustainable strategies to mitigate salt stress and enhance plant productivity in affected areas.

Co-application of biochar and selenium nanoparticles improves yield and modifies fatty acid profile and essential oil composition of fennel (Foeniculum vulgare Mill.) under cadmium toxicity.

Fatty acids and essential oils (EOs) are the primary variables that influence the quality of fennel (Foeniculum vulgare Mill.). Soil toxicity to cadmium (Cd) is the main environmental issue facing fennel, and priming methods like soil amendments and nanoparticles (NPs) are commonly utilized to deal with it. The goal of the current study was to examine the effects of biochar (BC) and selenium nanoparticles (Se NPs) on fennel plants in Cd-contaminated soils. The pot experiment was conducted with Cd stress at 0, 10, and 20mgkg-1 soil, BC at 5% (v/v), and foliar-spraying Se NPs at 40mg L-1 as a factorial completely randomized design (CRD) at a greenhouse condition in 2022. The findings demonstrated that Cd toxicity significantly decreased plant performance, while BC and Se NPs enhanced it. Without BC and Se NPs, Cd toxicity at 20mgkg-1 soil decreased biological yield (39%), seed yield (37%), EO yield (32%), and monounsaturated fatty acids (14%), while increased saturated fatty acid (26%) and polyunsaturated fatty acids (40%) of fennel. The main EO profile was anethole (65.32-73.25%), followed by limonene (16.12-22.07%), fenchone (5.57-6.83%), and estragole (2.25-3.65%), which mainly were oxygenated monoterpenes. The combined application of BC and Se NPs improved the yield, EO production, and fatty acid profile of fennel plants under Cd stress, increasing the plants' resistance to Cd toxicity.

Synergistic effects of biochar and potassium co-application on growth, physiological attributes, and antioxidant defense mechanisms of wheat under water deficit conditions

Global wheat production faces a severe threat from drought stress, necessitating innovative strategies for enhanced crop resilience. This study examined the synergistic impact of biochar and potassium co-application on the growth, physiological attributes, and antioxidant defense system of wheat under water deficit conditions at crown root initiation (CRI), anthesis, and grain development stage. Drought-induced reactive oxygen species (ROS) accumulation, particularly pronounced at the CRI stage, adversely affected all growth stages. At CRI, co-application of biochar and foliar potassium delivered significant improvements in growth parameters, including increased plant height (15.4%), spike length (50%), grain yield (43.0%), photosynthetic performance (chlorophyll content 125.8%), and relative water content (11.2%), compared to untreated drought-exposed counterparts. The combined application of biochar and potassium effectively reduced hydrogen peroxide production, electrolyte leakage, proline accumulation, and malondialdehyde generation, while increasing relative water content and glutathione levels under both well-irrigated and drought stress conditions. Furthermore, the combined biochar and potassium treatment was effective in mitigating oxidative stress and enhancing physiological resilience in wheat, particularly during the anthesis stage of drought stress. Specifically, the combined treatment ameliorated the effects of drought by reducing ROS levels through enhanced antioxidant enzyme activities and elevating osmoprotectants levels. The synergistic modulation of tissue osmotic balance and relative water content holds promise for mitigating drought-induced stress, offering an innovative and practical strategy for resilient wheat production in water-limited environments.

Promoting nitrogen conversion in aerobic biotransformation of swine slurry with the co-application of manganese sulfate and biochar

This study aimed to explore the co-application of MnSO4 (Mn) and biochar (BC) in nitrogen conversion during the composting process. A 70-day aerobic composting was conducted using swine slurry, supplemented with different levels of Mn (0, 0.25%, and 0.5%) and 5% BC. The results demonstrated that the treatment with 0.5MnBC had the highest levels of NH4+-N (3.07 g kg−1), TKN (29.90 g kg−1), and NO3−-N (1.94 g kg−1) among all treatments. Additionally, the 0.5MnBC treatment demonstrated higher urease, protease, nitrate reductase, and nitrite reductase activities than the other treatments, with the peak values of 18.12, 6.96, 3.57, and 15.14 mg g−1 d−1, respectively. The addition of Mn2+ increased the total organic nitrogen content by 29.59%–47.82%, the acid hydrolyzed ammonia nitrogen (AN) content by 13.84%–57.86% and the amino acid nitrogen (AAN) content by 55.38%–77.83%. The richness of Chloroflexi and Ascomycota was also enhanced by the simultaneous application of BC and Mn. Structural equation modeling analysis showed that Mn2+ can promote the conversion of Hydrolyzed Unknown Nitrogen (HUN) into AAN, and there is a positive association between urease and NH4+-N according to redundancy analysis. Firmicutes, Basidiomycota, and Mortierellomycota showed significant positive correlations with ASN, AN, and NH4+-N, indicating their crucial roles in nitrogen conversion. This study sheds light on promoting nitrogen conversion in swine slurry composting through the co-application of biochar and manganese sulfate.

Performance of wood waste biochar and food waste compost in a pilot-scale sustainable drainage system for stormwater treatment

Sustainable drainage system (SuDS) for stormwater reclamation has the potential to alleviate the water scarcity and environmental pollution issues. Laboratory studies have demonstrated that the capacity of SuDS to treat stormwater can be improved by integrating biochar and compost in the filter media, whereas their performance in scaled-up applications is less reported. This study examines the effectiveness of a pilot-scale SuDS, bioswale followed by bioretention, amended with wood waste biochar (1, 2, and 4 wt.%) and food waste compost (2 and 4 wt.%) to simultaneously remove multiple pollutants including nutrients, heavy metals, and trace organics from the simulated stormwater. Our results confirmed that SuDS modified with both biochar (2 wt.%) and compost (2 wt.%) displayed superior water quality improvement. The system exhibited high removal efficiency (> 70%) for total phosphorus and major metal species including Ni, Pb, Cd, Cr, Cu, and Zn. Total suspended solids concentration was approaching the detection limit in the effluent, thereby confirming its capability to reduce turbidity and particle-associated pollutants from stormwater. Co-application of biochar and compost also moderately immobilized trace organic contaminants such as 2,4-dichlorophenoxyacetic acid, diuron, and atrazine at field-relevant concentrations. Moreover, the soil amendments amplified the activities of enzymes including β-D-cellobiosidase and urease, suggesting that the improved soil conditions and health of microbial communities could possibly increase phyto and bioremediation of contaminants accumulated in the filter media. Overall, our pilot-scale demonstration confirmed that the co-application of biochar and compost in SuDS can provide a variety of benefits for soil/plant health and water quality.

Co-application of biochar and melatonin enhances pea (Pisum sativum L.) performance and alleviates cadmium contamination stress

Co-application of biochar and melatonin enhances pea (Pisum sativum L.) performance and alleviates cadmium contamination stress

Impact of co-application of biochar and &lt;i&gt;Pseudomonas aeruginosa&lt;/i&gt; on microbial parameters in heavy metal contaminated soil

The use of biochar in remediation of heavy metal contaminated soil has gained global attention in the last decade. However, there is a need for more studies on the effects and interaction of biochar and functional microbes on the resident soil microorganisms and enzyme activities in the soil. This study, therefore investigated the effects of co-application of Adenopus breviflorus (Christmas melon) derived biochar and a heavy metal tolerant Pseudomonas aeruginosa on microbial population, bacterial diversity and enzyme activities in soil artificially spiked with cadmium, copper and lead in a pot experiment. Christmas melon seeds were collected from farms in Ago-Iwoye and subjected to pyrolysis to produce biochar which were modified with acid and base. Treatments included control, acidic biochar (BA), co-application of acidic biochar and Pseudomonas aeruginosa (BAPS), basic biochar (BB), co-application of basic biochar and Pseudomonas aeruginosa (BBPS), and Pseudomonas aeruginosa (P) alone. Microbial parameters were analyzed before and after treatments. The results obtained showed that treatments, particularly BBPS and BAPs, showed significant increases in microbial populations compared to the control. The predominant bacteria isolated were Pseudomonas spp.and Bacillus spp. Catalase and urease activities varied across treatments, with BB treatment demonstrating the highest catalase activity (94.80 ± 4.90 mgKMnO4 kg-1). Urease activity was highest in the BAPs treatment (0.410 ± 0.091 mgNH4 + kg-1 h-1).In conclusion, the co-application of biochar and Pseudomonas aeruginosa reduced heavy metals, boosted microbial populations, and increased enzyme activities in the soil. This strategy holds promise for mitigating soil contamination and promoting sustainable agriculture.

Biochar application alters soil metabolites and nitrogen cycle-related microorganisms in a soybean continuous cropping system

Biochar application is a promising practice to enhance soil fertility. However, it is unclear how field-aged biochar affects the soil metabolites and microbial communities in soybean fields. Here, the rhizosphere soil performance after amending with biochar addition rates at 0 (CK), 20 (B20), 40 (B40), and 60 t ha−1 (B60) was examined via a five-year in-situ field experiment based on a soybean continuous cropping system. Untargeted metabolomics and metagenomics analysis techniques were applied to study the regulatory mechanism of biochar on soybean growth from metabolomics and N cycle microbiology perspectives. We found that the contents of soil total N (TN), available N (Ava N), NH4+‐N, and NO3−‐N were significantly increased with biochar addition amounts by 20.0–65.7 %, 3.6–10.7 %, 29.5–57.1 %, and 24.4–46.7 %, respectively. The B20, B40, and B60 triggered 259 (236 were up-regulated and 23 were down-regulated), 236 (220 were up-regulated and 16 were down-regulated), and 299 (264 were up-regulated and 35 were down-regulated) differential metabolites, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis and topology analysis demonstrated that differential metabolites were highly enriched in seven metabolic pathways such as Oxidative phosphorylation and Benzoxazinoid biosynthesis. Moreover, ten differential metabolites were up-regulated in all three treatments with biochar. Biochar treatments decreased the Nitrospira abundance in soybean rhizosphere soil while increasing Bradyrhizobium abundance significantly in B60. Mantel test revealed that as the biochar addition rate grows, the correlation between Nitrospira and soil properties other than NO3−‐N became stronger. In conclusion, the co-application of biochar with fertilizers is a feasible and effective way to improve soil N supply, even though biochar has undergone field aging. This work offers new insights into the variations in soil metabolites and microbial communities associated with N metabolism processes under biochar addition in soybean continuous cropping soils.

Biotic and abiotic effects of manganese salt and apple branch biochar co-application on humification in the co-composting of hog manure and sawdust

This study aimed to understand the effects of using apple branch biochar (ABC) and manganese (Mn(II)) to enhance the humification process when sawdust and hog manure are being composted aerobically. Four treatments of sawdust and hog manure were established, namely, CK (no additives), ABC (5 % ABC), Mn (0.5 % MnSO4), and ABC-Mn (5 % ABC + 0.5 % MnSO4). The results from the 42-day composting showed that ABC-Mn treatment was the most effective. It increased the total organic matter reduction by 19.24 %, decreased CH4 emissions, produced a high level of humic acid (HA) (60.45 g/kg), and significantly elevated the degree of polymerization (HD) to 3.15 (P < 0.05) upon the end of the composting process. In addition, the presence of ABC abiotically reduced Mn(II) salt stress and promoted compost maturation. Spectroscopic examination revealed that ABC-Mn treatment facilitated the breakdown of polysaccharides and the production of stable, aromatized humus-like materials throughout the composting process. The addition of Mn(II) and ABC also changed the microbial community composition of the compost substrate, stimulated the activities of laccase and dehydrogenase, and raised the relative abundances of Ascomycetes, Firmicutes, Proteus, Actinomycetes, and Basidiomycetes. ABC addition accelerated the transformation of Mn(II) to reducible Mn(II) and Mn(IV), potentially enhancing the abiotic degradation of organic matter and the formation of humus-like substances through redox reactions. In conclusion, this study highlighted the biotic and abiotic effects of adding ABC and Mn(II) to accelerate humification during the co-composting of hog manure and sawdust.

Co-application of biochar and salt tolerant PGPR to improve soil quality and wheat production in a naturally saline soil

Soil salinity is a global problem that drastically reduces crop productivity. Therefore, there is a need to make saline soils productive. Plant growth promoting rhizobacteria (PGPR) and biochar have been shown to increase crop productivity and soil fertility when applied separately. However, their co-application in this regard has not been studied extensively. In this study, a biochar was co-applied with Bacillus thuringiensis or Bacillus tropicus, characterized as P-solubilizing and salt-tolerant PGPR, to wheat grown in a naturally saline soil (EC 8.12 dS m−1). Co-application of biochar with PGPR increased the number of tillers & spikes, straw yield, and 100-grain weight by 16–28.57%, 26.9–36.6%, 18–21.8%, and 34–37.9% respectively. This led to a 37% and 34% increase in grain yield in the case of co-application with B. thuringiensis and B. tropicus respectively. The higher growth and yield were thanks to better plant nutrition and mitigated salinity stress under co-application. Briefly, the co-application increased phosphorus content in grain, straw, and roots by up to 9–43%, 45–69%, and 5–21.5% respectively, which was higher than that in individual applications of biochar or any PGPR. In addition, co-application increased microbial biomass by 61–77% and soil available phosphorus by 37–53% across two PGPR. Evidently, the co-application contributed to increased P nutrition in two ways. Firstly, the biochar itself served as a source of available P. Secondly, the PGPR solubilized it more abundantly when biochar was there. As far the salinity stress, biochar, its co-application with B. thuringiensis, and with B. tropicus increased soil K+/Na+ by 36%, 72% and 44% respectively leading to 40%, 63%, and 55% higher K+/Na+ in grain, straw, and roots respectively. Overall, our results indicate that biochar and PGPR worked in tandem to substantially improve soil quality and wheat production compared to their sole applications. We conclude that co-application of salt tolerant PGPR and biochar is a more sustainable and better technology to produce wheat in a naturally saline soil compared to their sole applications.