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This study investigates the growth dynamics and heavy metal immobilization in Sudan grass cultivated on substrates composed of electrolytic manganese residue (EMR), phosphogypsum, and chili straw biochar. Pot experiments revealed that a substrate with phosphogypsum constituting 75% of the mix hinders Sudan grass seed germination. Compared with sole EMR utilization, the composite substrates notably enhanced plant growth, evidenced by increases in plant height and fresh weight. The integration of these substrates led to a significant elevation in total chlorophyll content (up to 54.39%) and a reduction in malondialdehyde (MDA) levels (up to 21.66%), indicating improved photosynthetic activity and lower oxidative stress. The addition of biochar reduced the content of Zn, Cd, and Mn in the roots of Sudan grass by up to 25.92%, 20.00%, and 43.17%, respectively; and reduced the content of Pb, Mn, and Cr in the shoot by up to 33.72%, 17.53%, and 26.32%, respectively. Fuzzy membership function analysis identified the optimal substrate composition as 75% EMR and 25% phosphogypsum, with 5% chili straw biochar, based on overall performance metrics. This study adopts the concept of "to treat waste with waste". The approach is to fully consider the fertility characteristics of EMR, phosphogypsum, and biochar, underscoring the potential for utilizing waste-derived materials in cultivating Sudan grass and offering a sustainable approach to plant growth and heavy metal management. [ABSTRACT FROM AUTHOR]

Objective: In this study, we aimed to investigate the effects of facile combinations of biochar and N, P, and K fertilisers on the growth and physiological characteristics of Lithocarpus litseifolius seedlings, and to optimise the biochar/NPK ratio of Lithocarpus litseifolius. Method: A four-factor three-level orthogonal method was used to conduct a field experiment using 2-year-old Lithocarpus litseifolius. Nine fertiliser treatments and one control treatment (CK, i.e., no fertiliser) were established in a completely randomised block group with six replications of ten treatments. The plants were planted in October 2020 and harvested in November 2021, and fertiliser was applied once in April 2021 and once in July 2021. Results: Rational application could effectively promote the growth of Lithocarpus litseifolius, and T4(C2N1P2K3) produced the highest increase in plant height growth (17.03 cm), diameter growth (5.47 mm), soluble sugar (94.60 mg/g), soluble protein (4.59 mg/g), and phlorizin (old leaf: 16.00%; tender leaf: 15.13%); T8(C3N2P1K3) resulted in the highest chlorophyll a content (1.46 mg/g), chlorophyll b content (0.62 mg/g), and total chlorophyll content (2.08 mg/g), and T1(C1N1P1K1) resulted in the highest contents of starch (11.60 mg/g) and trilobatin (old leaf: 0.29%; tender leaf: 2.28%). The indicators corresponding to the above three treatments were significantly higher than those under the other treatments (p < 0.05). The results as analysed by the affiliation function method show that the highest mean value of the affiliation function was 0.645 after T4(C2N1P2K3) treatment. Conclusions: The combination of biochar and nitrogen, phosphorus, and potassium fertilisers can effectively increase the biomass and active components of Lithocarpus litseifolius while reducing the amount of chemical fertiliser applied. A comprehensive analysis of the results showed that the T4 treatment (biochar: 20 g/plant; urea: 10 g/plant; superphosphate: 9 g/plant; potassium chloride: 12 g/plant) resulted in the highest comprehensive score, with the highest increase in plant height growth, ground diameter growth, root–crown ratio, soluble sugar, soluble protein, and phlorizin, as well as other indicators. [ABSTRACT FROM AUTHOR]

Soil degradation due to loss of soil organic carbon is a serious concern in semiarid agroecosystems. Biochar and other organic char products have long been known to increase soil organic carbon. In this study, three-year field observations were carried out on use of coal char (CC) and biochar (BC) as soil amendments in unirrigated semiarid rangeland soil. Coal was pyrolyzed at three different temperatures of 650, 750, and 800 °C to form CC650, CC750, and CC800, respectively, and BC was obtained from a local commercial producer. Manure, CC, and BC were incorporated in soil at 10% (v/v). Analyses of plant growth (aboveground biomass) and soil properties were performed and compared with the control treatment without char. In all three years, CC applied with manure (CC650M) produced significantly greater grass biomass, by 95, 42, 101%, and BC applied with manure (BCM) increased grass biomass by 89, 39, 52% in 2018, 2019, and 2020, than the controls in the respective years. Soil tests a year after application of char indicated significantly increased soil organic matter (OM) with CC and BC treatments (1.60–2.93%) compared with the control (1.37%). However, further detailed studies are required to investigate CC and BC interactions with soil in unirrigated semiarid rangelands. [ABSTRACT FROM AUTHOR]

Decades of intensive use of copper-based fungicides against downy mildew in hops has led to considerable accumulation of copper in topsoil, resulting in toxic effects on plants. Due to its high sorption capacity, the application of co-composted biochar compost might reduce copper toxicity, whereby a synergistic effect of the composting process is supposed to occur. Furthermore, biochar addition might improve the composting process itself. Therefore, hop bines were co-composted without as well as with 5 and 20 vol% biochar, respectively. During composting, the temperature and concentration of O2, CO2, H2S, CH4 and NH3 in the compost heaps were regularly recorded. The biochar-free compost as well as the two composts with the biochar addition were characterized with regard to their plant-growing properties and were mixed into soils artificially spiked with different amounts of copper as well as into copper-polluted hop garden and apple orchard soils. The respective soil without the compost addition was used as the control, and further treatments with biochar alone and in combination with biochar-free compost were included in a plant response test with Chinese cabbage. The biochar addition increased the temperature within the compost heaps by about 30 °C and extended the duration of the thermophilic phase by almost 30 days, resulting in a higher degree of hygienization. Furthermore, the application of co-composted biochar composts significantly improved plant biomass by up to 148% and reduced the copper concentration, especially of roots, by up to 35%. However, no significant differences in the biochar-free compost were found in the artificially copper-spiked soils, and the effect of co-composted biochar compost did not differ from the effect of biochar alone and in combination with biochar-free compost. Nevertheless, the co-composting of hop bines with biochar is recommended to benefit from the positive side effect of improved sanitization in addition to reducing copper toxicity. [ABSTRACT FROM AUTHOR]

This study investigates the growth dynamics and heavy metal immobilization in Sudan grass cultivated on substrates composed of electrolytic manganese residue (EMR), phosphogypsum, and chili straw biochar. Pot experiments revealed that a substrate with phosphogypsum constituting 75% of the mix hinders Sudan grass seed germination. Compared with sole EMR utilization, the composite substrates notably enhanced plant growth, evidenced by increases in plant height and fresh weight. The integration of these substrates led to a significant elevation in total chlorophyll content (up to 54.39%) and a reduction in malondialdehyde (MDA) levels (up to 21.66%), indicating improved photosynthetic activity and lower oxidative stress. The addition of biochar reduced the content of Zn, Cd, and Mn in the roots of Sudan grass by up to 25.92%, 20.00%, and 43.17%, respectively; and reduced the content of Pb, Mn, and Cr in the shoot by up to 33.72%, 17.53%, and 26.32%, respectively. Fuzzy membership function analysis identified the optimal substrate composition as 75% EMR and 25% phosphogypsum, with 5% chili straw biochar, based on overall performance metrics. This study adopts the concept of “to treat waste with waste”. The approach is to fully consider the fertility characteristics of EMR, phosphogypsum, and biochar, underscoring the potential for utilizing waste-derived materials in cultivating Sudan grass and offering a sustainable approach to plant growth and heavy metal management.

Soil degradation due to loss of soil organic carbon is a serious concern in semiarid agroecosystems. Biochar and other organic char products have long been known to increase soil organic carbon. In this study, three-year field observations were carried out on use of coal char (CC) and biochar (BC) as soil amendments in unirrigated semiarid rangeland soil. Coal was pyrolyzed at three different temperatures of 650, 750, and 800 °C to form CC650, CC750, and CC800, respectively, and BC was obtained from a local commercial producer. Manure, CC, and BC were incorporated in soil at 10% (v/v). Analyses of plant growth (aboveground biomass) and soil properties were performed and compared with the control treatment without char. In all three years, CC applied with manure (CC650M) produced significantly greater grass biomass, by 95, 42, 101%, and BC applied with manure (BCM) increased grass biomass by 89, 39, 52% in 2018, 2019, and 2020, than the controls in the respective years. Soil tests a year after application of char indicated significantly increased soil organic matter (OM) with CC and BC treatments (1.60–2.93%) compared with the control (1.37%). However, further detailed studies are required to investigate CC and BC interactions with soil in unirrigated semiarid rangelands.

Pyrolyzed waste biomass, or biochar, has been suggested as a means to increase plant growth and mitigate soil salinization, which is a widespread agricultural issue and can reach extreme levels in urban soils impacted by de-icing salts. Soil mixing is enhanced by reduced biochar particle size; however, biochar properties vary with particle size, and recent studies have suggested that plant growth responses may be maximized at intermediate particle sizes. We examined the responses of two plant species (cowpea (Vigna unguiculata) and velvetleaf (Abutilon theophrasti)) to biochar amendments that spanned a wide range of particle sizes obtained by sieving, with and without de-icing salt additions. The smallest size fractions of biochar reduced plant growth relative to unamended controls. Plant biomass production was generally maximized at intermediate biochar particle size treatments, with particle sizes of 0.5–2.0 mm showing the best response. Mitigation of salt effects was also improved at intermediate biochar particle sizes in this particle size range. Our results emphasize the importance of optimizing biochar particle size to best enhance plant responses to biochar, with particular reference to saline soils. [ABSTRACT FROM AUTHOR]

The conversion of bio-wastes to useful products such as biochar provide a suitable option not only to minimize the mass of wastes, but also to use the biochar as soil amendment. In the present study, food waste biochar (FWB) and agricultural waste derived biochar (AB), either alone or in combination (FWB + AB), were tested for their effects on soil microbiological characteristics (soil enzymes, soil basal as well as substrate-induced respiration), plant growth and photosynthetic parameters. Four treatments were tested: control, FWB, AB and FWB + AB. The results indicated that the application of AB significantly enhanced the plant above ground and below ground fresh and dry biomass as compared to other amendments and control (+41 to +205% compared to control). The application of FWB enhanced the quantum yield of photosystem II (QY-max, +4% compared to control) and normalized difference vegetation index (NDVI, +13% compared to control). Moreover, the FWB application improved the soil dehydrogenase (DHA) activity (+24% compared to control). Furthermore, the soil basal respiration was found to be increased under AB application (+46% compared to control) and the substrate-induced respirations were relatively decreased, depicting negative effects of applied biochars on substrate-induced respirations. Thus, we concluded that the differential responses of observed crop and soil attributes might be related to the biochar specific effects on soil properties. [ABSTRACT FROM AUTHOR]

From the perspective of sustainable agri-food production, farmers need to make the best use of natural resources. Biochar can be a solution to adopt a more sustainable way of farming. Despite its environmental and agronomic advantages, biochar has a low plant nutrient value. This study evaluated the effect of biochar and the co-application of an inorganic or organic fertilizer on the soil properties, growth and nutrient content of Swiss chard (Beta vulgaris L. var. cycla, Caryophyllales order, Chenopodiaceae family). The experiment consisted of two factors: biochar type (from vineyard prunings and wood chips) and fertilizing source (ammonium nitrate and vermicompost). Biochars were applied at a 2% rate (w/w) and fertilizers at a dose providing 280 kg N ha−1. The soil properties (pH, EC, extractable anions, cations, total N, Corg and C/N ratio) were measured before the plants were transplanted and at the end of the growing cycle, along with the growth parameters (leaf number, length and fresh weight) of each leaf cut, the productive parameters (total number of leaves and yield per plant) at the end of the growing cycle and the leaf content of anions (NO3−, P2O43−, SO42−), cations (NH4+, Na+, K+, Ca2+, Mg2+) and total N. The co-application of biochar and a fertilizing source had a positive effect on soil properties and leaf nutrient content. Vermicompost increased plant growth by 22% and plant yield by 116%, in contrast to biochar, and increased limited leaf NO3− accumulation by about 81% in comparison to ammonium nitrate. The co-application of biochar and vermicompost is the better option to increase Swiss chard yield while preserving the nutritional and health qualities of the product. [ABSTRACT FROM AUTHOR]

Abiotic stresses are the most significant factors reducing agricultural productivity. Plants face extreme environmental conditions that may affect their biological mechanisms, thereby influencing their growth and development. Microorganisms possess substantial metabolites that aid in helping plants mitigate abiotic stresses. Plants' interaction with microbes constitutes a diversified ecosystem, as sometimes both the partners share a mutualistic relationship. Endophytes, plant-growth-promoting rhizobacteria (PGPRs), and arbuscular mycorrhizal fungi (AMFs) are examples of microorganisms that play an essential role in alleviating abiotic stresses and, hence, improving plant growth. The plant–microbe interaction leads to the modulation of complex mechanisms in the plant cellular system. Moreover, the residing microbial flora also inhibits the phytopathogens, therefore, it becomes part of plants' innate defense system. Keeping in view the growing environmental concerns, it is important to identify the role of the plant microbiome in the transportation of nutrients to maintain sustainable production. Furthermore, it is important to identify the factors enabling plants to recruit beneficial microbial species and how to deal with the potential pathogens. Therefore, this review aims to summarize the impacts of various abiotic stressors on agricultural productivity and the role of beneficial microorganisms in mitigating the negative effects of abiotic stresses. The literature review also shows that the beneficial microbes, including PGPRs, AMFs, and endophytes, adopt various mechanisms for ameliorating the negative effects of various stresses. It has been observed that biochar and microbes, either individually or in combination, can play a significant role in maintaining plant growth under stress conditions. Although conventional inoculation of beneficial microbes mitigates abiotic stresses and enhances productivity, the advancement in genetic engineering would help transfer specific genes from the microbes to plants to aid in abiotic stress mitigation. [ABSTRACT FROM AUTHOR]

Biochar represents a stable form of carbon-rich organic material produced by the pyrolysis of various biomass residues. It has the potential to stabilize organic carbon in the soil and improve soil fertility, water retention, and enhance plant growth. Despite its potential, there is limited information on the mutual relation of biochar texture with its physicochemical characteristics, morphology, and the content of organic matter. For these reasons, we studied three biochar samples with potential use in agriculture as soil supplements (NovoCarbo, Sonnenerde, Biouhel.cz). Our experimental approach performed on the individual sieved fraction of studied biochars (<0.5; 0.5–2.0; 2.0–4.0 and >4.0 mm) confirmed the importance of a selection of optimal source biomass material as the content of lignin, cellulose, and hemicellulose, together with the conditions of pyrolysis (temperature of pyrolysis), play a crucial role in the managing of the properties of produced biochar. Agronomically more stable biochars containing a higher content of organic matter and organic carbon, with alkaline pH response and well-developed aromatic porous structure, could be produced from lignin-based biomass residues at higher pyrolysis temperatures, which is an important finding taking into account the possible utilization of biochar in soils as a soil conditioner. [ABSTRACT FROM AUTHOR]

A serious acidification trend currently affects paddy soil and soil phosphorus (P) availability has declined in rice production. This study investigated the effect of rice-straw biochar on P availability and the adaptability of rice roots in acidified soil. Rice was grown in rhizoboxes, allowing for the precise sampling of rhizosphere and bulk soil for the sequential extraction of P fractions. Biochar may provide a liming effect and strong nutrient adsorption, leading to soil improvement. The results confirmed that biochar application significantly improved plant growth and P accumulation in shoots by 29% and 75%, respectively. However, the application of washed biochar and equivalent lime only increased shoot biomass and P accumulation by 13.4% and 11.2%, and by 42% and 38%, respectively. Compared with the control, applying biochar increased the plant-available P component contents in rhizosphere and bulk soil. Biochar affected the chemical balance among the different P fractions, increased aluminum-bound phosphate (Al-P) pool, calcium-bound phosphate (Ca-P) pool and decreased the occluded phosphate pool in acidic paddy soil. Biochar amendment significantly improved root growth of and increased the citrate exudation from roots under low P supply, accompanied by the enhanced expression of the anion-transporter-related OsFRDL4 gene and the OsPT1 phosphate transporter. The results showed that biochar application in degraded acidic soils could improve rice potential for P acquisition to increase available P component and maintain high citrate exudation. [ABSTRACT FROM AUTHOR]

The objective of this study was to explore the effects of plant growth-promoting rhizobacteria (PGPR), strain Bacillus licheniformis, with softwood biochar amendment on potato growth and water use efficiency (WUE) under a deficit irrigation (DI) regime. A pot experiment was conducted in a greenhouse. The results showed that PGPR improved leaf gas exchange rates, including photosynthesis rate, stomatal conductance and transpiration rate at early seedling stage, while tended to depress these parameters gradually until final harvest. The effects of biochar on plant leaf physiology, plant growth and WUE were not evident. Plants were more affected by DI than PGPR inoculation and biochar amendment. DI significantly decreased leaf gas exchange rates after exposure to water treatment for around three weeks, and the negative effect was eliminated at final harvest. At final harvest, DI significantly decreased leaf area, specific leaf area, dry mass of leaf and stem, total dry mass, dry mass increment and plant water use. The synergistical effect of PGPR strain Bacillus licheniformis and DI on plant growth and WUE were not observed in our study. WUE was solely improved by DI, indicating that, compared to PGPR inoculation, DI was a more effective measure to enhance plant WUE. [ABSTRACT FROM AUTHOR]

Recently, biochar has been proposed for various agronomic applications including improved plant growth and soil fertility. In this study, the effects of dairy effluent-saturated (SBC) and unsaturated wood-derived biochar (UBC) on Bermudagrass (Cynodon spp.) growth, soil fertility and microbial communities were investigated in a greenhouse pot study. SBC and UBC were mixed with sandy loam soil at various loading rates (0, 1, 2, 4, and 8%) to grow Bermudagrass for 10 weeks. Soil physicochemical properties and plant growth measurements were taken, followed by 16S rRNA (V3-V4) amplicon sequencing of soil bacterial communities. Amendment of SBC to soil altered the soil physicochemical properties and increased the concentrations of N and P in the soil at 2 to 8% loading rates compared to UBC treated soil. The addition of SBC to soil also increased the overall plant biomass compared to UBC with more effects on aboveground biomass. Differential abundance analysis of taxa showed enrichment of Proteobacteria in UBC-amended soil, whereas Firmicutes and Nitrospirae were abundant in SBC-amended soil. Interestingly, enrichment of photosynthetic and N-fixing bacteria was observed in both SBC and UBC-amended soils after 10 weeks of treatments. However, oxidative phosphorylation and biotin metabolisms were found to be more abundant in SBC-amended soil compared to UBC-amended soil. Overall, our study suggested that amendment of SBC to soil resulted in enhanced soil nutrients, microbial capacity and Bermudagrass growth than that of UBC. Therefore, application of SBC to soil in field trials would be merited to identify sustainable and effective practices for enhancing plant growth, soil fertility and soil bacterial community.

Selenium biofortification of lettuce plants was studied for two rates (5 and 10 mg kg−1 soil) of either selenate or selenite and for the effect of 5% w/w biochar addition. Lettuce seedlings were grown in pots containing 1 kg of a calcareous soil. Twelve weeks later, the plants were harvested and selenium (Se), phosphorus (P), and sulfur (S) concentrations were determined in heads and roots. Plant growth characteristics were measured and plant biometrics were assessed by NDVI, NDRE, and SPAD measurements. The highest Se concentration of 315.19 mg kg−1 D.W. and the highest amount of Se taken up by plants (950.5 μg/pot) were observed for the low selenate rate with biochar. The corresponding values for selenite treatments were an order of magnitude lower. Although in general, minor to severe toxicity symptoms occurred with selenium application in no biochar treatments (except selenite low rate), the addition of biochar secured plant growth and increased S and P concentrations in plants, regulating Se uptake by plants at high selenite rate and allowing maximum plant uptake at the low selenate rate. To propose an appropriate Se fertilization rate, the fate of excess selenates in the soil environment should be examined and experimentation under soil conditions is necessary. [ABSTRACT FROM AUTHOR]

Numerous studies reported the positive effect of soil amendment with biochar on plant development. However, little is known about biochar and its interrelation with nitrogen (N) and phosphorous (P) additions and their impact on plant growth. We carried out greenhouse experiments to understand the interactive effects of nitrogen and phosphorus supply, as well as biochar amendment, on the symbiotic performance of soybean (Glycine max L.) with Bradyrhizobium japonicum, and plant growth and nutrient uptake. The biochar was produced from maize by heating at 600 °C for 30 min and used for pot experiments at an application rate of 2%. Plants were fertilized with two different concentrations of P (KH2PO4) and N (NH4NO3). Biochar application significantly increased the dry weight of soybean root and shoot biomass, by 34% and 42%, under low nitrogen and low phosphorus supply, respectively. Bradyrhizobium japonicum inoculation enhanced the dry weight of shoot biomass significantly, by 41% and 67%, in soil without biochar and with biochar addition, respectively. The nodule number was 19% higher in plants grown under low N combined with low or high P, than in high N combinations, while biochar application increased nodule number in roots. Moreover, biochar application increased N uptake of plants in all soil treatments with N or P supply, compared with B. japonicum-inoculated and uninoculated plants. A statistical difference in P uptake of plants between biochar and nutrient levels was observed with low N and high P supply in the soil. Our results show that the interactions between nitrogen, phosphorus, and biochar affect soybean growth by improving the symbiotic performance of B. japonicum and the growth and nutrition of soybean. We observed strong positive correlations between plant shoot biomass, root biomass, and N and P uptake. These data indicated that the combined use of biochar and low N, P application can be an effective approach in improving soybean growth with minimum nutrient input. [ABSTRACT FROM AUTHOR]

Biochar is widely used in agriculture to improve soil fertility and plant growth. However, a comprehensive assessment of how biochar amendment affects plant root growth is lacking. This study investigated the change in plant root biomass in response to biochar application, including impact factors such as the biochar feedstock and application rate, plant type, and soil pH. The Science Direct, Web Of Science, and Scopus databases were employed to search for literature published before 2021. The published papers with at least three replicates of biochar-amended treatments and a control at the same site were selected for meta-analysis. Our results showed that 165 (81.3%) of 203 datasets from 47 published studies indicated positive effects of biochar amendment on root growth with a mean relative increase of 32%. The feedstocks of biochar and its rate of application were the main factors that determined its effects on plant root growth. The increment of root biomass following biochar amendment was the greatest for trees (+101.6%), followed by grasses (+66.0%), vegetables (+26.9%), and cereals (+12.7%). The positive effects mainly depended on feedstock sources, with the highest positive effect (+46.2%) for gramineous, followed by woody plants (+25.8%) and green wastes (+21.1%). Linear regression analysis and SEM (Structural equation modeling) analysis showed that total nitrogen (TN) and available phosphorus (AK) are one of the most important factors affecting the increase of root biomass. These results suggest that biochar can be considered an effective amendment to improve root growth and soil fertility. Biochar feedstock sources, application rates, and plant types should be considered to assess the potential benefits of biochar for root growth and soil quality. [ABSTRACT FROM AUTHOR]

Smelter waste deposits pose environmental and health threats and require remediation actions. Phytostabilisation techniques, based on soil amendments, help to establish plant cover and limit the secondary emission of potentially toxic trace elements. However, methods to optimize their effectiveness are needed. The application of bacterial inoculants in combination with soil amendments in the remediation of soils and wastes contaminated with metals still has not been extensively tested. Therefore, the aim of this study was to determine the effectiveness of indigenous (Streptomyces sp., Pseudomonas sp.) and foreign (Streptomyces costaricanus) strains of bacteria in supporting grass growth on extremely contaminated waste slag. They were applied alone and in combination with compost mixed with phosphate fertilizer or iron oxide. The tested strains improved plant growth and increased plant availability of phosphorus. The interaction of the soil amendments and some bacterial strains also stimulated a decrease in the extractability of metals, likely through the phosphate-induced precipitation of lead. Our data show that the effectiveness of soil amendments in the phytostabilisation of heavily polluted smelter deposits can be enhanced by plant growth-promoting bacteria (PGPB). [ABSTRACT FROM AUTHOR]

A number of agriculture residues may be used either directly or after suitable treatment as amendments to improve soil quality. Such materials include biochar made of agriculture residues, digestate or elemental sulphur obtained from biogas desulphurisation. The joint use of these materials via pre-incubation may be more advantageous than only mixing prior the application to soil. In this study, digestates were mixed with amendments and incubated for 6 weeks before application to soil in a short-term pot experiment with lettuce (Lactuca sativa). The following treatments were tested: control digestate, digestate + biochar, digestate + elemental sulphur, digestate + biochar + elemental sulphur. The biochar-enriched digestate significantly increased soil microbial biomass, soil C:N, fresh above ground biomass, fresh and dry root biomass. Elemental sulphur-enriched digestate caused highest arylsulfatase and phosphatase, increased urease, microbial biomass in soil and fresh root biomass. Amendment of digestate + biochar + sulphur led to the significantly highest total soil carbon, microbial biomass, β-glucosidase, urease, and increased C:N ratio, arylsulfatase in soil and root biomass. It mitigated the adverse effect of either biochar or elemental sulphur on soil respiration. Properties of digestates were apparently affected by pre-incubation. This approach in digestate fertilizer production may contribute to sustainable farming. [ABSTRACT FROM AUTHOR]

Contamination by petroleum hydrocarbons (PHs) is a great threat to environment due to the higher persistence and bio-toxicity of PHs. Therefore, removal of PHs from contaminated environment and strategies to reduce their toxic effects on living organisms are crucial for environmental safety and human health. The toxic effects of PHs from the polluted soil can be reduced by the addition of microbes and biochar. In this study, a pot trial was carried out to evaluate the effects of sugarcane bagasse (SB) biochar and Bacillus sp. MN54 addition on phytoremediation of PHs and growth of maize (Zea mays L.) in soil artificially contaminated with diesel. Maize seeds were sown in uncontaminated or contaminated (with PHs) soil, treated with biochar and Bacillus sp. MN54. The results revealed that PHs showed significant phytotoxicity to maize plants and the application of strain MN54 and biochar greatly reduced the toxic effects of PHs on plants growth and physiology by increasing the nutrients uptake in PHs contaminated soil. Interestingly, the phytotoxicity of PHs on maize plants was further reduced in the co-supplementation of strain MN54 and biochar. Plants physiological (25–48%) and agronomic (38–47%) attributes were significantly higher as compared to only PHs contaminated soil in the co-supplementation of strain MN54 and biochar. Similarly, nitrogen (41%), phosphorus (43%) and potassium (37%) concentrations were also increased in the co-supplementation of strain MN54 and biochar. Furthermore, maize plants successfully phytoremediate a considerable amount of PHs from soil particularly in the presence of strain MN54 and biochar, and this PHs removal was further enhanced in the co-supplementation of strain MN54 and biochar (i.e., 46% and 77% of initial PHs were removed in unplanted and planted treatments, respectively). The present results indicate that co-supplementation of biochar and Bacillus sp. MN54 could be effective in enhancing the degradation of PHs and improving plant growth in the hydrocarbons contaminated soil. [ABSTRACT FROM AUTHOR]

Recently, biochar has been proposed for various agronomic applications including improved plant growth and soil fertility. In this study, the effects of dairy effluent-saturated (SBC) and unsaturated wood-derived biochar (UBC) on Bermudagrass (Cynodon spp.) growth, soil fertility and microbial communities were investigated in a greenhouse pot study. SBC and UBC were mixed with sandy loam soil at various loading rates (0, 1, 2, 4, and 8%) to grow Bermudagrass for 10 weeks. Soil physicochemical properties and plant growth measurements were taken, followed by 16S rRNA (V3-V4) amplicon sequencing of soil bacterial communities. Amendment of SBC to soil altered the soil physicochemical properties and increased the concentrations of N and P in the soil at 2 to 8% loading rates compared to UBC treated soil. The addition of SBC to soil also increased the overall plant biomass compared to UBC with more effects on aboveground biomass. Differential abundance analysis of taxa showed enrichment of Proteobacteria in UBC-amended soil, whereas Firmicutes and Nitrospirae were abundant in SBC-amended soil. Interestingly, enrichment of photosynthetic and N-fixing bacteria was observed in both SBC and UBC-amended soils after 10 weeks of treatments. However, oxidative phosphorylation and biotin metabolisms were found to be more abundant in SBC-amended soil compared to UBC-amended soil. Overall, our study suggested that amendment of SBC to soil resulted in enhanced soil nutrients, microbial capacity and Bermudagrass growth than that of UBC. Therefore, application of SBC to soil in field trials would be merited to identify sustainable and effective practices for enhancing plant growth, soil fertility and soil bacterial community. [ABSTRACT FROM AUTHOR]