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The application of biochar can effectively enhance soil organic matter (SOM) and improve soil structure. Biomass power plant ash (BPPA) is also rich in essential nutrients for plants, with similar carbon content. Considering production cost and agricultural waste recycling, it is beneficial to apply BPPA to improve soil fertility and quality. However, it remains unclear whether its ameliorative effects surpass those of biochar in alkaline soils. In the study, we set up seven pot experiments of faba beans in sandy alkaline soils from the ancient region of the Yellow River, including the controls (CK), different amounts of acid-modified BPPA (A1, A2, A3), and the same amounts of acid-modified biochar (B1, B2, B3), to compare their effects on soil physiochemical properties and bacterial community structure. The results indicate that the application of both biochar and BPPA can improve soil physiochemical properties. At the same dosage, the biochar application outperformed BPPA treatment in terms of soil physical properties such as bulk density (BD), maximum water-holding capacity (FC), and soil capillary porosity (SP2). Conversely, BPPA treatment displayed advantages in chemical properties such as readily oxidizable organic carbon (ROOC), total nitrogen (TN), alkaline nitrogen (AN), available phosphorus (AP), available potassium (AK), and electrical conductivity (EC). All the treatments enhanced the richness and diversity of bacterial communities, increasing the relative abundance of eutrophic groups such as Bacteroidota and Firmicutes while decreasing that of oligotrophic groups like Actinobacteriota. BPPA also increased the relative abundance of Proteobacteria, while the opposite was observed for biochar. Correlation analysis showed that the environmental factors such as soil pH, EC, TN, AK, SOM, and SP2 emerged as primary factors influencing the bacterial community structure of alkaline soils, significantly affecting their diversity and abundance. Among them, SP2 and SOM were the dominant physical and chemical factors, respectively. Overall, the application of both acid-modified BPPA and biochar can enhance the physiochemical properties of sandy alkaline soils, while the application of BPPA is superior for improving soil nutrient content and enhancing bacterial community structure. The study explores the potential mechanisms through which the application of acid-modified BPPA affects soil characteristics and microbial features, providing new insight into developing optimizing fertilization strategies for enhancing soil quality in the ancient region of the Yellow River. [ABSTRACT FROM AUTHOR]

Saline–alkali soils seriously restrict the soil functions and the growth and diversity of soil microorganisms. Biochar can alleviate the negative effects of saline–alkali stress. However, it remains unclear how biochar reduces saline–alkali stress by improving soil functions and regulating the abundance and diversity of the soil bacterial community in highly saline–alkali paddy fields. To address this, a paddy field experiment was conducted in a highly saline–alkali paddy field using two nitrogen application levels (0 and 225 kg ha−1) and four biochar application rates (0, 1.5%, 3.0%, and 4.5% biochar, w/w). The results show that, compared with C0, biochar application, especially when combined with N fertilizer, significantly decreased the soil pH, exchangeable sodium percentage (ESP), saturated paste extract (ECe), and sodium adsorption ratio (SAR) while significantly increasing cation exchange capacity (CEC). These indicated that biochar can effectively reduce saline–alkali stress. Biochar application significantly increased soil content of total nitrogen (TN), alkali-hydrolysable N (AN), available P (AP), available K (AK), soil organic matter (SOM), and soil C/N ratio, both with or without N fertilization. Furthermore, biochar application further increased the relative abundance of bacterial communities and modified the bacterial community structure in highly saline–alkali paddy soils. Under C3N2, C2N2, and C1N2, Chao1 increased by 10.90%, 10.42%, and 1.60% compared to C0N2. Proteobacteria, Bacteroidetes, and Chloroflexi were the top three phyla in bacterial abundance. Biochar significantly increased the abundance of Proteobacteria while reducing Bacteroidetes and Chloroflexi, regardless of N fertilization. Correlation analysis results showed that the improvements in soil chemical and saline–alkali properties, as well as nutrient bioavailability after biochar application, had a positive effect on bacterial communities in highly saline–alkali paddy soils. [ABSTRACT FROM AUTHOR]

Root-associated bacteria play a vital role in the soil ecosystem and plant productivity. Previous studies have reported the decline of bacterial community and rhizosphere soil quality in the cultivation of some medicinal plants (i.e., Pseudostellaria heterophylla). Phosphorus (P)-modified biochar has the potential to improve soil health and quality. However, its influence on the bacterial community and diversity in the rhizosphere of medicinal plants is not well understood. Therefore, this study aims to investigate the effects of P-modified biochar on the bacterial community and diversity in the rhizosphere of P. heterophylla. Soil samples were collected from the rhizosphere of 4-month P. heterophylla under control (no biochar), 3% unmodified and 3% P-modified biochar treatments, respectively. Compared with control and unmodified biochar treatment, P-modified biochar significantly increased the relative abundance of plant-beneficial bacteria (P < 0.05), particularly Firmicutes, Nitrospirae and Acidobacteria. The relative abundance of Bacillus, belonging to Firmicutes, was dramatically raised from 0.032% in control group to 1.723% in P-modified biochar-treated group (P < 0.05). These results indicate the potential enhancement of soil quality for the growth of medicinal plants. The application of biochar significantly increased bacterial richness and bacterial diversity (P < 0.05). P modification of biochar did not have significant effects on soil bacterial richness (P > 0.05), while it reduced Shannon and increased Simpson diversity index of soil bacterial communities significantly (P < 0.05). It indicates a decrease in bacterial diversity. This research provides a new perspective for understanding the role of P-modified biochar in the rhizosphere ecosystem. [ABSTRACT FROM AUTHOR]

Purpose: As a high-yield by-products of biogas engineering, biogas residue (BR) are limited in the application of soil fertility due to their ecological threat. Therefore, conversing BR into biochar is to be considered. However, whether BR biochar still had ecological risk to soils (especially the widely distributed soils such as Ultisol soil) remains to be probed. Materials and methods: Considering that soil microbial communities and carbon (C) pools play crucial roles in soil ecological environment, the soil bacterial communities, dissolved organic C (DOC) molecular structure, and bulk C mineralization in soils with BR (SBR) and BR biochar (produced at 300 °C, 600 °C, and 800 °C) addition (SBC) were explored in a microcosm incubation experiment using the Ultisol soil (clay loam soil). Soil without biochar addition was set as control (CK). The key technology of Fourier-transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS) was adopted in DOC molecular structure determination. Results and discussion: SBC300 and SBC600 significantly increased Shannon and Simpson indices by 4.3–7.7% and 2.3–2.6% than SBR. The abundance of Chloroflexi, Acidobacteria, Planctomycetes, and Firmicutes phyla were ordered with CK > SBC > SBR. ESI-FT-ICR-MS results showed that the DOC in SBC and SBR had more proteins, carbohydrates, and unsaturated hydrocarbons than in CK, and the highest increases emerged in SBC600. The soil C mineralization ability showed SBR > SBC > CK. The increase of SOC mineralization and the simplification of DOC molecular structure were significantly related to the increase of Proteobacteria and the decrease of Firmicutes. The structural equation modeling showed DOC concentration (SPC = − 0.300), bacterial community richness (SPC = 0.271), and diversity (SPC = − 0.939) were the important abiotic and biotic factors regulating C mineralization. Conclusions: In conclusion, the application of BR biochar had lower ecological risk than direct application of BR in the Ultisol soil. [ABSTRACT FROM AUTHOR]

This study investigated the effect of corn straw biochar on the decomposition, nutrient transformation, and bacterial community characteristics in the corn straw decomposition process. A 90-day microcosm incubation experiment was performed to assess the effects of corn straw biochar (500 °C, 1 h) on the corn straw decomposition process and the resulting product. Four biochar amendment rates (0%, 5, 10, and 15%, as mass fractions of biochar) and three different addition times (1st day, 30th day, and 60th day) were set in total. The results showed that corn straw biochar significantly increased the pH of the corn straw decomposition process by 0.71–0.73 and increased the electrical conductivity value by 0.64–1.07 μS/cm over that of the controls. In addition, biochar was shown to increase the temperature rise rate and temperature peak of the straw maturation system, and advance the process of straw maturation by 10 days. Thus, treatment with corn straw biochar could accelerate the corn straw decomposition process and change the conditions for microorganisms involved in the process. Furthermore, biochar additions significantly decreased the organic matter content by 9.67% under B3 and T1 treatment, and enhanced the N, P2O5, and K2O contents of the straw decomposition product by 0.36, 0.19, and 0.88% under B3 and T1 treatment. Biochar additions could increase the abundance of several effective bacteria closely related to the N, P2O5, and K2O contents of the straw maturation product. The growth of these bacteria was likely to be affected by the increase in pH with biochar addition, which enabled the improvement of the nutrient mineralization process. [ABSTRACT FROM AUTHOR]

Highlights • Biochar combined with enriched cultures addition in cow manure composting was studied. • Bacteria diversity and abundance remarkably enhanced in composting. • 12%WSB with bacteria culture treatment has maximum abundance of Firmicutes phyla. • Bacteroidales, Flavobacteriales and Bacilli were significantly higher abundance. Abstract The present work studied to evaluate the effectiveness under the interaction of bacterial consortium and biochar applied to give impetus to bacterial community activities among cow manure composting. High-throughput sequencing technique and six treatments were carried out: T2, T3 and T6 were single apply of bacteria culture (C), 12%wood biochar (12%WB) and 12%wheat straw biochar (12%WSB), respectively, while T4 and T5 were bacterial consortium combined with 12%WB and 12%WSB respectively, and T1 was used as control. The conclusion shows that the richness of bacterial community were most prosperity in T5 and T4 that in line with the statistical analysis angle of curves and cluster. The dominate phyla of Firmicutes, Proteobacteria and Bacteroidetes were accounted to 31.36%, 34.79% and 33.85%, the superior genera were Dysgonomonas (16.55%) , Empedobater (9.39%) , Atopostipes (13.42%) , Tissierella (8.25%) , Marinimicrobium (14.45%) and Pseudomonas (9%). Overall, bacterial consortium combined with biochar could stimulate microbe activity to accelerate degradation, enhance richness and alter specific selection of bacterial community. [ABSTRACT FROM AUTHOR]

To effectively improve soil productivity and optimize organic fertilizer management while reducing environmental pollution and resource wasting in farmland system, the present study was conducted in Wuqiao Experiment Station of China Agricultural University, Hebei Province. Taking crop straw treatment as control, four kinds of organic materials including pig manure (PM), biogas residue (BR), biochar (BC) and crop straw (ST) were applied to soil at the same nitrogen (N) level. The soil bacteria community characteristics were explored using Illumina Miseq high-throughput sequencing technologies. The results were as follows: (1) Compared with ST, PM, BR and BC had no significant effect on Chao 1 and Shannon index. The dominant bacterial groups include Proteobacteria, Acidobacteria, Actinobacteria, Bacteroidetes, and Chloroflexi in sandy loam soil after the application of different organic materials . The abundance of Proteobacteria in BC treatment was significantly lower than that of ST (control) treatment ( p < 0.05). On the contrary, compared to ST, the abundances of Acidobacteria increased by 65.0, 40.7, and 58.7% in the BC, BR, and PM treatments, respectively. (2) Compared to ST, the BC treatment significantly ( p < 0.05) increased in soil organic carbon (SOC) and pH in the arable layer (0-20 cm) in the farmland ( p < 0.05), and significantly increased the soil pH with a value of 0.26 level ( p < 0.05). (3) Pearson correlation analysis results showed that the PCoA1 scores and soil pH were closely correlated ( R = 0.3738, p < 0.05). In addition, pairwise regression between PCoA1 scores and SOC ( R = 0.5008, p < 0.05), PCoA2 scores and SOC ( R = 0.4053, p < 0.05) were both closely correlated. In general, our results indicated that organic materials amendment shaped the bacterial community in sandy loam soil through changing the soil pH and SOC. [ABSTRACT FROM AUTHOR]

Clay materials are commonly used in remediation techniques for heavy metal contaminated soil. In this study, a magnesium (Mg(OH) 2 /MgO)-montmorillonite was proposed to be utilized for heavy metals immobilization in contaminated soil, with the remediation efficiency evaluated through the toxicity characteristic leaching procedure (TCLP) and the community bureau of reference sequential extraction procedure (BCR). The addition of magnesium-montmorillonite resulted in lower TCLP extractability for the heavy metals (Cu, Pb, Zn and Cd) in soil as it promoted their conversion from acid soluble fraction to residual fraction. Meanwhile, MM raised the soil pH and water-soluble organic carbon (WSOC). It was demonstrated that the immobilization of heavy metal in the presence of magnesium-montmorillonite was primarily induced by electrostatic attraction, precipitation and chelation with water-soluble organic carbon. Interestingly, a decreased bacterial community diversity was observed in soil treated by magnesium-montmorillonite (MM). The presence of pure magnesium-montmorillonite promoted the relative abundance of Proteobacteria , Actinobacteria and Firmicutes but reduced that of Bacteroides and Acidobacteria. Our results suggest that integrating the biochar into montmorillonite-based amendments can alleviate the damage to soil microorganisms by weakening the negative correlation between the two factors (content clay and WSOC in soil) and soil bacteria. Image 1 • A new type of magnesium-montmorillonite (MM) served as soil amendments was prepared. • Soil pH and water-soluble organic carbon (WSOC) rised. • The addition of MM made less TCLP extractability for Cu, Pb, Zn and Cd in soil. • The presence of pure MM decreased bacterial community diversity in soil. • Integrating the biochar into MM can alleviate the damage to soil microorganisms. [ABSTRACT FROM AUTHOR]

• Biochar and cultures efficiently promote the immobilization of heavy metals. • Biochar and cultures improve process and hygiene quality of composting. • Bacteria richness notably enhanced under apply of biochar and culture. • Proteobacteria (56.22 %) and Bacteroidetes (35.40 %) were dominance phyla. • Biochar + bacteria consortium were showed significant correlation. This study evaluated the effect of integrated bacterial culture and biochar on heavy metal (HM) stabilization and microbial activity during pig manure composting. High-throughput sequencing was carried out on six treatments, namely T1-T6, where T2 was single application of bacteria culture (C), T3 and T5 were supplemented with 12 % wood (WB) and wheat-straw biochar (WSB), respectively, and T4 and T6 had a combination of bacterial consortium mixed with biochar (12 % WB and 12 % WSB, respectively). T1 was used as control for the comparison. The results show that the populations of bacterial phyla were significantly greater in T6 and T4. The predominate phylum were Proteobacteria (56.22 %), Bacteroidetes (35.40 %), and Firmicutes (8.38 %), and the dominant genera were Marinimicrobium (53.14 %), Moheibacter (35.22 %), and Erysipelothrix (5.02 %). Additionally, the correlation analysis revealed the significance of T6, as the interaction of biochar and bacterial culture influenced the HM adsorption efficiency and microbial dynamics during composting. Overall, the integrated bacterial culture and biochar application promoted the immobilization of HMs (Cu and Zn) owing to improved adsorption, and enhanced the abundance and selectivity of the bacterial community to promote degradation and improving the safety and quality of the final compost product. [ABSTRACT FROM AUTHOR]