芽孢杆菌作用贝壳，煅烧成为生物碳肥料

To mitigate soil degradation and decrease dependency on chemical inputs in agriculture, this study examined the joint effects of coconut shell biochar and Bacillus strain Ya-1 on soil fertility, rhizosphere bacterial communities, and the growth of chili (Capsicum annuum L.). A controlled pot experiment with four treatments was conducted: control (CK), biochar only (C), Bacillus strain Ya-1 only (B), and a combination of both (BC). The BC treatment significantly enhanced the soil carbon and available phosphorus contents by approximately 20% and the soil nitrogen content and pH by 18% and 0.3 units, respectively, compared to the control. It also increased microbial biomass carbon and nitrogen by 25% and 30%, respectively, indicating improved soil microbial diversity as shown by the highest Pielou evenness index and Shannon index values. The combined application of biochar and the Ya-1 strain resulted in a 15% increase in chili plant height and a 40% improvement in root dehydrogenase activity, suggesting enhanced nutrient uptake and metabolism. Metabolic profiling showed shifts in stress response and nutrient assimilation under different treatments. Collectively, these results indicate the potential of biochar and microbial inoculants to significantly promote soil and plant health, providing a sustainable strategy to improve agricultural productivity and reduce reliance on chemical inputs.

: The present study aimed to evaluate the use of agricultural waste as carriers in the bioformulation of two plant growth promoting bacteria (PGPR), Bacillus thuringiensis B9 and Bacillus pacificus B11 isolated from the tomato rhizosphere, and to determine the effect of different carriers and storage temperatures on bacterial survival. Three carriers, namely palm nut shell biochar, coffee pulp and soil, were inoculated with one of the strains, dehydrated and stored at ambient and refrigeration temperatures (4 ◦ C). Bacterial survival was evaluated for 150 days at 30-day intervals. The results showed that the number of bacterial cells present in the bioformulations decreased progressively with storage time at room temperature, but at refrigeration temperature, the bacterial population initially decreased before increasing until reaching its maximum population at 90 days and gradually decreasing afterward. Although the coffee pulp and biochar carriers stored at 4 ◦ C retained the viability of the bacterial strains as well as possible, the formulations stored at room temperature also remained viable.

Increasing salinity stress is a significant challenge in agriculture, affecting ~ 20% of irrigated areas worldwide. It can induce osmotic stress, oxidative stress, and nutrient imbalance in plants. Using rhizobacterial species and biochar can be an effective method to overcome this issue. Bacillus pumilus is a rhizobacteria that can enhance plant salt tolerance, facilitate nutrient solubilization in saline soils, and generate stress-alleviating metabolites. On the other hand, nitrilotriacetic acid mixed biochar (NAT-BC) can increase crop yields and mitigate salt stress by improving nutrients and water uptake. That’s why the present study was carried out to explore the combined effect of NAT-BC and Bacillus pumilus on sunflowers in both non-saline and salinity-stress on sunflowers. Four treatments, i.e., 0NAT-BC, Bacillus pumilus, 0.75NAT-BC, Bacillus pumilus + 0.75NAT-BC, were applied in four replications following a completely randomized design (CRD). Results showed that Bacillus pumilus + 0.75NAT-BC caused significant enhancement in sunflower plant height (103%), stem diameter (45%), head diameter (74%), stomatal conductance (60%), and protein content (11%) rate over control under salinity stress. A significant improvement in sunflower chlorophyll a (19%), chlorophyll b (35%), and total chlorophyll (54%) compared to the control confirm the efficacy of Bacillus pumilus + 0.75NAT-BC under salinity stress. It is concluded that applying treatment Bacillus pumilus + 0.75NAT-BC can alleviate salinity stress in sunflowers via improvement in total chlorophyll contents, which was the most representative attribute in the current study. Growers are recommended to apply Bacillus pumilus + 0.75NAT-BC to achieve better sunflower growth under salinity stress.

A two-season field study was conducted at ICAR-KVK, Hadonahalli, which is located in the Eastern Dry Zone of Karnataka, to evaluate the influence of phosphorus-solubilizing bacteria (PSB) and zinc-enriched coconut shell biochar on soil biological properties, nutrient bioavailability and soybean (Glycine max L.) yield in acidic soils. 13 treatments, including a control, package of practice and various combinations of PSB and zinc-enriched biochar were assessed in randomised complete block design at P=0.05 level of significance. The biochar was characterized for its physical properties, including bulk density (0.38 Mg m-3), water holding capacity (76.27%) and chemical properties including pH (9.52), electrical conductivity (1.12 dS m-1) and nutrient composition. Results indicated significant improvements in soil dehydrogenase activity, phosphatase activity and major nutrient bioavailability (N, P, K and Zn) in treatments receiving 100% NPK, PSB enriched FYM at 3.125 t ha-1 and different doses of zinc enriched Biochar at 5 t ha-1 compared to the control and package of practice. Soybean yield was maximized under treatments combining PSB-enriched FYM and zinc-enriched biochar, with the highest yield observed in T6 (23.61 q ha-1). The enhanced yield was attributed to improved soil health and nutrient dynamics by PSB and biochar. These findings underscore the potential of PSB and zinc-enriched biochar as sustainable amendments for enhancing soil fertility, crop productivity, and nutrient use efficiency in acidic soils.

Addressing the threat of heavy metal contamination in agriculture, this study evaluated the efficacy of crab shell biochar (CB) and compost (CO) in immobilizing copper (Cu), zinc (Zn), and lead (Pb). The objective was to determine the impact of solitary and combined applications of CB and CO on soil physicochemical properties, nutrient availability, HMs bioavailability, subsequent growth, and oxidative stress responses in spinach plants. The experiment involved two soil types (clay loam and sandy clay loam) with differing initial properties, which were simultaneously spiked with 300 mg kg−1 Cu, 500 mg kg−1 Zn, and 400 mg kg−1 Pb, aged for 30 days, and then treated with varying doses of CB and CO (e.g., 1% and 1.5% w/w). Key results demonstrated that the combined application of 1.5% CB + 1.5% CO was most effective, significantly (p < 0.05) increasing soil pH and reducing DTPA-extractable Cu (by 53–64%), Zn (42–50%), and Pb (57–59%) in both soil types. This treatment also led to a pronounced decrease in the bioaccumulation factor (BF) of HMs in spinach, coupled with improved plant growth parameters (height, fresh/dry weight, chlorophyll content) and reduced oxidative stress (as indicated by lower levels of MDA and antioxidant enzymes). We conclude that the synergistic interaction between CB and CO creates a multi-mechanistic immobilization system, offering a highly effective strategy for the remediation of heavy metal-contaminated soils and the safe cultivation of crops.

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<p style="line-height:150%;text-align:justify;"><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:150%;" lang="EN-US">Heavy metals like Pb, Cd, As, and Ni are becoming major environmental pollutants affecting crop productivity. The current study focused on the integration of biochar, compost, and Pb-tolerant </span><em><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:150%;" lang="EN-US">Bacillus</span></em><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:150%;" lang="EN-US"> sp. (N18) to mitigate the hazardous impacts of Pb and improve maize growth under normal and Pb-spiked contaminated soil. There are six treatments in both normal and contaminated soil, arranged in CRD (completely randomized design) under a factorial setting with three replications. The findings confirmed the synergistic role of the combined application of biochar, compost, and </span><em><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:150%;" lang="EN-US">Bacillus</span></em><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:150%;" lang="EN-US"> sp. (N18) in improving the growth of maize under both soils. The use of biochar+</span><em><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:150%;" lang="EN-US"> Bacillus</span></em><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:150%;" lang="EN-US"> sp. (N18) in contaminated soil significantly enhanced maize growth </span><em><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:150%;" lang="EN-US">viz.</span></em><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:150%;" lang="EN-US"> shoot, root length and their dry weight, antioxidant activity like SOD, POD, CAT, APX by 50.9, 82.6, 73.3, 46.7, 51.6, 42.5, 35 and 45.4%, respectively, over control. In contrast, significant reduction in the Pb uptake in maize root and straw under combined use of biochar and </span><em><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:150%;" lang="EN-US">Bacillus</span></em><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:150%;" lang="EN-US"> sp. (N18), with values of 61.9 and 65.5%, respectively, while after harvest, extractable Pb contents in soil were also reduced by 79.7% over control. The bioaccumulation and translocation factors were also decreased by the use of biochar + </span><em><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:150%;" lang="EN-US">Bacillus </span></em><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:150%;" lang="EN-US">sp</span><em><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:150%;" lang="EN-US">.</span></em><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:150%;" lang="EN-US"> (N18), which is 44.7 and 35.2% as compared with control. This dual behavior by synergizing organic amendments (compost and biochar) and </span><em><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:150%;" lang="EN-US">Bacillus</span></em><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:150%;" lang="EN-US"> sp. (N18) can efficiently bioremediate the Pb toxicity in soil and improve maize production, which can help developing sustainable bioremediation methods. </span></p>

Phosphorus (P) is an essential nutrient for rice growth, and the presence of phosphate-solubilizing bacteria (PSB) is an effective means to increase soil P content. However, the direct application of PSB may have minimal significance due to their low survival in soil. Biochar serves as a carrier that enhances microbial survival, and its porous structure and surface characteristics ensure the adsorption of Bacillus megaterium. Inoculating rice husk biochar-immobilized with Bacillus megaterium (BMB) resulted in dissolved inorganic and organic P levels of 39.55 and 31.97 mL L−1, respectively. Subsequently, rice pot experiments were conducted to investigate the response of soil microbial P mobilization and P uptake in rice to fertilizer inputs. The organic fertilizer (OF) combined with BMB treatment (MOF) showed the highest soil available phosphorus (AP) at 38 days, with a value of 7.83 mg kg−1, as well as increased the pqqC abundance while decreasing the abundance of phoD bacterial communities compared with the control. Furthermore, the bioavailable P reservoir (H2O–Pi and NaHCO3–Pi) in soil was greatly increased through the fertilizer input and microbial turnover, with the highest H2O–Pi (3.66 mg kg−1) in OF treatment and the highest NaHCO3–Pi (52.65 mg kg−1) in MOF treatment. Additionally, carbon utilization analysis was applied using the commercial Biolog system, revealing that the MOF treatment significantly increased the utilization of carbohydrates, polymers, and amino acid carbon sources. Moreover, compared to the control, MOF treatment significantly increased the shoot (0.469%) and root P (0.516%) content while promoting root development and thereby supporting rice growth. Our study demonstrates that the MOF treatment displayed higher P levels in both soil and rice plants, providing a theoretical basis for further understanding the role of biochar-based bacterial agents in rice P management.

Phosphorus (P) deficiency significantly limits pigeon pea growth in acidic soils. Applied P fertilizers tend to diffuse and bind to the active surface sites where they form insoluble complexes with aluminum and iron, rendering the P unavailable for plant uptake. The interactive effects of farmyard manure (FYM), P fertilizers, phosphate‐solubilizing bacterium, and maize biochar on P availability and plant growth in acidic soils remain largely unexplored. To enhance P availability in acidic soils, four P fertilizer formulations were developed and tested using pigeon pea as a test crop: (1) biochar‐enriched super phosphate and rock phosphate; (2) FYM‐enriched super phosphate and rock phosphate; (3) Biochar + FYM‐enriched super phosphate and rock phosphate; and (4) Bacillus megaterium‐fortified Biochar + FYM‐enriched super phosphate and rock phosphate. Field trials were conducted over 2 years to evaluate the effects of these treatments on P availability, uptake, bacterial community dynamics, and pigeon pea yield. The application of B. megaterium (~2 kg) fortified biochar and FYM‐enriched rock phosphate at 750 kg ha−1 significantly improved soil available P (10 mg kg−1), P uptake (21.7 kg ha−1) and Bacillus population (16% higher) compared to super phosphate alone. This formulation also enhanced acid phosphatase activity, microbial biomass phosphorus, biomass carbon, and microbial community composition, contributing to improved plant growth and seed yield (1558 kg ha−1). The combined application of B. megaterium (2 kg) and 50 kg P in biochar‐FYM‐enriched rock phosphate at 750 kg ha−1 demonstrated a sustainable approach for increased phosphorus availability and uptake in low pH soils. This eco‐friendly strategy improved pigeon pea production and reduced reliance on chemical fertilizers, presenting a viable solution for sustainable P management practices in acid soil.

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Storing biochar in soil is an effective method for improving the soil environment and reducing atmospheric greenhouse gases. Some strains of Bacillus species have been utilized as plant growth-promoting bacteria or biological control agents against plant diseases and pests. By colonizing biochar with beneficial bacteria, highly functional biochar that contributes to increased crop yields can be developed. In this study, we investigated the survival of type strains of eight Bacillus species (Bacillus amyloliquefaciens, B. licheniformis, B. nakamurai, B. pumilus, B. siamensis, B. subtilis, B. thuringiensis, and B. velezensis) in rice husk biochar, based on the sporulation state of vegetative cells or endospores. The bacterial density in the biochar significantly reduced when inoculated with a high concentration of vegetative cells, whereas it remained high when inoculated with a high concentration of spores. When water-washed biochar was inoculated with a high concentration of vegetative cells, survival significantly improved compared to that when unwashed biochar was inoculated. When a high concentration of vegetative cells was inoculated into the biochar water extract (biochar: water = 1:10), the bacterial densities of most species, except B. nakamurai and B. licheniformis, were significantly lower than those in alkali-sterilized water at pH 10.2 (same pH as biochar) and normal sterilized water (pH 6.7). These results suggest that the survival of Bacillus vegetative cells in biochar is inhibited by water-soluble inhibitors contained in the biochar rather than by alkaline conditions. When endospores were inoculated onto unwashed biochar, all strains maintained high viability for at least 12 weeks.

The use of amendments in combination with Bacillus subtilis has been understudied as a strategy for rehabilitating acid soils and improving cropping systems. This study aimed to evaluate the effects of amendments and B. subtilis on the development, yield, and nutritional quality of the hard yellow maize Marginal 28 T variety. A randomized complete block design with a factorial arrangement was employed, considering five amendments, including biochar, alongside the application of B. subtilis. The combination of biochar and B. subtilis significantly increased plant and ear height (p < 0.01), achieved a grain yield of 4.11 t ha−1, and reduced flowering time by seven days. Strong correlations were observed between male and female flowering (r = 0.99) and between stem diameter and leaf area (r = 0.95), indicating improved vegetative development. Soil pH and nutrient availability, such as phosphorus, were also enhanced. The combined use of amendments and B. subtilis optimizes yield and improves soil chemical properties. Thus, applying biochar and B. subtilis improves growth, yield, and soil quality, consolidating a promising strategy for sustainable agriculture in acid soils.

Agricultural plastic waste is a major environmental pollutant due to its non‐biodegradable nature. This study discusses the production of biodegradable pots (bio‐pots) using a biochar composed of banana pseudo‐stems and Bacillus sp. The isolated Bacillus sp. produced indole‐3‐acetic acid (IAA), solubilized potassium and phosphate, and secreted siderophores immobilized in banana pseudo‐stem biochar. X‐ray diffraction analysis revealed CaCO3 and KCl as the major elements, aside from carbon, released to the soil. Bio‐pots were made from banana pseudo‐stem biochar mixed with a Bacillus sp.–biochar composite at various formulations: 0%, 1%, 3%, 5%, and 10%. Mechanical testing indicated that the porous structure of the biochar contributed to low pot density and tensile strength. Moreover, the air‐filled spaces within the biochar enhanced water absorption, correlating with the amount of biochar used. Marigolds were cultivated outdoors in the bio‐pots to assess growth and yield. Our findings showed that those grown in biopot‐4 (10%) displayed improved growth and yield compared to the control group (grown in the ground). After 10 weeks, the control plants became infected with fungi and aphids, whereas those grown in biopot‐4 remained unaffected. In summary, bio‐pots incorporating 10% Bacillus sp.–biochar are eco‐friendly, reducing the need for chemical fertilizers, fungicides, and insecticides, while contributing to environmental sustainability. Moreover, the combination of biochar and Bacillus sp. is more effective than an unmixed form, since Bacillus sp. can inhabit and propagate in biochar pores if the conditions are otherwise unsuitable for growth.

The use of artificial addition of microbial consortia into soils is a key strategy to simultaneously alleviate the common contamination and continuous cropping obstacles. This study established the coconut shell charcoal (CSC) LY05 +LGY06 by immobilizing Bacillus sp. LY05 and B. cereus LGY06 on CSC particles, which effectively accelerated the removal of pendimethalin as a possible human carcinogen (91.68 %) and Cd2 + (80.02 %) from the culture-solution, and displayed the prominent re-usability and stability compared with their free coculture consortium. This consortium could detoxify pendimethalin via serial nitro-reduction, oxidation, cyclization, carboxylation and hydroxylation reactions. CSC LY05 +LGY06 could rapidly degrade pendimethalin in sterile (90.01 %) and non-sterile (99.03 %) soils. Moreover, it notably reduced pendimethalin and Cd2+ residuals in pod kernels, pod shells, and plants of peanut growing in continuous cropping soil by 99.19 % and 94.02 %, 99.16 % and 93.94 %, and 98.94 % and 91.85 %, respectively, contrasted to the control. Meanwhile, it significantly promoted the pod yield (>1.28-fold) and quality of continuous cropping peanut by improving the plant agronomic trait, photosynthetic capacity, intracellular water metabolism, nutrient transport capacity, and metabolic activity. This study provides a novel insight into the safe production of agri-products in continuous cropping soils con-contaminated by pesticides and heavy metals.

Soil organic carbon (SOC) loss in sloping farmland is a critical challenge for agricultural sustainability. This study investigated how citrus peel biochar (CPB), field snail shell powder (SSP), and their composite (CPB + SSP) differentially regulate SOC dynamics across slope positions (upper, middle, lower) in Guangxi’s citrus orchards. Key findings revealed: CPB significantly increased SOC content (up to 5.5 g·kg−1 at lower slopes) via high carbon input but suppressed mineralization amount in lower slope position (reduction of 17.9%) due to its high C/N ratio. SSP neutralized soil acidity (pH 3.95 to 7.5), stimulating microbial activity and raising mineralization rates by 58.95% (lower slope), yet minimally enhanced SOC (only +0.7 g·kg−1). CPB + SSP effectively balanced carbon stability and active release: dissolved organic carbon (DOC) and readily oxidizable organic carbon (ROC) increased by 14.4 mg·kg−1 and 0.22 g·kg−1 (middle slope), while SOC rose significantly (e.g., +2.2 g·kg−1 at lower slope). Slope position effects strongly influenced outcomes: the lower slope (highest initial SOC) responded most strongly to CPB for carbon stabilization, while middle slopes benefited from CPB + SSP to reconcile carbon loss with fertility. These results provide slope-specific strategies for SOC management by integrating amendment synergy and machine learning-driven insights in citrus orchards.

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Rice straws are a cheap source of fodder, but they are underutilized as feed due to their low voluntary intake and susceptibility to physical and microbial damage. The present study aimed to define the beneficial effect of calcined oyster shells and rock flour as preservative agents to maintain the physical appearance, palatable component, moisture, nutrient content, and nutritional value of rice straw preserved in an airtight wrapping method. Rice straws in intact and fresh form were sprayed with 1.2% molasses and 0.15% urea solution and sprinkled with 1% calcined oyster shell (cOS), 1% calcined rock flour (cRF), and a mixture of 0.5% cOS+0.5% cRF. The straws were preserved in airtight wrapping for 60 days. Fresh and preserved straws were assessed for organoleptic values, botanical fractions, and proximate and fiber fraction content. The nutritive values were evaluated through a feeding trial using young Pesisir bulls reared under a tethering herding system. There were four experimental diets: fresh rice straw (FRS), cOS preserved rice straw, cRF preserved rice straw, and cOS+cRF preserved rice straw. Parameters measured included DM intake, weight gain, blood hematology, protein, and mineral profiles. Results found that preserved rice straws had higher moisture and crude protein content than fresh straws. Preserved rice straws supplemented with a mixture of calcined shells and rock flour had significantly better texture and microbial status than that of either calcined shell or rock flour. Feeding preserved rice straw supplemented with a mixture of calcined shells and rock flour improved body weight gain that was not significantly different from the fresh straw. In conclusion, using preservatives as a mixture of calcined shells and rock flours produces the best-preserved rice straw for feeding cattle.

Excessive N fertilizer application has aggravated soil acidification and loss of N. Although oyster shell powder (OSP) can improve acidic soil, few studies have investigated its ability to retain soil N. Here, the physicochemical properties of latosol after adding OSP and calcined OSP (COSP) and the dynamic leaching patterns of ammonium N (NH4+-N), nitrate N (NO3−-N), and Ca in seepage, were examined through indoor culture and intermittent soil column simulation experiments. Various types of N fertilizer were optimized through the application of 200 mg/kg of N, urea (N 200 mg/kg) was the control treatment (CK), and OSP and COSPs prepared at four calcination temperatures—500, 600, 700, and 800 °C—were added to the latosol for cultivation and leaching experiments. Under various N application conditions, the total leached N from the soil followed ammonium nitrate > ammonium chloride > urea. The OSP and COSPs had a urea adsorption rate of 81.09–91.29%, and the maximum reduction in cumulative soil inorganic N leached was 18.17%. The ability of COSPs to inhibit and control N leaching improved with increasing calcination temperature. Applying OSP and COSPs increased soil pH, soil organic matter, total N, NO3−-N, exchangeable Ca content, and cation exchange capacity. Although all soil enzyme activities related to N transformation decreased, the soil NH4+-N content remained unchanged. The strong adsorption capacities for NH4+-N by OSP and COSPs reduced the inorganic N leaching, mitigating the risk of groundwater contamination.

Introduction The objective of this study is to examine the impact of various oyster shell soil conditioners, which are primarily composed of oyster shells, on the growth of tomatoes in acidic soil. Moreover, the aim of this investigation is to analyze the variety and structure of soil bacterial populations in close proximity to tomato roots while also contributing to the understanding of the physical, chemical, and biological mechanisms of oyster shell soil conditioners. Methods Tomato plants were grown in acidic red soil in three groups: a control group and a treatment group that used two types of oyster shell soil conditioners, OS (oyster shell powder) and OSF (oyster shell powder with organic microbial fertilizer). A range of soil physicochemical properties were measured to study differences in inter-soil physicochemical parameters and the growth of tomato plantings. In addition, this study utilized the CTAB (Cetyltrimethylammonium Bromide) technique to extract DNA from the soil in order to investigate the effects of oyster shell soil conditioner on the composition and diversity of bacterial populations. Utilizing high-throughput sequencing technologies and diversity index analysis, the composition and diversity of bacterial populations in the soil adjacent to plant roots were then evaluated. Ultimately, correlation analysis was used in this study to explore the relationship between environmental factors and the relative abundance of soil bacteria in the inter-root zone of tomato plants. Results The findings indicated that the oyster shell soil conditioners were capable of modifying the physicochemical characteristics of the soil. This was evidenced by significant increases in soil total nitrogen (16.2 and 59.9%), soil total carbon (25.8 and 27.7%), pH (56.9 and 55.8%), and electrical conductivity (377.5 and 311.7%) in the OS and OSF groups, respectively, compared to the control group (p < 0.05). Additionally, data pertaining to tomato seed germination and seedling growth biomass demonstrated that both oyster shell soil conditioners facilitated the germination of tomato seeds and the growth of seedlings in an acidic red clay soil (p < 0.05). On the other hand, the application of two oyster shell soil conditioners resulted in a modest reduction in the diversity of inter-root soil bacteria in tomato plants. Specifically, the group treated with OSF exhibited the most substantial fall in the diversity index, which was 13.6% lower compared to the control group. The investigation carried out on the soil between tomato plant roots yielded findings about the identification of the ten most abundant phyla. These phyla together represented 91.00-97.64% of the overall abundance. In the inter-root soil of tomatoes, a study identified four major phyla, namely Proteobacteria, Bacteroidetes, Acidobacteria, and Actinobacteria, which collectively accounted for up to 85% of the total abundance. At the general level, the relative abundance of Massilia increased by 2.18 and 7.93%, Brevundimonas by 5.43 and 3.01%, and Lysobacter by 3.12 and 7.49% in the OS and OSF groups, respectively, compared to the control group. However, the pathogenic bacteria unidentified_Burkholderiaceae decreased by 5.76 and 5.05%, respectively. The correlation analysis yielded conclusive evidence indicating that, which involved the use of CCA (Canonical Correlation Analysis) graphs and Spearman correlation coefficients, pH exhibited a positive correlation (p < 0.05) with Shewanella and a negative correlation (p < 0.05) with Bradyrhizobium. The relative abundance of Lysobacter and Massilia exhibited a positive correlation with the levels of total soil nitrogen. Discussion The utilization of oyster shell soil conditioner on acidic red soil resulted in several positive effects. Firstly, it raised the pH level of the inter-root soil of tomato plants, which is typically acidic. This pH adjustment facilitated the germination of tomato seeds and promoted the growth of seedlings. In addition, the application of oyster shell soil conditioner resulted in changes in the structure of the bacterial community in the inter-root soil, leading to an increase in the relative abundance of Proteobacteria and Bacteroidetes and a decrease in the relative abundance of Acidobacteria. Furthermore, this treatment fostered the proliferation of genera of beneficial bacteria like Massilia, Brevundimonas, and Lysobacter, ultimately enhancing the fertility of the red soil.

The golden apple snail is a significant pest that damages crops and can lead to crop failure because it has a habit of consuming various soft plants, including young rice plants. Golden snail shells have a high calcium carbonate content of around 60.56%. Large calcium content can be used as a source for the production of calcium nitrate fertilizer. The stages in making calcinit fertilizer are washing the shell of gold snails and drying for 1-2 days. After that, size reduction is carried out to 50 mesh. After that, the calcination process was carried out with a variable temperature of 700,750,800,850,900 ℃ for 4 hours. The calcined shell is dissolved with HNO3 with a variable of 1-5 N for 1 hour. After that the solution is filtered from impurities and neutralized to pH 7. After that the solution is crystallized into white crystals. The largest Ca and N content was obtained at a calcining temperature of 900 and HNO3 5 N concentrations, namely Ca of 21.94% and N of 16.52%. The results showed that the higher the calcining temperature and the higher the HNO3 content, the higher the Ca content and N content

Continuous cropping decreases soil nutrients and destroys microbial community structure, so the development of eco-friendly and effective biofertilizers is necessary under present conditions. In this study, the preserving microalgal strain Tribonema sp. (H) was firstly selected to be combined with agroforestry waste (shell powder, straw fermentation liquid) and the agroforestry microorganism Bacillus sp. to form microalgae-based fertilizers for the continuous cropping soil of potted tomato. Compared to the control (CK), microalgae-based fertilizers (concentration: 4.45 × 106 cells/ml, dosage: 20 ml/day) improved soil nutrients and salinization indicators. Specifically, the combination of Tribonema sp. and shell powder (HB) reduced electrical conductivity (EC) by 33.7% and significantly increased the Ca2+ content by 59.4%; Tribonema sp. and Bacillus sp. (HY) improved the effects of available phosphorous (AP), DOC, DON, NH4 +-N, NO3 −-N, and Mg2+ in the soil by 27.4%, 231.3%, 403.4%, 125.2%, 215.6%, and 73.4%, respectively. Microalgae-based fertilizers alter the abundance of soil bacteria and fungi, causing beneficial bacteria such as Thermonaerobaculia, Subgroup_10, Sordariomycetes, and Microascaceae to increase, while pathogenic bacteria like Pseudomonas, Togniniaceae, and Phaeoacremonium decreased. Combining microalgae with agroforestry wastes as a biofertilizer is promising to improve the microbial community structure of the soil with continuous cropping, which will aid in the increase of tomato production and promote green agricultural development.

To investigate the degradation efficiency of conditioners and commercial microbial agents on estrogens (E1, 17α-E2, 17β-E2, E3, EE2, and DES) in the composting process of dairy manure, seven different treatments (RHB-BF, OSP-BF, SD-BF, MR-BF, MR-FS, MR-EM, and MR-CK) under forced ventilation conditions were composted and monitored regularly for 30 days. The results indicated that the removal rates of estrogens in seven treatments ranged from 95.35% to 99.63%, meanwhile the degradation effect of the composting process on 17β-Estradiol equivalent (EEQ) was evaluated, and the removal rate of ΣEEQ ranged from 96.42% to 99.72%. With the combined addition of rice husk biochar (RHB) or oyster shell powder (OSP) and bio-bacterial fertilizer starter cultures (BF), namely RHB-BF and OSP-BF obviously promoted the rapid degradation of estrogens. 17β-E2 was completely degraded on the fifth day of composting in OSP-BF. Microbial agents have some promotional effect and enhances the microbial degradation of synthetic estrogen (EE2, DES). According to the results of RDA, pH and EC were the main environmental factors affecting on the composition and succession of estrogen-related degrading bacteria in composting system. As predominant estrogens-degrading genera, Acinetobacter, Bacillus, and Pseudomonas effected obviously on the change of estrogens contents. The research results provide a practical reference for effective composting of dairy manure to enhancing estrogens removal and decreasing ecological risk.

Barnacles as periphyte animals often found clinging on the ship’s hull, being unutilized waste that presents in such abundance. Calcium carbonate in barnacle shells would increase the chance of degrading microbial community survival in the soil, indirectly increasing soil fertility. The processing of barnacle shells to be used as a calcium carbonate supplement involves harvesting, drying, powdering, sterilizing, and mixing it to the soil. We want to observe comparison of the performance of control group (K), processed barnacle shells (T), industrial 16-16-16 NPK (Nitrogen, Phosphate, Potassium) fertilizer (P), and the combination of processed barnacle shell with 16-16-16 NPK fertilizer (TP) supplementation to the soil as planting media by the daily temperature, pH, and moisture fluctuation, besides the measurement of the growth of mung bean plant, Vigna radiata L. (VIMA 5 variant) regarding their application to the soil. The growth of V. radiata L. is measured by epicotyl length, number of leaves, and total wet mass increase of each plant individual. Vigna radiata L. in the control group shows the best growth measured by parameters listed above. However, ANOVA analysis shows statistical significance on the correlation of types of soil treatment (K, T, P, or TP supplementation) to daily moisture fluctuation.

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The plant-microbe holobiont has garnered considerable attention in recent years, highlighting its importance as an ecological unit. Similarly, manipulation of the microbial entities involved in the rhizospheric microbiome for sustainable agriculture has also been in the limelight, generating several commercial bioformulations to enhance crop yield and pest resistance. These bioformulations were termed biofertilizers, with the consistent existence and evolution of different types. However, an emerging area of interest has recently focused on the application of these microorganisms for waste valorization and the production of “bio-organic” fertilizers as a result. In this study, we performed a bibliometric analysis and systematic review of the literature retrieved from Scopus and Web of Science to determine the type of microbial inoculants used for the bioconversion of waste into “bio-organic” fertilizers. The Bacillus, Acidothiobacillus species, cyanobacterial biomass species, Aspergillus sp. and Trichoderma sp. were identified to be consistently used for the recovery of nutrients and bioconversion of wastes used for the promotion of plant growth. Cyanobacterial strains were used predominantly for wastewater treatment, while Bacillus, Acidothiobacillus, and Aspergillus were used on a wide variety of wastes such as sawdust, agricultural waste, poultry bone meal, crustacean shell waste, food waste, and wastewater treatment plant (WWTP) sewage sludge ash. Several bioconversion strategies were observed such as submerged fermentation, solid-state fermentation, aerobic composting, granulation with microbiological activation, and biodegradation. Diverse groups of microorganisms (bacteria and fungi) with different enzymatic functionalities such as chitinolysis, lignocellulolytic, and proteolysis, in addition to their plant growth promoting properties being explored as a consortium for application as an inoculum waste bioconversion to fertilizers. Combining the efficiency of such functional and compatible microbial species for efficient bioconversion as well as higher plant growth and crop yield is an enticing opportunity for “bio-organic” fertilizer research.

Planetary habitation requires technology to maintain natural microbial processes, which make nutrients from biowaste available for plant cultivation. This study describes a 646 day experiment, in which trickling filters were monitored for their ability to mineralize nitrogen when loaded with artificial urine solutions of different concentrations (40, 60, 80 and 100% v/v). Former studies have indicated that increasing urine concentrations slow nitrogen conversion rates and induce growing instability. In the current experiment, nitrogen conversion rates, measured as nitrate production/day, did not differ between concentration levels and increasing instability was not observed. Instead, the buffering capacity of the mussel shells added as buffer system (∼75% calcium carbonate) increased with increasing concentrations of synthetic urine possibly due to the higher phosphate content. The intensified precipitation of calcium phosphates seems to promote carbonate dissolution leading to improved buffering. For space applications, the precipitation of calcium phosphates is not desirable as for the phosphate to be available to the plants the precipitate must be treated with hazardous substances. With regard to terrestrial agriculture the process-integrated phosphate precipitation is a possibility to separate the macronutrients nitrogen and phosphate without addition of other chemicals. Thus, the described process offers a simple and cost-effective approach to fertilizer production from biogenic residues like slurry.

Seeking effective measures for the improvement of high-selenium and high-cadmium soils holds significant theoretical and practical importance for sustainable agricultural development. This paper focuses on conducting a site-specific soil survey in the characteristic agricultural product production area of Hefeng County, Enshi Prefecture, Hubei Province. Through field experiments, we compared 14 soil improvement methods across three techniques: chemical passivation remediation, agronomic regulation, and microbial remediation. The study investigated their impacts on rice Cd content, rice Se content, yield, and quality and conducted a comprehensive evaluation of the remediation effects of the different treatments. The experimental results indicate that (1) increasing the content of soil conditioners can enhance rice yields, with Treatment 14 showing the most significant increase, yielding an additional 257.3 kg per mu, representing a 55.62% increase. Treatment 12 also demonstrated a notable yield increase of 95.1 kg per mu, or a 20.55% increase. Lime, sepiolite, and shell powder can effectively reduce rice’s absorption of Cd. Treatment 9 resulted in the lowest Cd content in the rice, at 0.03 mg/kg, with a Cd reduction rate of 92%. The optimal application rates for this Cd reduction were 200 kg/mu of lime, 125 mL/mu of foliar inhibitor, and 50 kg/mu of carbon-silicon fertilizer. Treatment 12 achieved a rice Cd content of 0.11 mg/kg, with a 70% reduction in Cd, bringing the rice Cd content down to below 0.2 mg/kg, which meets the requirements of the National Food Safety Standard: Maximum Levels of Contaminants in Foods. In the comprehensive scoring of all treatments, considering four evaluation indicators—rice Cd content, rice yield, rice quality, and cost—Treatment 12 (300 kg/mu of soil conditioner + 50 kg/mu of carbon-silicon fertilizer) was found to be the optimal treatment through comparative scoring. It demonstrates good potential for ensuring safe rice production and can serve as a reference standard for repairing Cd-contaminated rice paddies in the local area, with promotional value.

Biochar has pores suitable for microbial habitat, and it contains carbon which can be used as an energy source by microbes. The research aims to determine the potential of some biochar as a carrier of biological fertilizer for swamplands. The treatment given was the type of biochar (rice husk, coconut shell, and palm empty fruit bunches) and the microbial type ie decomposer, Phosphate Solubilizing Bacteria (PSB), N Fixing Bacteria, and a consortium microbial. The design used was a Factorial Complete Randomized Design, 3 replications. Biochar analysis included organic C, total N, pH, CEC, SiO2, ash content and water content. Calculation of microbial populations was done at 2, 6 and 10 weeks after inoculation. Biochar rice husks, oil palm empty fruit bunches and coconut shells were very effective as decomposer carrier material. The highest of population of N-fixing bacteria and PSB at 6 weeks after inoculation was in the biochar rice husk reached 0.33 x 106 cfu/g for N-fixing bacteria and 54.8 x 106 cfu/g for P solvent bacterial. Rice husk biochar can be used as a carrier material both for a single biofertilizer, as well as a consortium biofertilizer that consists of decomposer fungi, P solubilizing bacteria and N-fixing bacteria.

Plant growth-promoting bacteria (PGPB) are an effective tool for improving nutrients in agricultural systems; however, their efficacy depends on successful colonization in soils. To address this challenge, biochar has been identified as an effective material for enhancing soil ecosystem services and can serve as a protective for PGPB. However, the impact of biochar and PGPB on soil health indicators and plant growth remains poorly understood. This study aimed to evaluate the effects of biochar and PGPB on soil chemical and biological properties in cowpea. We used biochar from bean husk (BHB) and grape fermentation residue (GFB) and Bradyrhizobium elkanii USDA 76 (BRA), Burkholderia cepacia ATCC 25416 (PRB), or Rhizobium altiplani BR10423 (RHI). BHB and PRB stimulated cowpea growth, while GFB and PRB promoted soil phosphatase activity. Overall, different combinations of biochar and PGPR increased soil pH, phosphorus, potassium, organic carbon content, and urease activity, but did not affect microbial biomass carbon and β-glucosidase activities. The biochars inoculated with the BRA showed the highest productivity. For example, plants subjected to the BRA + GFB treatment exhibited a 3.85-fold increase in productivity compared to the additional treatment that involved the use of commercial peat. The study demonstrated a positive effect of biochar and PGPB on soil enzymatic activity, nutrient content, and cowpea growth suggesting a sustainable alternative to chemical fertilizers, especially in poor soils. These findings highlight the potential of biochar as an environmentally sustainable carrier of PGPB while addressing the issue of agricultural waste reuse.

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Drought stress can significantly affect plant growth and development. Biochar (BC) and plant growth-promoting rhizobacteria (PGPR) have been found to increase plant fertility and development under drought conditions. The single effects of BC and PGPR in different plant species have been widely reported under abiotic stress. However, there have been relatively few studies on the positive role of PGPR, BC, and their combination in barley (Hordeum vulgare L.). Therefore, the current study investigated the effects of BC from Parthenium hysterophorus, drought tolerant PGPR (Serratia odorifera), and the combination of BC + PGPR on the growth, physiology, and biochemical traits of barley plants under drought stress for two weeks. A total of 15 pots were used under five treatments. Each pot of 4 kg soil comprised the control (T0, 90% water), drought stress alone (T1, 30% water), 35 mL PGPR/kg soil (T2, 30% water), 2.5%/kg soil BC (T3, 30% water), and a combination of BC and PGPR (T4, 30% water). Combined PGPR and BC strongly mitigated the negative effects of drought by improving the shoot length (37.03%), fresh biomass (52%), dry biomass (62.5%), and seed germination (40%) compared to the control. The PGPR + BC amendment treatment enhanced physiological traits, such as chlorophyll a (27.9%), chlorophyll b (35.3%), and total chlorophyll (31.1%), compared to the control. Similarly, the synergistic role of PGPR and BC significantly (p< 0.05) enhanced the antioxidant enzyme activity including peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD) to alleviate the toxicity of ROS. The physicochemical properties (N, K, P, and EL) of the soils were also enhanced by (85%, 33%, 52%, and 58%) respectively, under the BC + PGPR treatment compared to the control and drought stress alone. The findings of this study have suggested that the addition of BC, PGPR, and a combination of both will improve the soil fertility, productivity, and antioxidant defense systems of barley under drought stress. Therefore, BC from the invasive plant P. hysterophorus and PGPR can be applied to water-deficient areas to improve barley crop production.

Spent mushroom substrate (SMS) is the by-products of mushroom production, which is mainly composed of disintegrated lignocellulosic biomass, mushroom mycelia and some minerals. The huge output and the lack of effective utilization methods make SMS becoming a serious environmental problem. In order to improve the application of SMS and SMS derived biochar (SBC), composted SMS (CSMS), SBC, combined plant growth-promoting rhizobacteria (PGPR, Bacillus subtilis BUABN-01 and Arthrobacter pascens BUAYN-122) and SBC immobilized PGPR (BCP) were applied in the lettuce seedling. Seven substrate treatments were used, including (1) CK, commercial control; (2) T1, CSMS based blank control; (3) T2, T1 with combined PGPR (9:1, v/v); (4) T3, T1 with SBC (19:1, v/v); (5) T4, T1 with SBC (9:1, v/v); (6) T5, T1 with BCP (19:1, v/v); (7) T6, T1 with BCP (9:1, v/v). The physicochemical properties of substrate, agronomic and physicochemical properties of lettuce and rhizospheric bacterial and fungal communities were investigated. The addition of SBC and BCP significantly (p < 0.05) improved the total nitrogen and available potassium content. The 5% (v/v) BCP addiction treatment (T5) represented the highest fresh weight of aboveground and underground, leave number, chlorophyll content and leaf anthocyanin content, and the lowest root malondialdehyde content. Moreover, high throughput sequencing revealed that the biochar immobilization enhanced the adaptability of PGPR. The addition of PGPR, SBC and BCP significantly enriched the unique bacterial biomarkers. The co-occurrence network analysis revealed that 5% BCP greatly increased the network complexity of rhizospheric microorganisms and improved the correlations of the two PGPR with other microorganisms. Furthermore, microbial functional prediction indicated that BCP enhanced the nutrient transport of rhizospheric microorganisms. This study showed the BCP can increase the agronomic properties of lettuce and improve the rhizospheric microbial community.

Recommended Citation EGAMBERDIEVA, DILFUZA; ALAYLAR, BURAK; ALIMOV, JAKHONGIR; JABBAROV, ZAFARJON; and KIMURA, SONOKO BELLINGRATH (2023) "Combined effects of biochar and plant growth promoting bacteria Pseudomonas putida TSAU1 on plant growth, nutrient uptake of wheat, and soil enzyme activities," Turkish Journal of Agriculture and Forestry: Vol. 47: No. 3, Article 8. https://doi.org/10.55730/ 1300-011X.3092 Available at: https://journals.tubitak.gov.tr/agriculture/vol47/iss3/8

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Arsenic (As) contamination is a major environmental pollutant that adversely affects plant physiological processes and can hinder nutrients and water availability. Such conditions ultimately resulted in stunted growth, low yield, and poor plant health. Using rhizobacteria and composted biochar (ECB) can effectively overcome this problem. Rhizobacteria have the potential to enhance plant growth by promoting nutrient uptake, producing growth hormones, and suppressing diseases. Composted biochar can enhance plant growth by improving aeration, water retention, and nutrient cycling. Its porous structure supports beneficial microorganisms, increasing nutrient uptake and resilience to stressors, ultimately boosting yields while sequestering carbon. Therefore, the current study was conducted to investigate the combined effect of previously isolated Bacillus faecalis (B. faecalis) and ECB as amendments on maize cultivated under different As levels (0, 300, 600 mg As/kg soil). Four treatments (control, 0.5% composted biochar (0.5ECB), B. faecalis, and 0.5ECB + B. faecalis) were applied in four replications following a completely randomized design. Results showed that the 0.5ECB + B. faecalis treatment led to a significant rise in maize plant height (~ 99%), shoot length (~ 55%), root length (~ 82%), shoot fresh (~ 87%), and shoot dry weight (~ 96%), root fresh (~ 97%), and dry weight (~ 91%) over the control under 600As stress. There was a notable increase in maize chlorophyll a (~ 99%), chlorophyll b (~ 81%), total chlorophyll (~ 94%), and shoot N, P, and K concentration compared to control under As stress, also showing the potential of 0.5ECB + B. faecalis treatment. Consequently, the findings suggest that applying 0.5ECB + B. faecalis is a strategy for alleviating As stress in maize plants.

Microbial induced carbonate precipitation (MICP) is a promising technique for remediating Cd-contaminated soils. However, the high cost and potential disruption to soil micro-ecology due to the excessive urea addition remain significant challenges, limiting the broader application of MICP technology in agricultural soils. This study aims to improve the efficiency of Cd immobilization by MICP under low urea levels by investigating the stimulatory effect of porous materials on urease secretion by ureolytic bacteria. Results demonstrate that these materials, including biochar, activated carbon, zeolite, and oyster shell, can stimulate the growth of ureolytic bacteria strain kp-22, but not diatomite. Urease activity was greatly improved within 12 hours, and the Cd removal rate reached over 82.12% within 0.5 hours. Notably, biochar supported urealytic bacterium strain kp-22 (BCM) can steadily remove Cd in solution, with the Cd removal rate remaining close to 99% even after multiple additions of Cd. XRD analysis shows that Cd was removed by BCM due to the formation of CdCO3. Soil experiment reveals that BCM significantly decreased the bioavailable Cd content in both flooded and unflooded paddy soils, even when the urea addition was at a dosage suitable for agricultural production. 16S rRNA gene sequencing shows that the disturbance caused by BCM to the soil bacterial community was lower than that caused by strain kp-22 alone. These findings offer new insights into enhancing the efficiency of MICP for Cd remediation, increasing the potential for broader application of MICP technology in sustainable agriculture.

The contradiction between population growth and soil degradation has been increasingly prominent, such that novel fertilizers (e.g., biochar and microbial fertilizers) should be urgently developed. Biochar is a promising fertilizer carrier for microbial fertilizers due to its porous structure. However, the preparation and mechanisms of the effects of biochar-based microbial fertilizers have been rarely investigated. In this study, biochar, Bacillus, and exogenous N-P-K fertilizers served as the raw materials to prepare biochar-based microbial fertilizers (BCMFs) by optimizing the preparation methods and the process parameters. Moreover, the release patterns of N-P-K were analyzed. A pot experiment was performed on pakchoi to examine the effect of the BCMFs and explore its synergistic effect on soil fertility. The results of this study indicated that adsorption by biochar maintained bacterial activity, whereas the granulation process reduced bacterial activity. The adsorption-granulation process increased the content of total nitrogen and organic matter in the soil while enhancing the slow-release effect of the BCMFs. The Elovich model was capable of describing the nitrogen release of the BCMFs, including the diffusion and chemical processes. As indicated by the result of the column leaching experiment, the BCMFs stopped nutrient leaching more significantly than the conventional fertilizers (CF), especially in stopping N and P leaching. The use of the BCMFs improved the available soil nutrients and soil quality while enhancing the abundance of bacteria correlated with carbon and nitrogen metabolism in the soil. Moreover, a 20 % reduction in the use of the BCMFs did not significantly affect the soil available N and P and the growth status of pakchoi. The result of redundancy analysis indicated that the cation exchange capacity (CEC), NH4+-N, NO3--N, β-glucosidase (BG), urease (URE), and alkaline phosphatase (AlkP) were the six critical environmental factors for the microbial community structure and could explain 94.8 % of the variance. The BCMFs up-regulated the levels of the above six factors, especially CEC and BG, thus improving the soil quality and enhancing the soil fertility.

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