Search Results (133)

Plant growth-promoting rhizobacteria (PGPR) are microorganisms that enhance plant growth through various mechanisms. In the context of global agriculture, which faces fertilizer dependency and environmental pollution, developing eco-friendly microbial fertilizers has become crucial for enhancing agricultural sustainability. To identify highly effective PGPR, we isolated 102 bacterial strains from maize rhizosphere soil using the dilution plating method. The strains were screened for growth-promoting abilities using functional media, resulting in the selection of strain YMK25 for its exceptional capabilities in nitrogen fixation, solubilization of inorganic and organic phosphorus, indole-3-acetic acid (IAA) production, and siderophore production. Strain YMK25 produced IAA at a concentration of 80.49 ± 0.68 μg/mL and exhibited a relative siderophore expression level of 43.68%. Morphological analysis, 16S rDNA gene sequence analysis, and whole-genome sequencing confirmed that strain YMK25 is Klebsiella pneumoniae. Whole-genome analysis revealed a total genome length of 5,115,280 bp, a GC content of 57.61%, and it contained 4746 coding genes. Gene annotation results indicated genes involved in siderophore synthesis, phosphatase activity, and other plant growth-promoting functions, which align with the verified characteristics of strain YMK25. Furthermore, this strain exhibited significant metabolic capabilities. The pot experiment demonstrated that strain YMK25 promotes maize plant growth and assists in nutrient fixation in these plants. In conclusion, strain YMK25 is a high-quality PGPR with substantial potential for application in agricultural production, presenting promise for widespread use in sustainable agriculture. Full article

Organic amendments, such as straw, biochar, and animal manure, have been demonstrated to enhance soil phosphorus (P) availability effectively; however, the long-term impacts and underlying mechanisms require further study. Based on a long-term field experiment, this research systematically analyzed the effects of biochar (BIO), biochar-based fertilizer (BF), straw-returning (CS), and pig manure compost (PMC) on soil phosphorus transformation and crop phosphorus uptake. Results showed that biochar significantly boosted soil available phosphorus (AP) by releasing soluble phosphorus, raising soil pH, reducing phosphorus fixation by iron and aluminum oxides, and enhancing soil cation exchange capacity (CEC) to promote phosphorus dissolution and transformation. Notably, biochar increased the proportion of NaOH-P, facilitating phosphorus accumulation in peanut grains and improving the phosphorus harvest index and utilization efficiency. Straw-returning primarily elevated soil AP by promoting organic phosphorus mineralization and inorganic phosphorus release; however, its acidification of the soil impaired phosphorus translocation to grains, resulting in lower phosphorus-use efficiency compared to biochar. Pig manure compost reduced soil phosphorus fixation and increased soil total organic carbon (TOC), thereby boosting phosphorus transformation. Despite enhancing phosphorus dry-matter production in plants, most phosphorus remained in stems and leaves, with limited translocation to grains, leading to lower phosphorus-use efficiency than biochar. In conclusion, biochar was most effective in enhancing soil phosphorus availability and crop phosphorus-use efficiency, highlighting its potential in sustainable soil fertility management and optimized crop production. Full article

The bacterial diversity of soils cultivated with avocado (Persea americana M.) is influenced by different factors, perhaps the most decisive being the type of agronomic management used by farmers. In conventional agronomic management (CM), high doses of agrochemicals are applied, in contrast to organic agronomic management (OM), where organic fertilizers are used. This alters the diversity and abundance of soil microorganism populations, which in turn affects crop health. This study aimed to isolate and morphologically characterize rhizospheric bacteria from avocado trees under different agronomic management systems (CM and OM). For the bacterial isolates, their ability to promote plant growth in vitro was determined through biochemical tests for phosphorus and calcium solubilization and nitrogen fixation. In addition, their in vivo effect on tomato (S. lycopersicum) growth was evaluated, and their antagonistic capacity against Fusarium sp. was assessed. The results showed differences in the quantity, diversity, and morphologies of bacterial isolates depending on the type of agronomic management. A higher Shannon diversity index was found in OM (2.44) compared to CM (1.75). A total of 35 bacterial isolates were obtained from both management types. A greater number of isolates from OM soils exhibited in vitro PGP activity; notably, eight isolates from OM plots showed phosphate-solubilizing activity, compared to only one from CM plots. Furthermore, although all isolates demonstrated nitrogen fixing capacity, those from OM orchards produced significantly higher nitrate levels than the control (Azospirillum vinelandii). On the other hand, inoculation of tomato plants with bacterial isolates from OM soils increased plant height, root length, and total fresh and dry biomass compared to isolates from CM soils. Likewise, OM isolates exhibited greater antagonistic activity against Fusarium sp. These findings demonstrate the impact of agronomic management on soil bacterial populations and its effect on plant growth and protection against pathogens. Full article

Salinity is a major abiotic stress limiting black gram (Vigna mungo) productivity, particularly in arid and semi-arid regions. Saline soils negatively impact plant growth, nodulation, nitrogen fixation, and yield. This study evaluated the efficacy of co-inoculating salt-tolerant plant growth-promoting bacteria Paenibacillus sp. SPR11 and Bradyrhizobium yuanmingense PR3 on black gram performance under saline field conditions (EC: 8.87 dS m⁻¹; pH: 8.37) with low organic carbon (0.6%) and nutrient deficiencies. In vitro assays demonstrated the biocontrol potential of SPR11, inhibiting Fusarium oxysporum and Macrophomina phaseolina by 76% and 62%, respectively. Germination assays and net house experiments under 300 mM NaCl stress showed that co-inoculation significantly improved physiological traits, including germination rate, root length (61.39%), shoot biomass (59.95%), and nitrogen fixation (52.4%) in nitrogen-free media. Field trials further revealed enhanced stress tolerance markers: chlorophyll content increased by 54.74%, proline by 50.89%, and antioxidant enzyme activities (SOD, CAT, PAL) were significantly upregulated. Electrolyte leakage was reduced by 55.77%, indicating improved membrane stability. Agronomic performance also improved, with co-inoculated plants showing increased root length (7.19%), grain yield (15.55 q ha⁻¹; 77.04% over control), total biomass (26.73 q ha⁻¹; 57.06%), and straw yield (8.18 q ha⁻¹). Pod number, seed count, and seed weight were also enhanced. Nutrient analysis showed elevated uptake of nitrogen, phosphorus, potassium, and key micronutrients (Zn, Fe) in both grain and straw. To the best of our knowledge, this is the very first field-based report demonstrating the synergistic benefits of co-inoculating Paenibacillus sp. SPR11 and Bradyrhizobium yuanmingense PR3 in black gram under saline, nutrient-poor conditions without external nitrogen inputs. The results highlight a sustainable strategy to enhance legume productivity and resilience in salt-affected soils. Full article

Background: Developments in biology, genetics, soil science, plant breeding, engineering, and agricultural microbiology are driving advances in soil microbiology and microbial biotechnology. Material and methods: The literature for this review was collected by searching leading scientific databases such as Embase, Medline/PubMed, Scopus, and Web of Science. Results: Recent advances in soil microbiology and biotechnology are discussed, emphasizing the role of microorganisms in sustainable agriculture. It has been shown that soil and plant microbiomes significantly contribute to improving soil fertility and plant and soil health. Microbes promote plant growth through various mechanisms, including potassium, phosphorus, and zinc solubilization, biological nitrogen fixation, production of ammonia, HCN, siderophores, and other secondary metabolites with antagonistic effects. The diversity of microbiomes related to crops, plant protection, and the environment is analyzed, as well as their role in improving food quality, especially under stress conditions. Particular attention was paid to the diversity of microbiomes and their mechanisms supporting plant growth and soil fertility. Conclusions: The key role of soil microorganisms in sustainable agriculture was highlighted. They can support the production of natural substances used as plant protection products, as well as biopesticides, bioregulators, or biofertilizers. Microbial biotechnology also offers potential in the production of sustainable chemicals, such as biofuels or biodegradable plastics (PHA) from plant sugars, and in the production of pharmaceuticals, including antibiotics, hormones, or enzymes. Full article

Cover cropping has emerged as a pivotal sustainable agronomic practice aimed at enhancing soil health and sustaining crop productivity. To quantify its effects across diverse agroecosystems, we conducted a meta-analysis of 1877 paired observations from 114 studies (1980–2025) comparing cover cropping with bare fallow during fallow periods in major cereal systems across China. Cover cropping significantly reduced soil bulk density by 6.1% and increased key soil nutrients including total nitrogen (+13.1%), total phosphorus (+15.6%), hydrolysable nitrogen (+9.3%), available phosphorus (+11.1%), available potassium (+12.4%), soil organic matter (+11.7%), and microbial biomass carbon (+41.1%). Leguminous cover crops outperformed non-legumes in enhancing nitrogen availability, reflecting biological nitrogen fixation. Mixed-species cover crop mixtures showed superior benefits over monocultures, likely due to complementary effects on nutrient cycling and soil structure. Soil texture and initial soil organic carbon significantly moderated these outcomes. Furthermore, although overall soil pH remained stable, cover cropping exhibited a clear buffering effect, tending to regulate soil pH toward neutrality. Meta-regression analyses revealed a diminishing positive effect on total nitrogen (TN), available potassium (AK), and microbial biomass carbon (MBC) with an extended duration of cover cropping, suggesting potential saturation effects. These results underscore the context-dependent efficacy of cover cropping as a strategy for soil quality enhancement. Optimizing cover crop implementation should integrate the consideration of inherent soil characteristics, baseline fertility, and species composition to maximize agroecosystem resilience and sustainability. Full article

Microbial functional genes serve as the core genetic foundation driving microbial ecological functions; however, its microbial functional gene composition across varied habitats and its ecological adaptation interplay with plants remain understudied. In this study, we investigated the P. tabuliformis rhizosphere microbial functional genes which are related to N and P cycles across ridge and slope habitats between different elevational gradients, analyzed their composition and abundance, and analyzed their responses to environmental factors. Results showed that slope habitats had a significantly greater abundance of N and P cycling functional genes compared to those of ridge counterparts (p < 0.05). Specifically, slope environments showed an enhanced gene abundance associated with denitrification, nitrogen fixation, nitrification, assimilatory/dissimilatory nitrate reduction, and nitrogen transport processes, along with the superior expression of genes related to inorganic/organic phosphorus metabolism, phosphorus transport, and regulatory gene expression. These nutrient cycling gene levels were positively correlated with soil nutrient availability. Our findings revealed distinct ecological strategies: Ridge communities employ resource-conservative tactics, minimizing microbial investments to endure nutrient scarcity, whereas slope populations adopt competitive strategies through enriched high-efficiency metabolic genes and symbiotic microbial recruitment to withstand resource competition. Full article

Soil salinization severely impacts plant cultivation. Lilium pumilum (L. pumilum) exhibits tolerance to saline–alkali stresses. One Bacillus cereus strain, LpBc-47, possesses the ability of growth promotion and saline–alkali tolerance. The microbial diversity of L. pumilum was assessed through metagenomic sequencing. LpBC-47 obtained from L. pumilum was subjected to physiological and biochemical analyses and whole-genome sequencing. The effects of endophytic bacteria on plants were evaluated by measuring growth parameters, physiological indices, antioxidant enzyme activities, and ROS content. Microbial diversity analysis revealed that the abundance of endophytic bacteria in L. pumilum decreased under saline–alkali conditions, whereas the abundance of Bacillus cereus increased. Physiological and biochemical analysis showed that LpBC-47 has the characteristics of promoting growth and reducing plant damage caused by salt–alkali stress, such as phosphorus solubilization, nitrogen fixation, siderophore production, IAA, and ACC deaminase synthesis. Genomic analysis revealed that LpBC-47 contains growth-associated and stress-alleviation genes. GFP indicated the colonization of LpBc-47 in the roots and bulbs of L. pumilum. The LpBc-47 inoculant plant increased leaf length and dry weight, elevated proline and chlorophyll levels, enhanced antioxidant enzyme activity, and reduced oxidative damage. This study highlights the potential of LpBc-47 for improving plant growth under saline–alkali conditions. Full article

Aiming to address a series of problems caused by inefficient nitrogen fixation in soybean within the maize–soybean rotation system under cold-region conditions in Heilongjiang Province, China—such as reduced crop yields, declining soil fertility, and increased dependence on chemical fertilisers—this study investigated the partial substitution of chemical nitrogen fertilisers with bio-organic fertilisers at replacement rates of 10%, 20%, and 30% during soybean cultivation. The treatments included bio-organic fertilisers (OB1, OB2, OB3), inactivated bio-organic fertilisers (O1, O2, O3), Bacillus subtilis (B1, B2, B3), and a control (CK) with the conventional application of chemical fertilisers. In the rotational maize cropping phase, a 50% nitrogen reduction was applied. The results showed that replacing 20% of soybean nitrogen fertiliser with bio-organic fertiliser (OB2 treatment) yielded the most significant increase in productivity and economic return. Compared with CK, the OB2 treatment increased soybean yield by 26.56%, maize yield by 26.69%, and nitrogen fertiliser use efficiency by 3–5%. According to the GRA-TOPSIS model, the OB2 treatment demonstrated the greatest capacity to improve quality and efficiency in the maize–soybean rotation system. At the soybean maturity stage, the OB2 treatment increased soil total organic carbon, available phosphorus, and soil protease activity by 25.36%, 22.20%, and 87.50%, respectively, compared with CK. At maize maturity, soil ammonium nitrogen and soil protease activity increased by 80.24% and 62.47%, respectively. Bio-organic fertilisers combine the benefits of organic fertiliser substrates with those of functional microorganisms. Correlation, cluster, and interaction analyses revealed that the synergistic mechanisms between maize–soybean rotation and bio-organic fertilisers in cold regions are primarily reflected in improved soil quality, enhanced nutrient cycling efficiency, increased nitrogen fixation in soybean root nodules, stimulated microbial activity, and greater resilience to environmental stress. Sustainable agricultural production in cold regions can be achieved through the integrated functioning of these system components. This study provides a theoretical basis for enhancing yield and efficiency in maize–soybean rotation systems under cold climatic conditions. Full article

Tropical acidic soils exhibit inherently low fertility and reduced microbial activity, driven by low pH and accelerated organic matter mineralization, phosphorus (P) fixation, and aluminum (Al³⁺) and iron (Fe³⁺) toxicity. These constraints limit agricultural productivity, necessitating sustainable and low-cost soil amendments essential for improving the soil fertility in such regions. This study investigated the effects of biochar, kitchen stove ash (KSA), and their combined application on the soil chemical properties, nutrient dynamics, and microbial functions in a tropical acidic soil. The treatment included the unamended control and two doses of 0.25% w/w (B₁₀) and 0.5% w/w (B₂₀) corncob biochar, 0.03% w/w kitchen stove ash (A_sh), and 0.027% w/w commercial-grade calcium carbonate (L_ime). Each biochar dose was added alone or in combination with either ash (A_sh + B₁₀ and A_sh + B₂₀) or calcium carbonate (L_ime + B₁₀ and L_ime + B₂₀). After eight weeks of laboratory incubation at 20 °C, the soil pH, N and P bioavailability, microbial biomass, and extracellular enzyme activities were measured. The combined application of 0.5% w/w biochar with 0.03% w/w KSA (A_sh + B₂₀) resulted in the most significant improvements in all of the examined soil fertility indicators than the individual amendments. Specifically, the soil pH was increased by 40% (+1.9 pH units) compared with the unamended control. Available phosphorus, mineral nitrogen, and total potassium were increased by 49%, 22%, and 36%, respectively, compared with the unamended control. Regarding the microbial parameters, the A_sh + B₂₀-treated soil showed the highest microbial respiration (+56%), microbial biomass (+45%), and extracellular C- and N-cycling enzyme activities compared with the unamended soil. The ash supplied minerals (P, K, and Mg) provided a more beneficial effect on the soil’s nutrient content and microbial functions than the calcium carbonate. The study demonstrated that underutilized kitchen ash may supplement biochar’s liming and nutrient supply potentials, even at a lower application rate, to improve the fertility of weathered acidic soil. Full article

3,4-dimethylpyrazole (DMPZ), when used as a nitrification inhibitor, exhibits volatility, poor thermal stability, high production costs, and limited functionality restricted to nitrogen fixation. To address these limitations and introduce novel phosphorus-solubilizing and soil-loosening abilities, herein, a poly (acrylamide-co-acrylic acid)-encapsulated NI (P(AA-co-AM)-e-NI) is synthesized by incorporating linear P(AM-co-AA) macromolecular structures into NI systems. The P(AA-co-AM)-e-NI demonstrates an obvious phase transition from a glassy state to a rubbery state, with a glass transition temperature of ~150 °C. Only 5 wt% of the weight loss occurs at 220 °C, meeting the temperature requirements of the high-tower melt granulation process (≥165 °C). The DMPZ content in P(AA-co-AM)-e-NI is 1.067 wt%, representing a 120% increase compared to our previous products (0.484 wt%). P(AA-co-AM)-e-NI can effectively reduce the abundance of ammonia-oxidizing bacteria and prolong the duration during which nitrogen fertilizers exist in the form of ammonium nitrogen. It can also cooperatively enhance the conversion of insoluble phosphorus into soluble phosphorus in the presence of ammonium nitrogen (NH₄⁺-N). In addition, upon adding P(AA-co-AM)-e-NI into soils, soil bulk density and hardness decrease by 9.2% and 10.5%, respectively, and soil permeability increases by 10.5%, showing that it has a good soil-loosening ability and capacity to regulate the soil environment. Full article

The overuse of inorganic phosphate fertilizers in soils has led to the transfer of inorganic phosphorus (Pi) to aquatic ecosystems, resulting in eutrophication. Adsorption–desorption studies in batch systems were used to evaluate the effect of adding 1% zinc oxide (ZnO) engineered nanoparticles (ENPs) on Pi retention in Ultisol, and Mollisol soils. The 1% ZnO–ENPs showed increased chemical properties such as pH, electrical conductivity, and organic matter content, and reduce nutrient bioavailability (P, N, and Zn), and physical properties such as surface area and pore size of the two soils. The kinetic data of Pi adsorption on Ultisol, Mollisol, Ultisol + 1% ZnO–ENP, and Mollisol + 1% ZnO–ENP systems fitted well to the pseudo-second-order model (r² ≥ 0.942, and χ² ≤ 61), and the Elovich model (r² ≥ 0.951, and χ² ≤ 32). Pi adsorption isotherms for the Ultisol soil adequately fitted to the Freundlich model (r² = 0.976, and χ² = 16), and for the Mollisol soil, the Langmuir model (r² = 0.991, and χ² = 3) had a better fit to the data. With 1% ZnO–ENPs, the linear, Langmuir, and Freundlich models correctly described the Pi adsorption data. Pi desorption was reduced in the Ultisol compared to the Mollisol soil, and with 1% ZnO–ENPs further decreased Pi desorption in both soils. Therefore, ENPs can be used as a new alternative material for Pi fixation in agricultural soils and contribute to mitigating eutrophication issues of aqueous systems. Full article

Hippophae rhamnoides (family Elaeagnaceae) is a deciduous shrub that has become a uniquely advantageous species in the arsenic sandstone area of Inner Mongolia due to its well-developed root system and strong tillering ability. This study, by taking 10-year-old H. rhamnoides in the arsenic sandstone area as the research object and analyzing the morphological traits of their fine roots and their coordination within soil under different stubble heights (0, 10, 15, and 20 cm) and non-stubble treatment, aims to select the optimal stubble height that is most conducive to the rejuvenation of H. rhamnoides and thus improve the decline in the productivity of H. rhamnoides in this region. The results reveal significant differences in fine root and soil properties under different stubble heights (p < 0.05). Among different traits, fine root area density shows the highest total coefficient of variation, making it the most sensitive trait. Principal component analysis results indicate that after stubble treatment, the traits of H. rhamnoides fine roots center on high specific surface area (0.316) + high specific root length (0.312), shifting toward a resource-acquisition ecological strategy with the best foraging efficiency observed under a stubble height of 15 cm. Soil N:P and C:P can explain 66% and 61% of the root morphological traits strategies deployed during stubble treatment, respectively. Fine roots exhibit high adaptability to the breaking of phosphorus limitation and fixation of carbon and nitrogen. Full article

Chemical phosphorus (P) fertilizer is often overused in arid regions with alkaline soils due to soil fixation. Fulvic acid (FA) can increase soil P availability, enhancing crop yield and P use efficiency, but its interaction with P fertilization rates and potential to reduce P fertilizer application remains unclear. A 2-year (2019–2020) field experiment was conducted in Xinjiang, China, to study the impact of FA addition (45 kg ha⁻¹) on cotton yield and P use efficiency under different P fertilization rates (0, 50, 100 and 150 kg P₂O₅ ha⁻¹). Our results showed that P fertilization significantly enhanced cotton biomass, P uptake and seed cotton yields by 17–37%, but the partial nutrient balance (PNB), agronomic efficiency (AE) and partial factor productivity (PFP) decreased with increasing P fertilization rates. FA addition did not change cotton biomass and P uptake, but significantly enhanced seed cotton yield, AE and PFP by increasing bolls per plant. No significant interactions between FA addition and P fertilization rates were observed for cotton biomass, P uptake, seed cotton yield and P use efficiencies. These findings suggest that FA can improve cotton productivity, AE and PPF of P fertilizers, helping to keep the P balance in the cotton field. Full article

Field experiments spanning five years were conducted to convert barren mountainous land into apple orchards, testing five phosphorus (P) fertilization schemes: no inorganic P (NP0K), superphosphate (FP), water-soluble inorganic P (WSF), superphosphate with alkaline soil conditioner (SC), and superphosphate with grass interplanting (GC). Fertilizer solubility and soil pH were found to significantly impact P leaching and accumulation. Among the schemes, WSF exhibited the highest P leaching loss (3.65–3.87%), while SC (2.17–2.79%) and GC (2.79–3.25%) minimized such losses. As soil pH declined over time, aluminum P (Al-P) replaced calcium P (Ca-P) as the dominant inorganic P fraction, while occluded P (O-P) increased, resulting in reduced P bioavailability. Soil organic carbon (SOC) and acid phosphatase activity positively influenced inorganic P fractions, whereas prolonged orchard establishment decreased fixed inorganic P content. Microbial P cycling genes were less abundant and showed negative correlations with soil nitrate-N, electrical conductivity, available P (Olsen P), and SOC. These findings highlight that grass interplanting with superphosphate (GC) is an optimal strategy to minimize phosphorus leaching, enhance soil phosphorus bioavailability, and reduce environmental risks, making it a sustainable approach for orchard management. Full article