Biology and Fertility of Soils最新文献

Lime application (liming) has historically been used to ameliorate soil acidity in grasslands. Liming effectively improves soil pH, plant productivity, and soil physicochemical properties, but the long-term impact of acidity control by liming on key microbial nitrogen (N)-cycling genes in semi-natural grasslands is unknown. We investigated the effect of 65 years of liming on N-cycling processes in the limed and control plots of the Ossekampen long-term grassland experiment in the Netherlands. These plots have not received any other fertilizers for 65 years. Soil sampling and nitrous oxide (N₂O) emission measurements were conducted three times in spring and four times in summer, and quantitative real-time PCR was performed to determine the absolute abundances of N-cycling genes, including ammonia-oxidation (amoA-AOB, amoA-AOA, amoA-comammox), denitrification (nirS, nirK, nosZ), nitrate ammonification (nrfA), and N-fixation (nifH) genes. Long-term liming increased the absolute abundances of nitrifiers, denitrifiers, and nitrate ammonifiers. Soil N₂O emissions did not differ significantly between liming and control treatments. Additionally, liming had a buffering effect that maintained the population of N-cycling microbes against seasonal variations in abundance. Our results indicate that improving soil acidity through liming potentially facilitates microbial N-cycling processes without increasing N₂O emissions.

Understanding the interaction between microbes and soil nutrients during fertilization is crucial for improving plant fruit quality. However, the impact of soil mineral elements, and their interactions with microbial communities on plant performance remain unclear. In this study, we combined fruit and soil mineral analyses with microbial community resistance assessments in an 8-year watermelon continuous cropping system to investigate the microbiome-mediated plant responses to organic and bio-organic fertilizations. Our results showed that bio-organic fertilizer (BOF) treatment significantly enhanced watermelon quality, with a quality index 1.62 and 9.29 times higher than organic fertilizer (OF) and the control (CK), respectively. BOF improved soil mineral levels, particularly soil available iron (AFe), which was 1.77 and 4.01 times greater than OF and CK, and leaf iron content, which was 2.10 and 11.49 times higher than OF and CK. BOF also improved the soil microbial resistance and microbial community stability along with a promotion of symbiotic components within soil microbiomes and led to a stable microbial community, which supported enhanced soil nutrient cycling and plant health. Additionally, BOF-associated microbial clusters strongly linked with AFe and watermelon quality index. Stable mineral-solubilizing bacteria like Ammoniphilus, Bacillus, Acidibacter, and Talaromyces were enriched by BOF-treatment, which may have contributed to the dissolution of soil minerals (esp., AFe) and watermelon quality. Overall, our findings revealed a significant role of bio-organic fertilizers in improving soil minerals and crop quality through modulating key soil microbial clusters (e.g., stability and symbiont abundances).

To address the decline in soil organic matter and thus soil life and soil health due to intensive tillage in organic potato production, innovative regenerative farming approaches employ cover crops and transferred dead organic mulch to improve plant nutrition, minimize soil disturbance, and foster soil microbial activity. Starting in 2019 to 2021, three organic two-year field experiments were set up in a field that had been converted to non-inversion tillage since 2015, to investigate the effects of cover cropping before and organic dead mulch application to potatoes compared to weedy fallow and N-fertilization with hair meal pellets as controls. For every experiment, microbial biomass carbon (MBC), basal respiration, and fungal ergosterol were examined, starting with the cover crop in fall before potatoes until the spring in the crop succeeding potatoes. In all three experiments, initial effects on soil microbial activity depended on the incorporated biomass with no differences between vetch-triticale as a cover crop or a weedy fallow. During potato cropping, however, especially the incorporation of the vetch-triticale cover crop combined with the application of grass-clover mulch resulted in increased MBC, basal respiration and ergosterol. After potato cropping, basal respiration and ergosterol were increased in plots with weedy fallow before and mulched with grass-clover during potatoes pointing to a slower and overall more fungal based mulch degradation at that time in those plots. These results underscore the potential of regenerative practices to enhance soil microbiology during potato cultivation.

When imidazolinone herbicides persist longer than intended and remain active in the soil, they can have unknown impacts on soil health. This study investigated the impact of simulated soil residues of an imidazolinone herbicide on shoot dry matter and bacterial communities in the bulk and rhizosphere soil in tolerant and susceptible wheat genotypes, at two different crop growth stages. Four levels of gradient increased herbicide residues were applied, and rhizosphere bacterial diversity and community composition were analysed using 16S rRNA gene amplicon sequencing. Our results highlight that the shift in wheat rhizosphere bacteriome is driven more by the crop growth stage and wheat genotype than the presence and level of imidazolinone residues. Results showed a linear trend of increasing alpha diversity with increasing herbicide residues during the early crop growth stage, and a decrease in alpha diversity with increasing herbicide residues during the late crop growth stage, only for the tolerant genotype. The order Betaproteobacteriales in the rhizosphere was increased by herbicide residues to a greater extent than the other taxonomic groups. During the early growth stage, there were more ASV (amplicon sequence variant) enriched by imidazolinone herbicide residues in the rhizosphere of the tolerant genotype compared with the susceptible genotype. Future research work should consider studies with soils that have different physicochemical properties, and focus on other soil microbes of known significance to nutrient cycling and crop growth.

Pursuing sustainable agricultural production necessitates innovative approaches to enhance nutrient use efficiency and mitigate the environmental impact of fertilizer use in cropping systems. Biochar-based controlled-release fertilizers (BCRFs) have emerged as a promising solution to address these challenges. This paper reviews BCRF production methods, nutrient retention mechanisms, and effects on plant growth and the environment compared with conventional fertilizers. Various techniques have been used to improve the fertilizer efficiency of BCRFs, including impregnation, coating, granulation, co-pyrolysis, hydrothermal synthesis, and in-situ pyrolysis, each offering unique advantages in controlling nutrient release. BCRFs facilitate nutrient retention and gradual release, improving soil nutrient use efficiency. The BCRFs also improve soil structure and enhance microbial activities and root growth, thereby fostering resilient and productive crops. BCRFs have considerable potential for carbon sequestration, mitigation of greenhouse gas emissions, reduction in nutrient leaching and environmental impact, contributing to sustainable agricultural practices compared to the use of conventional fertilizers (e.g., synthetic or chemical fertilizers). However, attention is needed to address challenges concerning the economic feasibility, scalability, and regulatory frameworks associated with using BCRFs. BCRFs offer a promising pathway for improving nutrient management in agriculture; however, interdisciplinary efforts are needed to unlock their full potential in enhancing plant growth and environmental sustainability.

Drought stress is a key factor limiting crop growth and production. Although a variety of crops can improve their survival and drought resistance as a result of interactions with their rhizosphere microbiota, the mechanisms related to plant–rhizosphere microbiota interactions under drought stress are not fully understood, especially regarding the mechanisms in habitats with droughts. Here, the molecular mechanisms involving the E. ulmoides rhizosphere microbiota in response to drought stress were systematically analyzed using pot experiments, metagenomic sequencing, and assessment of plant physiological indexes. The results showed that the composition and co-occurrence patterns of the E. ulmoides rhizosphere microbiota were altered under drought stress, and the phylogenetic diversity of the core microbes was increased. Moreover, Betaproteobacteria and Opitutae were significantly enriched in the rhizosphere and their relative abundances were significantly correlated with the levels of superoxide dismutase (SOD) and soluble sugar (SS) in E. ulmoides. Kyoto Encyclopedia of Genes and Genomes (KEGG) functional analysis showed that two-component system, biosynthesis of amino acids, ABC transporters, and ribosome became more abundant in the rhizosphere under drought stress, and were significantly correlated with SOD and SS levels. Similarly, genes encoding Carbohydrate Active Enzymes (CAZymes) activities that auxiliary activities and glycosyl transferases became more abundant and were significantly correlated with SOD and SS levels. In conclusion, the relative abundances of KEGG functions and CAZymes classes in the E. ulmoides rhizosphere microbiota were altered by enrichment of Betaproteobacteria and Opitutae, which in turn affected the host physiological indexes to improve the host’s adaptability to drought. These findings are of great significance for improving plant drought tolerance in order to increase sustainable crop production.

Among the long-term sustainable solutions to mitigate saline stress on plants, the use of plant growth promoting microorganisms (PGP) is considered very promising. While most of the efforts have been devoted to the selection and use of bacterial PGPs, little has been proposed with yeast PGP (PGPYs). In this study, three PGPY strains belonging to Naganishia uzbekistanensis, Papiliotrema terrestris and Solicoccozyma phenolica were employed singularly and in a consortium to mitigate salt stress of zucchini (Cucurbita pepo). The results demonstrated that these yeasts, when applied to salt-amended soil, mitigated the growth inhibition caused by NaCl. Among the three species, N. uzbekistanensis and P. terrestris showed the most significant improvements in plant performance, with N. uzbekistanensis exhibiting hormetic effects under salt stress by improving root length and dry plant biomass. In general, the root system was the most affected part of the plants due to the presence of the yeasts. The entire rhizosphere bacterial microbiota was significantly influenced by the addition of PGPYs, while the mycobiota was dominated by the introduced yeasts. Metabolomic fingerprinting using FTIR revealed modifications in hemicellulose and silica content, indicating that PGPY inoculation impacts not only the plant but also the soil and rhizosphere microorganisms.

Disease-resistant wheat cultivars exhibited significantly lower infection rates in field conditions, associated with higher microbial diversity in key compartments such as the rhizosphere soil and phylloplane. Microbial community analysis revealed compartment-specific selection effects, with significant horizontal microbial transfers noted across plant tissues, suggesting a strong compartment-dependent selection from soil microbiomes. Further, resistant varieties were enriched of potential beneficial microbial taxa that contribute to plant health and disease resistance from seedling to adult stages. This was verified by rhizosphere microbiome transplantation experiment, where the inoculation of the rhizosphere microbiome of resistant cultivars suppressed pathogen infection and enhanced plant growth, indicating that wheat resistance to soil-borne virus disease depended on the interaction of the host with the microbial community around it. Our results also demonstrated that the microbial composition and network at the seedling stage predicted wheat health and pathogen susceptibility. Disease infection simplified the intra-kingdom networks and increased potentially beneficial taxa such as Massilia, Bacillus, and Pseudomonas within the microbiome. Overall, our findings provide novel insights into the microbial dynamics influenced by host traits and their implications for disease resistance and plant health, offering potential strategies for agricultural biocontrol and disease management.

Bacillus amyloliquefaciens is a widely used plant growth-promoting rhizobacterium. To investigate its role and mechanisms in selenium (Se) biofortification in crops, a pot experiment with four treatments including no application of Se fertilizer and B. amyloliquefaciens (control), B. amyloliquefaciens application (BA), Se fertilizer application (Se), and combined B. amyloliquefaciens and Se fertilizer application (BA + Se) was conducted. The results showed that, BA + Se treatment significantly increased total biomass of tea seedling compared with control, BA and Se treatments. Additionally, compared with Se treatment, BA + Se treatment significantly increased the Se concentrations in root and leaf, and Se content in the whole tea seedling by 101.4%, 34.5%, and 149.5%, respectively; BA + Se treatment also significantly increased the soil exchangeable Se and total available Se concentrations. Compared with control, BA treatment upregulated the expression level of CsPHT1;2b; Se treatment upregulated the expression levels of CsSULTR1;1, CsSULTR1;2, CsPHT1;2a and CsPHT1;2b; BA + Se treatment upregulated the CsSULTR1;1 and CsPHT1;2a expression levels in tea seedling roots. The 16S rRNA indicated that BA and Se treatments had no effects on the diversity of rhizosphere bacterial community, but altered bacterial community composition. Soil pH was the most important environmental factor affecting rhizosphere bacterial community composition. BA + Se treatment significantly increased soil pH and the complexity of rhizosphere bacterial symbiotic network, compared with other three treatments. Furthermore, comparative analysis about rhizosphere soil properties and bacterial community composition and function between Se and BA + Se treatments, suggested that BA + Se treatment promoted soil Se availability by recruiting g_Sinomonas species and regulating the abundance of Se reductase in the rhizosphere.

In this paper a new modeling approach for denitrification and similar processes, which depend on the geochemical gradient between the air-filled larger pores in a soil and a water-filled matrix, is presented. The new modeling approach is capable of taking soil structural properties (obtained e.g. from X-ray CT) into account without requiring a high-resolution simulation. The model approach is explained and its application is demonstrated by simulating denitrification experiments conducted with repacked soil samples to assess the challenges and possibilities of the new approach. The main result of the modeling is that the nitrous oxide emission measured in the experiment can not be explained by a limited supply with oxygen alone at a carbon turnover rate derived from carbon dioxide emissions. It is additionally necessary that the microbial activity is concentrated in localized hot spots to create anaerobic conditions. This is confirmed by analytical solutions.