High-yield grass Pennisetum sinese Roxb plantation and organic manure alter bacterial and fungal communities structure in an ecological agriculture farm

Research on the optimal ratio of improved electrolytic manganese residue substrate about Pennisetum sinese Roxb growth effects

Electrolytic manganese slag (EMR) is a solid waste generated in the manganese hydrometallurgy process. It not only takes up significant land space but also contains Mn2+, which can lead to environmental contamination. There is a need for research on the treatment and utilization of EMR. Improved EMR substrate for Pennisetum sinese Roxb growth was determined in pot planting experiments. The study tested the effects of leaching solution, microorganisms, leaf cell structures, and growth data. Results indicated a substrate of 45% EMR, 40% phosphogypsum, 5% Hericium erinaceus fungi residue, 5% quicklime, and 5% dolomite sand significantly increased the available phosphorus content (135.54 ± 2.88 μg·g-1) by 17.95 times, compared to pure soil, and enhanced the relative abundance of dominant bacteria. After 240 days, the plant height (147.00 ± 0.52 cm), number of tillers (6), and aerial dry weight (144.00 ± 15.99g) of Pennisetum sinese Roxb increased by 5.81%, 200%, and 32.58%, respectively. Analyses of leaves and leaching solution revealed that the highest leaf Mn content (46.84 ± 2.91 μg·g-1) being 3.38 times higher than in pure soil, and the leaching solution Mn content (0.66 ± 0.13 μg·g-1) was lowest. Our study suggested P. sinese Roxb grown in an improved EMR substrate could be a feasible option for solidification treatment and resource utilization of EMR.

Synergistic effects of earthworms and cow manure under reduced chemical fertilization modified microbial community structure to mitigate continuous cropping effects on Chinese flowering cabbage

The substitution of chemical fertilizers with organic fertilizers is a viable strategy to enhance crop yield and soil quality. In this study, the aim was to investigate the changes in soil microorganisms, soil chemical properties, and growth of Chinese flowering cabbage under different fertilization treatments involving earthworms and cow manure. Compared with the control (100% chemical fertilizer), CE (30% reduction in chemical fertilizer + earthworms) and CFE (30% reduction in chemical fertilizer + cow dung + earthworms) treatments at soil pH 8.14 and 8.07, respectively, and CFC (30% reduction in chemical fertilizer + cow manure) and CFE treatments increased soil organic matter (SOM), total nitrogen (TN), available nitrogen (AN), and available potassium (AK) contents. Earthworms and cow manure promoted the abundance of Bacillus and reduced that of the pathogens Plectosphaerella and Gibberella. The mantle test revealed that pH was not correlated with the microbial community. Random forest analysis verified that AN, SOM, and TN were important factors that jointly influenced bacterial and fungal diversity. Overall, the synergistic effect of earthworms and cow manure increased soil fertility and microbial diversity, thereby promoting the growth and development of Chinese flowering cabbage. This study enhanced the understanding of how bioregulation affects the growth and soil quality of Chinese flowering cabbage, and thus provided a guidance for the optimization of fertilization strategies to maximize the yield and quality of Chinese flowering cabbage while reducing environmental risks.

Date Palm Waste Compost Application Increases Soil Microbial Community Diversity in a Cropping Barley (Hordeum vulgare L.) Field

Application of date palm waste compost is quite beneficial in improving soil properties and crop growth. However, the effect of its application on soil microbial communities is less understood. High-throughput sequencing and quantitative real-time PCR (qPCR) were used to evaluate the effect of compost application on the soil microbial composition in a barley field during the tillering, booting and ripening stages. The results showed that compost treatment had the highest bacterial and fungal abundance, and its application significantly altered the richness (Chao1 index) and α-diversity (Shannon index) of fungal and bacterial communities. The dominant bacterial phyla found in the samples were Proteobacteria and Actinobacteria while the dominant fungal orders were Ascomycota and Mortierellomycota. Interestingly, compost enriched the relative abundance of beneficial microorganisms such as Chaetomium, Actinobacteriota, Talaromyces and Mortierella and reduced those of harmful microorganisms such as Alternaria, Aspergillus and Neocosmospora. Functional prediction based on Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) showed that amplicon sequence variant (ASV) sequences related to energy metabolism, amino acid metabolism and carbohydrate metabolism were associated with compost-treated soil. Based on Fungi Functional Guild (FUNGuild), identified fungi community metabolic functions such as wood saprotroph, pathotroph, symbiotroph and endophyte were associated with compost-treated soil. Overall, compost addition could be considered as a sustainable practice for establishing a healthy soil microbiome and subsequently improving the soil quality and barley crop production.

Quinone redox cycling drives lignocellulose depolymerization and degradation in composting environments based on metagenomics analysis

In this study, the effect of Fe³⁺ on the quinone redox cycling driving lignocellulosic degradation in composting systems was investigated. The results showed that the degradation rates of cellulose, hemicellulose, and lignin were higher in the experimental group (CT) with Fe₂(SO₄)₃ addition than in the blank group (CK) (CT, 52.55 %, 45.14 %, 56.98 %; CK, 49.63 %, 37.34 %, 52.3 %). Changes in the abundance of key enzymes for quinone reduction (AA3_1, AA3_2, AA6) and the structural succession of microbial communities were analyzed by metagenomic analysis. Among them, Fe₂(SO₄)₃ had the most significant effect on AA3_2, with an approximately 8-fold increase in abundance compared to the beginning of composting. The dominant phylum in the composting process was Actinobacteria. In conclusion, the addition of Fe₂(SO₄)₃ contributed to the quinone redox cycling and effectively improved the degradation rate of lignocellulose in composting.

Characteristics of bacterial and fungal communities and their impact during cow manure and agroforestry biowaste co-composting

Microbial communities and environmental conditions are both of great importance for efficient utilization of agroforestry resources. Nevertheless, knowledge about the role of soluble nutrients and enzymatic properties, and their inner links with microbial communities remain limited. This is especially the case for the co-composting of agricultural and forestry biowaste. Here, we investigate the succession of key microbes during co-composting (sawdust + cow manure, SA; straw + cow manure, ST), employing amplicon sequencing, enzyme assays, and physicochemical analyses. N-fixing bacteria (Pseudomonas) and C-degrading fungi (Acaulium) have been identified as dominant taxa during such co-composting. Although eight antibiotic resistance genes were found to persist during composting, pathogenic microbes declined with composting time. NO₃^--N content was screened as a determinant structuring the bacterial and fungal communities, with importance also shown for C-degrading enzymes such as cellulose, laccase, and peroxidase activity. These results identify the key microbial taxa and their main interactive environmental factors, which are potentially valuable for the development of a mixed microbial inoculant to accelerate the maturation of agroforestry biowastes composting.

Fusarium oxysporum Associated with Fusarium Wilt on Pennisetum sinese in China

Pennisetum sinese, a versatile and adaptable plant, plays an essential role in phytoremediation, soil reclamation, and fodder production. From 2018 to 2021, the occurrence of Fusarium wilt, with symptoms of foliar blight and internal discoloration of the stem, was observed in Chongqing, China. Pathogens were isolated from the symptomatic leaves. Based on morphological characteristics as well as DNA sequences of the 18S ribosomal RNA (SSU), translation elongation factor 1-α (EF1-α), RNA polymerase II subunit 1 (rpb1), and RNA polymerase II second largest subunit (rpb2) genes, the causal agents were identified as Fusarium oxysporum. Phylogenetic analysis of the combined dataset of EF1-α, rpb1 and rpb2 showed that pathogenic isolates clustered with F. oxysporum strains. The pathogen was reisolated from inoculated and diseased tissues; thus, Koch’s postulates were fulfilled. This is the first report of F. oxysporum causing Fusarium wilt on P. sinese in China and worldwide.