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Biochar (Bc) and liquid vermicompost extracts (LVEs) are increasingly being used as biofertilizers in agriculture to promote soil-microbe-crop interactions. However, although both these products can potentially act synergistically due to their complementary characteristics, their co-application in different soils has not yet been investigated. Therefore, firstly, an LVE-activated biochar (BLVE) was experimentally formulated and the persistence of LVE bacteria over a 60-day storage period was determined. The total number of LVE bacteria increased by 10-fold after 7 days and was stable throughout the entire biochar storage period. In addition, changes in the composition of the bacterial community were observed after 30 days of storage, indicating that taxa less represented in pure LVE may be advantaged upon biochar colonization. Secondly, a microcosm experiment was performed to evaluate whether the biological fertility and enzyme activities of two soils, differing in organic matter content, could be enhanced by the addition of LVE-activated biochar. In this experiment, three different doses of Bc, LVE, and BLVE against the carbon-related biological fertility index (i.e., biological fertility index, BFI) and three enzyme activities over a 21-day incubation period were tested. The BLVE treatment yielded the best results (i.e., BFI +32%, enzyme activities +38%). This indicates that Bc and LVEs can act synergistically to promote soil fertility, quality, and microbial activity. By integrating LVE-activated biochar into their soil management practices, farmers could achieve higher crop yields and healthier products. [ABSTRACT FROM AUTHOR]

Soil food webs are extremely complex as they contain diverse organisms. Feeding preference, also known as prey selection, is an important determinant of soil community compositions. However, the feeding preferences of nematodes are commonly ignored in ecology research. In this paper, the population dynamics and feeding preferences of three bacterial-feeding nematodes (i.e., Caenorhabditis elegans, Protorhabditis spp., and Acrobeloides spp.) for eight bacterial prey species were evaluated. Protorhabditis and Acrobeloides were isolated from a paddy soil in subtropical China. C. elegans, the most common model system for biological research, was used as a control in this study, and it was revealed that C. elegans could feed on all the eight bacteria strains. Protorhabditis could only survive when fed E. coli and Bacillus thuringiensis. Acrobeloides could only survive when fed E. coli and B. aryabhattai. During 10 days of culture, C. elegans populations reached the maximum in 5–7 days, and most C. elegans populations exceeded 10,000 individuals. The two Protorhabditis populations on E. coli and Bacillus thuringiensis included less than 800 individuals during 10 days of culture. Acrobeloides population on B. aryabhattai reached the maximum (7799 individuals) on day 8, while on E. coli was its population included less than 500 individuals. These results indicate that different nematode species indeed have distinct feeding preferences. In addition, the population dynamics of the two soil nematodes isolated from soil could not fully match with their inferred life-history strategies (i.e., cp values, and a 1-5 colonizer-p-ersister series that range from r-strategists to K-strategists). Our findings highlights the existing deficiencies in the understanding of the feeding behavior and the life-history strategies of soil nematodes. [ABSTRACT FROM AUTHOR]

Compost tea is a liquid organic amendment that has been reported to benefit plant growth and performance through positive effects on microbial communities and plant nutrition. However, few studies have demonstrated this for containerized plants produced in tree nurseries. Five common urban tree species (Acer negundo, Corymbia maculata, Ficus platypoda, Hymenosporum flavum, Jacaranda mimosifolia) were grown in a containerized experiment to investigate the effects of compost tea application on tree growth and root mycorrhizal colonization over six months. The microbial composition of compost tea was also determined with 16S (bacteria) and ITS1 (fungi) metabarcoding. No significant positive effect of compost tea on plant growth or root mycorrhizal colonization was observed. Roots of all tree species were colonized by one type of mycorrhizal fungi, ectomycorrhizae (ECM), or vesicular–arbuscular mycorrhizae (VAM). However, no relationship between the mycorrhizal colonization percentage and plant growth was detected. Thus, there was no evidence that a once-off application of compost tea had benefits for mycorrhizal colonization and growth of containerized trees in a nursery setting. Further research is needed to investigate whether any benefit from compost tea is evident once containerized trees are planted into urban landscapes where growth conditions may be more challenging. [ABSTRACT FROM AUTHOR]

There is a growing focus on the production of biochar from organic wastes and its forestry use. However, it is unclear how applying biochar pyrolyzed at different temperatures influences both soil bacterial and fungal communities. In this study, two kinds of biochar were pyrolyzed at 350 °C and 600 °C, from poplar sawdust, and then applied as an auxiliary substrate material (15% addition by volume) for the container seedling cultivation of Cyclocarya paliurus, a native timber and medically used tree species, to compare the response of the soil's microbial traits. The results showed that after 5 months of cultivation, the addition of the biochar application improved the soil's physical and chemical properties to a certain extent by decreasing its bulk density and increasing its field water-holding capacity, pH and organic carbon content. The soil's pH and content of organic C, available N and available P were significantly higher in the substrate with the addition of the biochar pyrolyzed at 600 °C (Bioc600) than in that of the substrate with added pyrolyzed biochar at 350 °C (Bioc350). The biochar application also enhanced the soil's microbial N (MBN) but showed no changes in the MBC/MBN ratio. The biochar application had no effect on the diversity and composition of the soil's bacterial community, but showed a certain effect on its fungal community composition and had different influences between low and high pyrolysis temperatures. The relative abundance of several of the dominant fungal phyla and genera increased with the addition of biochar due to the increase in the soil's pH when compared to the CK (no biochar or sawdust addition). When compared with Bioc350, the dominant phylum Basidiomycota and genus Vanrija further increased in abundance with Bioc600. These findings reveal the consistent effects of biochar pyrolysis temperature and demonstrate the different regulatory roles of biochar application in soil bacterial and fungal communities, providing valuable information on how biochar can effectively be used as a substrate for seedling cultivation. [ABSTRACT FROM AUTHOR]

The global sustainability agenda is increasing the demand for reduction in inputs into agricultural production while maintaining profitable yield of quality products. Plant diseases are a major constraint for both yield and product quality, but often tools for their control are ineffective or lacking. Biological control using antagonistic microorganisms has long been a subject of research resulting in a wide range of products that are now available and marketed in specific territories around the world. These preparations are often niche products with narrow uses. The research effort is intense both to develop new biological control agents (BCAs) and to obtain knowledge of the mechanisms underlying biological disease control. The prospects for biological control are promising. As a minimum, BCAs supplement other sustainable disease management practices such as disease resistance, and present opportunities for controlling diseases for which other approaches are ineffective or unavailable. We can realistically expect increasing use of BCAs to control crop diseases in ways that will benefit the environment. This review paper arose from a webinar held by the British Society for Plant Pathology as part of the International Year of Plant Heath (IYPH2020), at which many of the 300 participants posed or discussed interesting questions. This review is based on that input and the panel members at the webinar are all included as co‐authors in this review. [ABSTRACT FROM AUTHOR]

Summary: Bacteria can regulate cell morphology in response to environmental conditions, altering their physiological and metabolic characteristics to improve survival. Conditional filamentation, in which cells suspend division while continuing lateral growth, is a strategy with a range of adaptive benefits. Here, we review the causes and consequences of conditional filamentation with respect to bacterial physiology, ecology and evolution. We describe four major benefits from conditional filamentation: stress tolerance, surface colonization, gradient spanning and the facilitation of biotic interactions. Adopting a filamentous growth habit involves fitness trade‐offs which are also examined. We focus on the role of conditional filamentation in soil habitats, where filamentous morphotypes are highly prevalent and where environmental heterogeneity can benefit a conditional response. To illustrate the use of information presented in our review, we tested the conditions regulating filamentation by the forest soil isolate Paraburkholderia elongata 5NT. Filamentation by P. elongata was induced at elevated phosphate concentrations, and was associated with the accumulation of intracellular polyphosphate, highlighting the role of filamentation in a phosphate‐solubilizing bacterium. Conditional filamentation enables bacteria to optimize their growth and metabolism in environments that are highly variable, a trait that can impact succession, symbioses, and biogeochemistry in soil environments. [ABSTRACT FROM AUTHOR]