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Land use affects physical, chemical and biological properties and processes in soil. Long-term field experiments were employed to reveal changes of soil characteristics induced by land use. Using high-throughput 16S rRNA gene amplicon sequencing and quantitative PCR, comparative analyses were conducted on prokaryotic community structure in different soil diagnostic horizons of Chernozems under forest, fallow and arable land within a long-term field experiment established by V.V. Dokuchaev in 1892. Soil organic carbon (SOC) was a more sensitive and reliable indicator of changes than microbial diversity indexes. Verrucomicrobia changed most among different prokaryotic phyla. Long-term tillage did not result in detectable changes in α-diversity of Chernozem prokaryotic communities, except for that plow pan horizon that showed a pronounced decrease in microbial diversity. The differences in prokaryotic community structure between soil horizons were more contrasting than between land uses. Analysis of β-diversity indicated that soil microbial communities at different depths formed non-overlapping clusters of A and B horizons, while microbiomes of transitional AB horizons fall in between these two clusters. The sharp decline in α-diversity in the plow pan horizon, as well as significant differences between the communities of A and B horizons indicate that the soil microbiomes are horizon-specific. [ABSTRACT FROM AUTHOR]

Loss of tropical forests leads both to the loss of aboveground biodiversity and to the changes in belowground biological activity. Planted secondary forests return canopy cover, but the reversibility of belowground changes may depend on soil properties, forest age and tree species composition. We studied microbial communities in an array of soils in southern Vietnam under different vegetation: natural tropical forests, grasslands on deforested area and 20 and 30 years-old forest plantations. Conversion of natural forests into grasslands led to the loss of half of soil organic matter and microbial abundance, soil moisture decreased, bacterial community structure changed and beta-diversity increased. Bacterial alpha-diversity and pH were not affected by deforestation. Reforestation for 30 years restored bacterial and archaeal abundance, partially restored bacterial community structure, but did not restore fungal abundance and organic matter content. Thus, forest planting in southern Vietnam restores soil microbiome properties partially, but the complete restoration apparently requires much more than 30 years of secondary forest succession. [Display omitted] • Deforestation in Southern Vietnam changes soil bacterial community structure. • Deforestation decreases soil moisture, organic matter content and microbial abundance. • Reforestation for 30 years restores soil bacterial community structure and abundance. • Reforestation does not restore soil moisture, organic matter content and fungal abundance. [ABSTRACT FROM AUTHOR]

Biological control of pathogenic Fusarium species through the promotion of detrital food webs is a promising option for agricultural production and could be of high value in organic farming. To obtain quantitative information on the impact of detrital subsidy on the development of Fusarium infection in winter wheat seedlings, we established a 60-day laboratory experiment in which the soil was amended with either a N-poor or a N-rich mixture of straw and compost containing the same amount of organic carbon (200 g C m−2). Compared with the control treatment (no subsidy), shoot biomass decreased by 27% in the N-poor mulch treatment and increased by 24% in the N-rich mulch treatment. For both of the added mulch treatments, the population of mycophagous and predatory mites increased fivefold compared to the control. The abundance of Enchytraeidae also increased in both N-poor (by 68%) and N-rich (by 46%) mulch treatments. Unexpectedly, the abundance of gene copies of total soil fungi and of genus Fusarium in particular, as well as the abundance of Fusarium -specific polysaccharide protein conjugate (FPPC), were not affected by either mulch addition. Nevertheless, wheat seedlings were not infected by Fusarium wilt in either mulch treatment, whereas in the control treatment, the infection incidence was about 9%. The quantitative information obtained here may be important for the development of an ecological control method for cereal diseases caused by pathogenic Fusarium species. [ABSTRACT FROM AUTHOR]