The natural bacterial communities of the soil–plant system are relevant in the process of suppressing diseases caused by soilborne plant pathogens. However, little is known regarding the structure of these communities in soils cultivated with brassica vegetables and their relationship with clubroot severity, a disease caused by Plasmodiophora brassicae. In the present study, the composition of bacterial communities in soils cultivated with cauliflower with distinct levels of disease severity was compared. The bacterial composition in soils with lower and higher clubroot severity differs in phylum and genera levels. Soils associated with plants with lower disease severity showed predominance of Kaistobacter, Flavisolibacter, Sphingobacterium, Koribacter, Nitrospira, Bradyrhizobium and Bacillus. Our study reinforces the importance of management strategies that promote improving the physical–chemical characteristics of soil, which are essential to modulate bacterial populations correlated with plant disease suppression.
The plastic deformation of sandy soils is poorly understood from a microscopic point of view. The criteria to predict the mode of rupture of shallow foundations are mostly based on phenomenological arguments and may fail to explain the results obtained experimentally in model foundations. This work validates a model to determine the mode of rupture of sandy soils underlying shallow foundations based on the assumption that the complex rupture behavior of sand may be described approximately as a trade-off between the energy dissipation in a sand slip and the subsequent reduction of elastic potential energy in the surrounding sand mass. This theoretical framework describes more accurately experimental results found in the literature than the approach based on the rigidity index of the soil. In order to extrapolate results from small-size model experiments to large-size foundations, direct dimensional arguments may be used, since the proposed account of the failure mechanism is based on the laws of mechanics, not on phenomenological equations.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.