Sandy soils amended with bentonite induced changes in soil microbiota and fungistasis in maize fields
Citation
Zhang, H., Chen, W., Zhao, B., Phillips, L.A., Zhou, Y., Lapen, D.R., Liu, J. (2020). Sandy soils amended with bentonite induced changes in soil microbiota and fungistasis in maize fields. Applied Soil Ecology, [online] 146 http://dx.doi.org/10.1016/j.apsoil.2019.103378
Plain language summary
Bentonite is mineral clay and often used as soil conditioner to promote sandy soil formation, nutrient, and water retention ability. However, little is known about how bentonite influences soil microbial communities associated with crops, such as maize in continuous production on sandy soils. In this study, we used a metabarcoding approach to characterized the fungal and bacterial communities in sandy maize fields. We found that the fungal communities were dominated by Guehomyces, Alternaria and Mortierella, and were more diverse and abundant in soils amended with bentonite, while the bacterial communities had similar alpha-diversity under both conditions. However, functional bacterial groups that are affiliated with fermentation and N-cycling were quite different under the two treatments. We also discovered that community members were more competitive than cooperative among each other, especially for fungal phytopathogens. In summary, our study showed that the addition of bentonite increased maize productivity and reshaped the microbial functional guilds in sandy soils, a consequence of improved soil structure as well as water and nutrient retention; however, the amendment's long-term impact on soil suppressiveness to fungal phytopathogens is worth further investigation.
Abstract
The addition of bentonite, used as soil conditioner, can promote sandy soil macro-aggregate formation, moisture content retention and increase soil nutrient concentrations. However, there is limited knowledge about how bentonite influences soil microbial communities and interconnections among community members associated with crops, such as maize in continuous production on sandy soils. Metabarcoding analysis of the fungal internal transcribed spacer 1 (ITS1) region and the bacterial 16S rRNA gene V4 region revealed that the fungal communities in sandy maize fields (dominated by Guehomyces, Alternaria and Mortierella) were more diverse and abundant in soils amended with bentonite than those without bentonite amendment. By contrast, the bacterial communities (dominated by Proteobacteria and Actinobacteria) had similar alpha-diversity under both conditions but many functional guilds, including those affiliated with fermentation and N-cycling, differed significantly in community compositional structure between soils with and without bentonite amendment. The increase in soil nutrient concentrations due to the addition of bentonite was a key factor associated with changes in the bacterial communities. However, the fungal communities were more strongly influenced by the capacity of bentonite to increase soil moisture retention and enhance macro-aggregate development. Molecular ecological network analysis revealed more competitive (62.1% of total significant associations) than cooperative (37.9%) associations among microbial community members across all soils studied. The observation that fungal phytopathogens recovered from bentonite-amended soils had more negative correlations (75.6%) with naturally occurring beneficial bacteria and/or fungi than those in non-bentonite soils (65.2%), perhaps suggests, although speculation, that the addition of bentonite promoted soil fungistasis. In summary, our study showed that the addition of bentonite increased maize productivity and reshaped the microbial functional guilds in sandy soils, a consequence of improved soil structure as well as water and nutrient retention; however, the amendment's long-term impact on soil suppressiveness to fungal phytopathogens is worth further investigation.