|BAUGHER, CHRISTOPHER - University Of Idaho|
|KAHL, KENDALL - University Of Idaho|
|JOHNSON-MAYNARD, JODI - University Of Idaho|
Submitted to: Soil Biology and Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/6/2020
Publication Date: 10/8/2019
Citation: Schlatter, D.C., Baugher, C., Kahl, K., Johnson-Maynard, J.L., Huggins, D.R., Paulitz, T.C. 2019. Bacterial communities of soil and earthworm casts of native Palouse Prairie remnants and no-till wheat cropping systems. Soil Biology and Biochemistry. 139. https://doi.org/10.1016/j.soilbio.2019.107625.
Interpretive Summary: We explored the bacteria communities of earthworms and soil from Palouse prairie remnants and cultivated dryland wheat systems. We found core bacterial taxa that were more abundant in the prairie than cultivated soil, and unique taxa present in the casts of earthworms from the native sites, compared to the farmed sites. but the casts from agricultural soils were enriched in Pseudomonas and Flavobacterium. Through their casting activity, earthworms appear to enhance the abundance of some of the bacteria species that are already present in the bulk soil, In conclusion, microbial community composition in prairie soils was distinctly different from that in agricultural soils, as were the microbial communities of earthworm casts associated with the different land uses.
Technical Abstract: Earthworms are important ecosystem engineers and modify the physical and chemical properties of soils. However, less is known about how earthworms modify soil microbial communities. We compared bacterial communities of the bulk soil and earthworm casts in native prairie remnants and wheat cropped fields in the Palouse of Eastern Washington. Communities among prairie sites were similar, indicating a consistent prairie community. The bulk soil and earthworm casts of native prairie locations had higher richness compared to agricultural sites, but similar diversity. Diversity tended to be higher in bulk soil than earthworm casts in native prairies but not agricultural soils. In native prairies, earthworm casts were enriched in the families Caulobacteraceae, Cellulomonadaceae, Cytophagaceae, and Microbacteriaceae, and the genera Flavobacteria, Caulobacter, Burkholderia, Brevundimonas, compared to the bulk soil. In agricultural soils, Geodermatophilaceae, Flavobacteria and Pseudomonas were relatively more abundant in casts, whereas bulk soil harbored greater relative abundances of taxa related to Acidobacteria GP1. The communities of earthworm casts of native prairies were also significantly different than those from agriculture soils. Casts from prairies had higher abundances of Actinobacteria, including Cellulomonas, Cellulomonas, Pseudonocardia, Geodermatophilaceae, and Propionibacteraceae, whereas casts from agricultural habitats were especially enriched in Flavobacteria and Pseudomonas. Fresh casts from Apporectodea trapezoids from agricultural sites were highly enriched in Flavobacteriaceae, Pseudomonadaceae, Nocardioidaceae and Geodermatophilaceae and in OTUs Flavobacterium, Pseudomonas, and Bradyrhizobiaceae. Co-occurrence networks among communities from bulk soil and earthworm casts collected from agricultural fields were strikingly different than those from prairie soils and formed only two modules of co-occurring taxa, compared to 8-9 modules in the prairie soils, indicating a greater complexity of interactions. Networks from agricultural fields tended to have lower ratios of positive to negative edges (interactions) compared to prairie soils, indicating more competition and antagonism. Thus, the specific co-occurring taxa, as well as the aggregate structure of ecological interactions, are largely distinct between Palouse prairie soil communities versus those of earthworm casts in prairie or agricultural settings.