Craig Sheaffer
Department of Agronomy and Plant Genetics
University of Minnesota


  • Seed of common Midwestern agricultural weeds was buried in 47 fields on 15 certified organic farms in Minnesota.
  • Long-term cropping history was collected from organic certification records.
  • Weed seed was excavated following a year of burial and tested for viability. Surrounding soil was sampled and analyzed for physicochemical composition, and bacterial and fungal DNA was extracted and sequenced.
  • Higher sand content in soil, and greater frequency of winters under living vegetative cover, were associated with greater bacterial community diversity. However, increased bacterial diversity was not associated with higher rates of weed seed death.
  • Weed seed death was not associated with management history or bacterial family abundances, but did vary with soil composition. Specifically, higher silt content was correlated with increased death of Setaria viridis and Chenopodium album seed.
  • In a controlled plot experiment, one year of cover crop planting did not produce detectable differences in soil bacterial communities.

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