How Salinity Influences Soil Organisms: Earthworms, Archaea, Bacteria and Fungi

Abstract

Soil salinity is a naturally-occurring issue in the Great Plains. Current standards for saline soil designation are based on plant tolerance levels. This thesis expands salinity knowledge into salinity responses of other soil organisms. I used laboratory mesocosms to examine survival and fecundity or cocoon production of earthworms in the Apporectodea complex to increasing levels of salinity, with or without supplemental organic matter (OM). I then used a split-bin design to examine earthworm choice between combinations of saline and non-saline soils, with and without supplemental OM. I found that earthworms avoided saline soils, but survival and production was steady across salinity levels and in some cases decreased with added OM. I then quantified abundance and diversity of microbial groups in field-collected saline and non-saline soils in increments to 120 cm depth. The response of microbes to depth were stronger than their responses to salinity. Both important groups of soil organisms appear tolerant to salinity levels.