The Agronomic Receptor Evaluation (phase 2) has considered the ecological direct contact pathway in soil, specifically, the exposure pathway by which terrestrial plants and soil invertebrates may come into direct contact with chemicals in the soil, and applies across all land-use designations. In Alberta, there is variability in whether the direct contact pathway is applicable at intermediate depths for different chemicals of potential concern. At shallower depths, the ecological direct contact pathway guideline must be followed unless another more suitable guideline is available.
This report is phase 2 of 3 of the broader project. The next objective is to assess and validate the findings of Phase 2 in a field setting by assessing the impact of soil salinity, present at depths below 75 cm, on aboveground biomass via restricted root growth. Specifically, this project will investigate scenarios where agricultural plant species are growing in soil with salinity impacts 75 cm below the ground or deeper, to assess if restricted root growth (due to salinity) impacts aboveground growth.
Phase 2 of the project indicated an apparent effect of salinity on alfalfa roots but not on aboveground growth. For this reason, there is a significant benefit in determining whether restricted root depth impacts aboveground growth in a field setting. If aboveground growth is not limited, despite restricted rooting depth, this indicates that agricultural production may be maintained in certain scenarios where contaminated soil is overlain by clean material, depending on the depth of contamination and type of crop present.