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Phosphorus mitigation during springtime runoff by amendments applied to grassed soil
J Uusi-Kämppä1, E Turtola, A Närvänen
1MTT Agrifood Research, Finland. jaana.uusi-kamppa@mtt.fi
Journal of Environmental Quality
|February 29, 2012
Summary
Freezing and thawing grassed soils increases phosphorus runoff. Iron-based soil amendments significantly reduced dissolved reactive phosphorus (DRP) and total phosphorus (TP) concentrations in surface runoff, offering a solution for buffer zones.
Area of Science:
- Environmental Science
- Soil Science
- Agricultural Science
Background:
- Permanent grass vegetation on slopes helps prevent soil erosion.
- Decaying grass can release significant dissolved reactive phosphorus (DRP) into springtime runoff.
- Understanding phosphorus dynamics in grassed buffer zones is crucial for water quality management.
Purpose of the Study:
- To investigate the impact of freezing and thawing on phosphorus concentrations in surface runoff from grassed soils.
- To evaluate the effectiveness of calcium (Ca) and iron (Fe) based soil amendments in reducing phosphorus runoff.
- To assess the potential of P-binding materials for improving DRP retention in buffer zones.
Main Methods:
- Indoor rainfall simulations were conducted on grass-vegetated soil blocks from Finland.
- Soil samples were amended with gypsum, chalk powder, Fe-gypsum, or granulated ferric sulfate, alongside untreated controls.
- Surface runoff was analyzed for DRP, total dissolved P (TDP), total P (TP), and suspended solids after freezing and thawing cycles.
Main Results:
- Freezing and thawing significantly increased DRP concentrations in control soil runoff (0.19 to 0.46 mg L, peaking at 2.6-3.7 mg L).
- Fe-amended soils showed 57-80% lower DRP and 47-72% lower TP concentrations compared to controls.
- Ca-based amendments (gypsum, chalk powder) did not significantly alter phosphorus concentrations in runoff.
Conclusions:
- Iron-containing amendments are effective in reducing phosphorus runoff from grassed soils, particularly after freeze-thaw events.
- Fe amendments show promise for enhancing DRP retention in buffer zones and mitigating phosphorus loss to waterways.
- Ca-based amendments were ineffective in reducing phosphorus runoff in this study.
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