Reducing Erosion and Sediment Loss with Soluble Calcium Soil Amendments.

Soil amendments yielding soluble Ca have been used throughout history.  Slightly soluble compounds, such as agricultural limestone, must react with acid to release soluble Ca into the soil solution; whereas, highly soluble materials such as calcium chloride can have detrimental impacts on plant growth due to salt or toxicity effects.  A moderately soluble material such as calcium sulfate dihydrate (gypsum) can release sufficient Ca to low electrolyte rainwater or snow melt water to decrease dispersion of soil colloids and increase aggregate stability in the short-term.  Improved infiltration helps to decrease runoff volume while decreasing soil erosion and sediment concentration in runoff waters.  Soil solutions containing soluble Ca can also precipitate dissolved reactive phosphorous and reduce its concentration in runoff waters.   Soluble Ca ions from gypsum dissolution move with infiltrating water to lower soil depths where they can be absorbed by plants roots.  Over the long-term, greater Ca concentrations in the soil solution not only enhance soil aggregate stability, but also promote greater root biomass and stabilize organic matter, which further helps to reduce soil erosion.  Many years of study on the beneficial effects of soluble Ca compounds on erosion processes will be summarized in this presentation.