The missing carbon link: Are ag lime and groundwater irrigation sequestering carbon?

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Farmers routinely add inorganic carbon to row crop soils in the form of crushed lime (e.g. CaCO₃ or CaMg(CO₃)₂) and/or inadvertently as bicarbonate (HCO₃^-) naturally dissolved in groundwater used for irrigation.  In the soil these carbonates can act as either a source of CO₂ to the atmosphere or a sink for keeping additional CO₂ out of the atmosphere. Yet the relationship between nitrogen fertilizer amount, irrigation, and carbonate fate is not well understood.  We are collecting soil porewater from 1.2-3.3 m depths at the Kellogg Biological Station LTER Resource Gradient Experiment and analyzing their chemistry to trace the fate of inorganic carbon and other ions across a nitrogen fertilizer gradient, with and without groundwater irrigation.  This poster will show porewater chemistry results from 2014 to present.