Nitrate concentration-drainage flow (C-Q) relationship for a drained agricultural field in Eastern North Carolina Plain

Abstract

Artificial agricultural drainage has been recognized as the major source of nutrients, especially nitrogen and phosphorus, which raise nutrient levels in sensitive surface water bodies. Using high frequency measurements, researchers have achieved further understanding of water movement and nutrient transport in watersheds. However, the quantification of nutrient dynamics in agricultural drainage still remains unclear. In a drained agricultural field in North Carolina, we installed water quality sensors and flow measurement devices in drain outlets to monitor and quantify the relationship between solute concentration and drainage flow (C-Q relationship). In addition, we also implemented devices to measure groundwater level, rainfall, groundwater quality, temperature, and so on, so that we can describe the background of each event. We found that most of artificial drainage tends to flush nutrients from the fields, which matches with the previous findings; however, the response of C-Q relationships vary with different factors. Our research could help researchers to better understand water movement and nutrient transport in agricultural fields, and thus develop techniques to reduce nutrient emission to surface water bodies.