QUANTIFYING NET NUTRIENT MITIGATION POTENTIAL OF ESTABLISHING RICE CUTGRASS IN AGRICULTURAL DITCHES: NUTRIENT UPTAKE VERSUS RELEASE
Emergent wetland plants vary in their capacity to regulate nutrient levels in shallow aquatic environments and can play a significant role in mitigating nutrient runoff from agricultural fields. Fully understanding the role of plant species in nutrient mitigation requires quantifying seasonal patterns of nutrient uptake and release over annual cycles of growth and senescence. We studied nitrogen (N) and phosphorus (P) uptake and release in simulated wetland ecosystems planted with rice cutgrass [Leersia oryzoides (L.) Sw.]. We conducted simulated runoff events that enriched mesocosms with high DIN across a gradient of increasing P enrichment to quantify uptake rates during the summer growing season. We also measured cutgrass breakdown and nutrient release from mesocosms across 14 storm events after senescence. Results show that P loss during winter storm events was not significantly different among mesocosms representing the P enrichment gradient, indicating that excess P was not lost through plant senescence. Similarly, N loss during storms represented less than 10% of N removal during the summer. Rice cutgrass appears to be a viable candidate for enhancing management of ditches and wetlands to mitigate impacts of nutrient runoff on downstream aquatic ecosystems.
Sam Testa (Primary Presenter/Author), USDA, Agricultural Research Service, National Sedimentation Lab , email@example.com;
Jason M. Taylor (Co-Presenter/Co-Author), USDA, Agricultural Research Service, National Sedimentation Lab, firstname.lastname@example.org;
Matt Moore (Co-Presenter/Co-Author), USDA, Agricultural Research Service, National Sedimentation Lab, email@example.com;