R/E-22f

Strategic focus area:

Description:

To ensure that Maryland's coastal resources are resilient and sustainable, the agriculture that is vital to the state economy must find ways to reduce nutrient runoff into precious water resources. One such way is a best management practice (BMP) that uses control structures to manage drainage water levels in farm fields. The goal is to increase the amount of denitrification by elevating the water table. Preliminary studies have shown that this BMP reduces nitrogen leaching by half because it increases denitrification, which microbially reduces nitrate to inert nitrogen gas (N₂). The concern is that nitrous oxide (N₂O), a greenhouse gas (GHG) about 300 times more potent than carbon dioxide (CO₂), is also a product of denitrification. Quantifying the potential trade-off between nitrate runoff reduction and N₂O emissions is essential to evaluating the effectiveness of the drainage water management strategy, before it is promoted as a sustainable solution. To accurately measure the amount of N₂O emitted and denitrification occurring in agricultural soils, two innovative methods will be applied in the study. The first is to use traditional manual soil gas emission chambers with a Picarro instrument to measure soil flux data in real-time. This recent in-situ, fast response, highly sensitive technique reduces the time and labor it takes to measure soil fluxes in the field, thereby increasing sampling sites and sampling rates to more accurately characterize a heterogeneous agriculture field. The second method in this study is a natural abundance isotope technique that measures ¹⁵N , ¹⁷O, and ¹⁸O of nitrate using the denitrifier method, combined with a nitrogen mass balance, to yield a mechanism for estimating denitrification. These methods will produce more accurate estimations of N₂O emissions and dentirification on the field scale. Sampling for both methods will take place over the entire year but with particular emphasis during the active growing season, when most fertilizer and irrigation is applied, and nitrogen rich runoff is more of a concern. Sampling emphasis during these times are when agricultural management such as irrigation, fertilization, and drainage water level change occur in the field. With collaboration and input from a Caroline County Extension Agent, Jim Lewis, the goal of the project is tailor the research towards the needs of farmers that apply these BMPs and provide a workshop demonstrating their use. As an extension agent, Jim has access and knowledge of what farmers are willing to implement on their land. In addition, collaboration with the Coastal SEES project, administered by Dr. Tom Fisher, will be a great pathway for outreach to the community, undergraduate, and K-12 education. One aim of the SEES project is to provide insight into the implementation of BMPs, aligning closely with the goals of the proposed research.