Oral Presentation Freshwater Sciences 2023

Insights on nitrate and orthophosphate transport in agricultural catchments during high-intensity rainfall events (#219)

Gurpal S Toor 1 , Charles Burgis 1 , Bradley Kennedy 1 , Shuiwang Duan 1 , Fajun Sun 1 , Emileigh Lucas 1 , Patricia Steinhilber 1
  1. University of Maryland, College Park, MARYLAND, United States

Agricultural catchments under row crop production (maize-soybean crop rotation) are hot spots of nitrate (NO3) and orthophosphate (PO4) losses to waterways. We investigated the transport of NO3 and PO4 in ~15 agricultural catchments in the mid-Atlantic United States. The drainage area under these catchments ranged from 6 to 140 acres, with a 1 to 13% slope, and mean sea level at outlets from 1 to 179 m. All catchments were instrumented with ISCO samplers, flow meters, and rain gauges and drained via overland flow, tile drainage, and open ditches. The sample collection pacing across catchments ranged from 0.03 to 3.89 mm in individual stormwater events. This presentation will discuss (i) how catchment characteristics and field management controlled the transport of NO3 and PO4, (ii) how the use of insitu sensors provided additional insights into mechanistic processes driving nutrient flux at minute intervals, and (iii) what strategies are needed to mitigate losses of NO3 and PO4 from agricultural catchments with abundant nutrient inputs.