1a.Objectives (from AD-416)
Vegetated edge-of-field flow in floodplain ecosystems can reduce runoff related contaminants. This project seeks to better understand and measure the efficiency of contaminant removal by constructed wetlands, vegetated ditches, and other low-cost management practices needed to improve water quality. These biologically-focused experiments will also further define ecosystem impairment from agriculture and measure the positive effects of potential best management practices.
1b.Approach (from AD-416)
Investigators will cooperate on edge-of-field studies in semi-aquatic and aquatic drainage systems to facilitate ARS efforts in improving the quality of runoff water from agriculture. In an effort to better manage water by edge-of-field practices, specific studies will measure standard WQ parameters and state-of-the-art invertebrate toxicity in controlled experiments for current use insecticides and agriculturally-applied nutrients.
Research on the use of vegetated agricultural drainage ditches and controlled drainage (weirs) for mitigation of nitrogen and phosphorus continues at Arkansas State University’s (ASU) Agricultural Research Facility (aka “Ditch Farm”). A series of experiments conducted May 17-18, 2011, examined the nitrogen mitigation differences in ditches with controlled drainage (concrete weirs) and without controlled drainage (no concrete weirs). Weirs designed by Scurlock Industries (Jonesboro, AR) were placed within the ASU ditch systems in early June 2010. For the 2011 experiments, hydraulic residence times were calculated, as was nitrogen removal by the ditch systems. This work will be submitted as a manuscript for journal review. These studies built upon efforts conducted in 2008, 2009, and 2010 on nutrient-drainage ditch mitigation. Studies from 2010 and 2011 included additional scientific investigations into stream metabolism by an ASU graduate student. Likewise, a graduate student from Mississippi State University is analyzing plant root tissue samples for nitrogen reductase activity with the assistance of an ARS post-doctoral research microbiologist from the Water Quality and Ecology Research Unit in Oxford, MS. Results from these activities led to the decision to submit a NIFA proposal (June 3, 2011) for funding to examine impacts on the microbiological communities in ditches responsible for denitrification, where systems routinely undergo massive hydrological shifts from drought to inundation. Monitoring activities included site visits for experiments with ADODR, as well as bimonthly calls to cooperator for progress reports. Quarterly, routine site visits were also conducted by the ADODR.