Submitted to: Proceedings of the Society of Wetland Scientists
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/2011
Publication Date: 7/1/2011
Citation: Kroger, R., Moore, M.T. 2011. Innovative best management practices for improving nutrient reductions in agricultural landscapes. Abstracts of the Joint Meeting of the Society of Wetland Scientists, Wetpol and Wetland Biogeochemistry Symposium, Prague, Czech Republic, 3-8 July, 2011. p. 171. Interpretive Summary: Abstract Only - interpretative summary not required.
Technical Abstract: As the burgeoning human population increases pressures on agriculture for increasing yields, the concomitant strain on the aquatic environment downstream is elevated through non-point source pollution. Traditional management practices of conservation tillage, terracing, and cover crops are good practices but do not create conditions that maximize nutrient reductions. Effective removal of mobile and potentially toxic non-point source pollutants such as nutrients and pesticides requires the enhancement of hydraulic residence time and the creation of biogeochemical conditions conducive for transformation. Conducive conditions include oxidized and reduced conditions for coupled nitrogen nitrification / denitrification, oxidation of pesticides, and enhanced adsorptive capacity for phosphorus sorption. Three innovative management strategies are receiving significant amounts of attention within the Lower Mississippi Alluvial Valley for improving efficiencies within the agricultural landscape for nutrient reductions. These strategies are: slotted pipes as edge of field practice, vegetated drainage ditches that directly receive agricultural runoff, and low-grade weirs in ditches to enhance retention and wetland like conditions. Research has shown that vegetated drainage ditches reduce agricultural runoff concentrations and loads of total inorganic nitrogen and phosphorus by 47 and 53% respectively. Further manipulations of wetland-specific plant uptake within ditch mesocosms have suggested certain plants have greater nutrient assimilatory capacity than others (Ludwigia peploides 82% reduction of NH4+ vs. 37% reduction in Juncus effusus). Low grade weirs have been demonstrated experimentally as well as at the field scale to significantly enhance hydraulic residence time within the drainage ditch system. Similarly, there were statistically higher concentration and load reductions between systems with weirs as compared to systems conventionally drained. Field scale research of low-grade weir impacts on agricultural runoff highlight close to 80% reductions of influent nitrate, ammonia and nitrite concentrations as a result of hypothesized enhancement of the biogeochemical environment within the drainage ditch.