Contrasting Nutrient Mitigation and Denitrification Potential of Agricultural Drainage Environments with Different Emergent Aquatic Macrophytes. Issue 4 (1st July 2015)

• Record Type: Journal Article
• Authors: Taylor, Jason M.; Moore, Matthew T.; Scott, J. Thad
• Is Part Of: Journal of Environmental Quality. Volume 44:Issue 4(2015)
• Page Start: 1304
• Page End: 1314
• Publication Date: 2015-07-01
• Subjects: Agricultural ecology -- Periodicals; Environmental engineering -- Periodicals; Pollution -- Periodicals; 630
• DOI: 10.2134/jeq2014.10.0448
• Languages: English
• ISSNs: 0047-2425

Abstract

Abstract : Remediation of excess nitrogen (N) in agricultural runoff can be enhanced by establishing wetland vegetation, but the role of denitrification in N removal is not well understood in drainage ditches. We quantified differences in N retention during experimental runoff events followed by stagnant periods in mesocosms planted in three different vegetation treatments: unvegetated, cutgrass [ Leersia oryzoides (L.) Sw.], and common cattail ( Typha latifolia L.). We also quantified denitrification rates using membrane inlet mass spectrometry from intact cores extracted from each mesocosm treatment. All treatments retained 60% or more of NO3 − –N loads during the 6‐h experimental runoff event, but mesocosms planted with cutgrass had significantly higher (68%) retention than the cattail (60%) or unvegetated (61%) treatments. After the runoff event, mesocosms planted in cattail reduced NO3 − –N concentrations by >95% within 24 h and cutgrass achieved similar reductions within 48 h, whereas reductions in the unvegetated mesocosms were significantly less (65%). Cores from cutgrass mesocosms had significantly higher average denitrification rates (5.93 mg m −2 h −1 ), accounting for as much as 56% of the immobilized NO3 − –N within 48 h, whereas denitrification rates were minimal in cores from the unvegetated (−0.19 mg m −2 h −1 ) and cattail (0.2 mg m −2 h −1 ) mesocosms. Our findings have implications for mitigating excess NO3 − –N in agricultural runoff. While vegetated treatments removed excess NO3 − –N from the water column at similar and significantly higher rates than unvegetated treatments, the high denitrification rates observed for cutgrass highlight the potential for permanent removal of excess N from agricultural runoff in vegetated ditches and wetlands.