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Surface Water and Groundwater Nitrogen Dynamics in a Well Drained Riparian Forest within a Poorly Drained Agricultural Landscape
Author(s) -
Davis Jennifer H.,
Griffith Stephen M.,
Wigington Parker J.
Publication year - 2011
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2010.0310
Subject(s) - riparian zone , environmental science , hydrology (agriculture) , groundwater , riparian forest , surface water , riparian buffer , buffer strip , soil water , nitrate , drainage , surface runoff , ecology , soil science , geology , environmental engineering , geotechnical engineering , habitat , biology
The effectiveness of riparian zones in mitigating nutrients in ground and surface water depends on the climate, management, and hydrogeomorphology of a site. The purpose of this study was to determine the efficacy of a well drained, mixed‐deciduous riparian forest to buffer a river from N originating from a poorly drained grass seed cropping system. The study site was adjacent to the Calapooia River in the Willamette Valley, Oregon. Water was found to move from the rapid drainage of swale surface water. During winter hydrological events, the riparian forest also received river water. Low nitrate (NO 3 − ) concentrations (0.2–0.4 mg NO 3 − –N L −1 ) in the shallow groundwater of the cropping system were associated with low rates of mineralization and nitrification (33 kg N ha −1 yr −1 ) and high grass seed crop uptake of N (155 kg N ha −1 yr −1 ). The riparian forest soil had higher rates of mineralization (117 kg N ha −1 yr −1 ) that produced quantities of soil N that were within the range of literature values for plant uptake, leading to relatively low concentrations of shallow groundwater NO 3 − (0.6–1.8 mg NO 3 − –N L −1 ). The swale that dissected the cropping system and riparian area was found to have the highest rates of denitrification and to contribute dissolved organic C to the river. Given the dynamic nature of the hydrology of the Calapooia River study site, data suggest that the riparian forest plays a role not only in reducing export of NO 3 − from the cropping system to the river but also in processing nutrients from river water.