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Title: Groundwater nitrate following installation of a vegetated riparian buffer

item Logsdon, Sally
item Tomer, Mark
item Burkart, Michael

Submitted to: Science of the Total Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/19/2007
Publication Date: 10/15/2007
Citation: Yamada, T., Logsdon, S.D., Tomer, M.D., Burkart, M.R. 2007. Groundwater nitrate following installation of a vegetated riparian buffer. Science of the Total Environment. 385(1-3):297-309.

Interpretive Summary: Crop nutrients, such as nitrate in agricultural soils, can be leached to groundwater and lost to an adjacent stream. This study showed that trees and grasses planted along the stream as a buffer significantly reduced nitrate in the groundwater beneath the vegetative buffer, in three to five years after planting. Denitrification was not indicated in the groundwater, and nitrate loss was determined to be from plant uptake. This study is important for land managers and policy-makers to show the usefulness of buffer vegetation along a stream. This study is also important for scientists who want to understand the mechanisms of buffer vegetation in reducing chemicals lost to adjacent streams.

Technical Abstract: Buffers are often planted along streams to reduce nutrient loss from fields. The purpose of this study was to determine if a vegetated buffer could significantly decrease groundwater nitrate-nitrogen (NO3) concentrations. During 2000 and 2001, a three-part buffer was planted adjacent to a first-order stream in the deep loess region of western Iowa. Poplar and walnut trees occupied the stream-edge strip next to a strip of alfalfa and brome grass with a strip of switch grass adjacent to the crop edge. Non-parametric statistics showed significant declines in NO3 concentrations in shallow groundwater following buffer establishment, especially mid-2003 and later. The dissolved oxygen (DO) generally was >5 ppm beneath the buffer suggesting that loss of NO3 is a result of plant uptake, rather than denitrification. Results of such short-term changes in groundwater NO3 provide evidence that vegetated riparian buffers may yield water-quality benefits in less time than has previously been hypothesized.