TY - JOUR
T1 - Long-term nitrate removal in three riparian buffers
T2 - 21 years of data from the Bear Creek watershed in central Iowa, USA
AU - Groh, Tyler A.
AU - Isenhart, Thomas M.
AU - Schultz, Richard C.
N1 - Funding Information:
This continued work was supported by funds from the McIntire-Stennis Cooperative Forestry Program , and from the Leopold Center for Sustainable Agriculture . Funds to support the author who compiled this research were provided by the Agriculture and Food Research Initiative (AFRI), Competitive Grant no. 2013-67019-21384 , from the USDA National Institute of Food and Agriculture.
Publisher Copyright:
© 2020
PY - 2020/10/20
Y1 - 2020/10/20
N2 - Riparian buffers are a conservation practice that increases vegetation diversity on the agricultural landscape while providing environmental benefits. This study specifically focused on the ability of riparian buffers to remove nitrate from shallow groundwater. There are many studies that assessed nitrate removal within buffers, but not many have a long-term, continuous data set that can analyze for variation in nitrate removal rates over time. Here we report on 21 years of nitrate well data, from 1996 through 2017, for three buffers in the Bear Creek watershed in central Iowa. These buffers are named using abbreviations to help keep landowners anonymous (e.g. RN, RS, and ST). Studied buffers RS and ST showed greater nitrate reduction (or removal) after 10 and 6 years of its establishment, respectively. Buffer RN did not experience a significant nitrate removal increase with time, but instead had higher nitrate removal rates when compared to buffers RS and ST of 10.3 g NO3−-N m−1 day−1 from the start of this study. From this data, we suggest that past land management played a major role in the responses observed. RN had previously been established in cool-season grasses for grazing before being converted to a buffer, while RS and ST had been managed in a corn and soybean rotation. RN was thought to have higher denitrification immediately with increased labile soil carbon input and enhanced soil aggregation due to the grassland perennials, while buffer vegetation establishment increased soil carbon inputs and soil aggregation over time for RS and ST. These nitrate removal trends would not have been observed without access to long-term, continuous data. This study highlighted the importance of long-term data sets and the need to assess conservation practices over time to determine their longevity and efficiency with time.
AB - Riparian buffers are a conservation practice that increases vegetation diversity on the agricultural landscape while providing environmental benefits. This study specifically focused on the ability of riparian buffers to remove nitrate from shallow groundwater. There are many studies that assessed nitrate removal within buffers, but not many have a long-term, continuous data set that can analyze for variation in nitrate removal rates over time. Here we report on 21 years of nitrate well data, from 1996 through 2017, for three buffers in the Bear Creek watershed in central Iowa. These buffers are named using abbreviations to help keep landowners anonymous (e.g. RN, RS, and ST). Studied buffers RS and ST showed greater nitrate reduction (or removal) after 10 and 6 years of its establishment, respectively. Buffer RN did not experience a significant nitrate removal increase with time, but instead had higher nitrate removal rates when compared to buffers RS and ST of 10.3 g NO3−-N m−1 day−1 from the start of this study. From this data, we suggest that past land management played a major role in the responses observed. RN had previously been established in cool-season grasses for grazing before being converted to a buffer, while RS and ST had been managed in a corn and soybean rotation. RN was thought to have higher denitrification immediately with increased labile soil carbon input and enhanced soil aggregation due to the grassland perennials, while buffer vegetation establishment increased soil carbon inputs and soil aggregation over time for RS and ST. These nitrate removal trends would not have been observed without access to long-term, continuous data. This study highlighted the importance of long-term data sets and the need to assess conservation practices over time to determine their longevity and efficiency with time.
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U2 - 10.1016/j.scitotenv.2020.140114
DO - 10.1016/j.scitotenv.2020.140114
M3 - Article
C2 - 32563878
AN - SCOPUS:85086499243
VL - 740
JO - Science of the Total Environment
JF - Science of the Total Environment
SN - 0048-9697
M1 - 140114
ER -