Abstract
Extensive network of tile drains present in the Midwest USA accelerate losses of nutrients to receiving ditches, rivers and eventually to the Gulf of Mexico. Nutrient inputs from agricultural watersheds and their role in affecting water quality have received increased attention recently; however, benthic sediment-nutrient interactions in tile-fed drainage ditches is still a matter of active research in consideration to nutrient discharge from tile drains. In this study, phosphorus (P) and nitrogen (N) contents and variability of nutrient retention ability of benthic sediments upstream and downstream from tile drain outlets were evaluated in managed agricultural drainage ditches in Indiana. Sediment samples were collected every three months upstream and downstream from selected tile drains in three ditches in northwest Indiana. Sediment equilibrium P concentrations (EPC0) were measured to examine P adsorption-desorption and equilibrium characteristics of benthic sediments in the ditches. P sorption index (PSI), exchangeable P (ExP), and exchangeable NH4+-N (ExN) were measured to evaluate nutrient retention ability and readily available nutrient content of benthic sediments. Results indicated a dynamic interaction between benthic sediment and overlying water column where sediments were acting as a sink or a source of P. There were no differences in nutrient retention ability between sediments collected upstream and sediments collected downstream from the selected tile drains. While the data, except for ExN, was comparable to reported values by previous studies in Indiana’s drainage ditches, there was no particular seasonal pattern in the content of exchangeable nutrient content in sediments at all three sites. This study also suggested that nutrient uptake by benthic sediments in these drainage ditches is not always efficient; therefore watershed management should focus on minimizing the delivery of nutrients into ditches while maintaining their drainage functionality.
Highlights
Tile-fed drainage ditches are common water management practices in the Midwestern UnitedStates
This study indicates that sediments in drainage ditches could already have high P
The analysis of sediment EPC0 measurements indicated that ditch sediments were acting as a sink or a source of P, or were in equilibrium with water column Total Dissolved P (TDP), without any particular pattern in the ditches
Summary
Tile-fed drainage ditches are common water management practices in the Midwestern UnitedStates. Despite efforts to control the application of fertilizers on at-risk fields of P losses [8], P transport to drainage ditches remain a concern [2,4,9]. The ability of benthic sediments to adsorb P from the water column has been shown to have a strong correlation with particle size [1,15]. Other processes such as hydrology can influence P transport and concentration in drainage ditches [3,16]. Previous studies have reported little retention of P downstream from P input points, including confined animal feeding operations (CAFO’s) and wastewater treatment plants [20,21,22]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
