Location: Water Quality and Ecology ResearchTitle: Irrigation potential of suspended solids and nutrients from tailwater recovery systems Author
Submitted to: Water Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/2/2017
Publication Date: N/A
Citation: N/A Interpretive Summary: Conservation practices such as tailwater recovery systems are being utilized as additional irrigation sources in areas suffering from groundwater depletion. However, little is known about the day-to-day water quality of these practices. A two-year study was conducted where water samples were collected weekly (during the growing season) and every three weeks (non-growing season) to determine potential loads of nutrients being "reapplied" to farm fields through a tailwater recovery system. Results showed that although nutrient loads can be recycled through the agricultural system, the amount is not sufficient enough to cause farmers to reduce their fertilizer applications to the fields. This study is important because it provides evidence that nutrients recycled through tailwater recovery systems are not in significant amounts to allow farmers to decrease their normal nutrient applications.
Technical Abstract: Within the Lower Mississippi Alluvial Valley (Mississippi Delta), best management practices (BMP) are being utilized to mitigate nutrient loading from agricultural landscapes to downstream waters. This study was conducted to determine the potential to use solids, P and N captured by tailwater recovery (TWR) systems for reuse onto production fields through irrigation applications. Six TWR systems located in the Mississippi Delta were assessed for seasonal changes in water nutrient concentrations and total nutrient loads. Samples were collected every three weeks from 2013 to 2015 for seasonal analyses and weekly during 2014 and 2015 growing seasons for nutrient load analyses. Spring water samples had greater concentrations of solids than in winter and summer, as well as P than in summer. In addition, spring had greater concentrations of nitrate-nitrite than in all seasons, and ammonium than in summer and fall. Organic N concentrations in water samples collected from TWR systems were greater in the fall than in the winter or spring. Mean nutrient loads per hectare recycled onto the landscape were 0.30 kg ha-1 solids, 0.20 kg ha-1 P, and 0.86 kg ha-1 N, with the N being irrigated as 77% organic. The greatest concentrations in TWR system solids and nutrients occurred during the spring instead of the summer irrigation season, thereby reducing the potential solids and nutrients to be irrigated. Tailwater recovery systems can be used to recycle solids, P and N onto the agricultural landscapes through irrigation events; however, nutrient loads will not be sufficient to alter agronomic fertilizer recommendations.