Nitrate-N load reduction measured in a central Iowa restored oxbow

Schilling, Keith E.; Kult, Keegan; Seemon, Anthony; Wilke, Karen; Jones, Christopher S.

doi:10.1016/j.ecoleng.2018.09.018

Cited by 11 publications

(28 citation statements)

References 10 publications

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“…Multipurpose oxbows can process tile drainage delivered from a typical agricultural field of 8 to 32 ha (20–80 acres), which is similar to areas treated by a bioreactor or saturated buffer. The nitrate retention of the central Iowa oxbow (42 ± 6%) (Schilling et al, 2017, 2018b) is comparable to other BMPs designed for reducing nitrate in tile drainage water. Estimated nitrate reductions for other tile drainage BMPs include bioreactors (43 ± 21%), drainage water management (33 ± 32%), wetlands (52%), and saturated buffers (50 ± 13%) (INRS, 2017).…”

Section: Design Features Life Expectancy Performance and Costmentioning

confidence: 70%

“…Nitrate concentrations were highest in tile drainage water (9–17 mg L −1 ) and lowest in downgradient groundwater (0.2 mg L −1 ), and results indicated that the restored oxbow reduced the influx of nitrate by an average of approximately 45% for the 2‐yr study. A second study conducted at the same central Iowa site, but using a continuously reading nitrate sensor, developed a budget for the oxbow to estimate annual and monthly load reductions (Schilling et al, 2018b). Based on a daily mass balance, the oxbow retained 42.3 kg of nitrate, or 0.21 g N m −2 d −1 , and the retention efficiency was 35.4%.…”

Section: Nitrate Export Reductionmentioning

confidence: 99%

“…However, restored oxbows configured to receive inputs from tile drainage receive considerably more nitrate than oxbows fed only by groundwater discharge or from an occasional flood pulse. Nitrate input to an oxbow fed by tile drainage ranged from 100 to 450 kg yr −1 (Schilling et al, 2017, 2018b), whereas an oxbow constructed to receive inputs from groundwater and flooding only intercepted 15 kg of nitrate during a flood pulse (Schilling et al, 2018a). Thus, oxbows fed by tile drainage provide a greater opportunity to reduce the nitrate load from agriculture to downstream river systems.…”

Section: Nitrate Export Reductionmentioning

confidence: 99%

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Multipurpose Oxbows as a Nitrate Export Reduction Practice in the Agricultural Midwest

Schilling

Wilke

Pierce

et al. 2019

Agricultural & Env Letters

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N utrient export from the agricultural US Midwest influences streams and rivers and contributes to the development of hypoxia in the Gulf of Mexico (Turner et al., 2008). Gulf hypoxia is caused by nitrate exported from row crop agricultural fields via the Mississippi River. One path for nitrate export is leaching from soil and transport to streams through groundwater discharge and subsurface tile drainage systems. Watersheds with tile systems are highly susceptible to increased nitrate losses to streams and rivers, and conservation practices are needed mitigate these losses (Jaynes et al., 2001; Schilling et al., 2012; Tomer et al., 2013). Oxbows are natural waterbodies formed when a river cuts off a meander loop as it migrates within its floodplain (Wohlman and Leopold, 1957). While natural oxbows are among the most biologically diverse aquatic systems in the world (Ward, 1998), in agricultural regions, practices such as stream channelization and removal of riparian vegetation, along with increased drainage from tiles and ditches, profoundly changed natural stream hydrology (e.g., Schumm et al., 1984). Oxbows in agricultural areas tend to be isolated from the main channel and rapidly accumulate sediment and organic material from overbank flooding, as they transition to terrestrial habitat (Constantine et al., 2010). Oxbow restoration reverses this process by removing the fill material and restoring hydrologic connection and aquatic habitat (Kenney, 2018). Wetlands are effective in reducing downstream export of nutrients such as nitrate from agricultural lands (Crumpton et al., 2008). Due to their proximity to streams, oxbows, whether naturally occurring or restored, are a type of wetland that is ideally suited to process nitrate-rich water exiting agricultural fields via natural pathways or artificial tile systems. Thus, restoration of former oxbows (Zambory et al., 2019), particularly where they can intercept

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Section: Design Features Life Expectancy Performance and Costmentioning

confidence: 70%

Section: Nitrate Export Reductionmentioning

confidence: 99%

Section: Nitrate Export Reductionmentioning

confidence: 99%

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Multipurpose Oxbows as a Nitrate Export Reduction Practice in the Agricultural Midwest

Schilling

Wilke

Pierce

et al. 2019

Agricultural & Env Letters

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“…Thus, this only leaves us the option of treating tile drain water at the edge of the field or downstream locations. Even though this may limit the opportunities for establishing wetlands around small streams, some opportunities still exist (Schilling et al 2018) and should be explored for remediating stream waters. Considering that a large quantity of water is draining at a faster rate in early spring (period of high N-loads), there is not enough residence time for microbes to denitrify nitrate from tile water in a bioreactor setting (estimated reductions of 13%-43% in N-loads, Christianson et al 2018).…”

Section: Factors Affecting N-loads In Riversmentioning

confidence: 99%

“…To prevent flooding of these towns, levees have been constructed thus preventing land water interaction. Even though this may limit the opportunities for establishing wetlands around small streams, some opportunities still exist (Schilling et al 2018) and should be explored for remediating stream waters. Similarly, prior to settlement of the Upper Midwest, the Mississippi River had greater access to its floodplain.…”

Section: Factors Affecting N-loads In Riversmentioning

confidence: 99%

Precipitation as the Primary Driver of Variability in River Nitrogen Loads in the Midwest United States

Baeumler

Gupta

2019

J American Water Resour Assoc

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Research Impact Statement: Recent increases in river N-loads in the Midwest United States are primarily caused by wet climate. Under current cropping systems, tile-water remediation will be necessary to reduce river N-loads.ABSTRACT: Nitrogen (N) losses from agricultural lands in the Midwest United States are contributing to the expansion of the hypoxic zone in the Gulf of Mexico. This study evaluated the importance of inter-annual variability in precipitation, land cover, and N fertilizer use on NO 3 + NO 2 -N loads in seven United States Midwestern Rivers using the backward stepwise regression analysis. At the annual scale, fluctuations in the current and previous years' precipitations explained much of the variation in streamflow, baseflow, and N-load. Previous years precipitation effects were associated with fillable soil porosity. In some years, higher residual soil N from previous dry years also contributed to an increase in N-load. Area under soybean production (SOY), a surrogate for replacement of prairies and small grains was generally not a significant explanatory variable. Fertilizer use from 1987 to 2012 was also not a significant explanatory variable in the annual analysis. Precipitation in both the current and previous months and previous year were important in explaining variation in monthly streamflow, baseflow, and N-load. SOY was significant in one or two months from June to August, but had a higher pvalue than precipitation. We conclude recent increases in river N-loads are primarily due to wet climate and minimally due to the changes in land cover or N fertilizer use. Under current cropping systems and agronomic N application rates, tile water remediation will be necessary to reduce river N-loads.(

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Applying a Hybrid Modeling Approach to Evaluate Potential Pesticide Effects and Mitigation Effectiveness for an Endangered Fish in Simulated Oxbow Habitats

Schmolke

Bartell

Roy

et al. 2021

Enviro Toxic and Chemistry

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The occurrence of some species listed under the United States' Endangered Species Act in agricultural landscapes suggests that their habitats could potentially be exposed to pesticides. However, the potential effects from such exposures on populations are difficult to estimate. Mechanistic models can provide an avenue to estimating the potential impacts on populations, considering realistic assumptions about the ecology of the species, the ecosystem it is part of, and the potential exposures within the habitat. In the present study, we applied a hybrid model of the Topeka shiner (Notropis topeka), a small endangered cyprinid fish endemic to the US Midwest, to assess the potential population‐level effects of realistic exposures to a fungicide (benzovindiflupyr). The Topeka shiner populations were simulated in the context of the food web found in oxbow habitats that are the focus of ongoing habitat restoration efforts for the species. We applied realistic, time‐variable exposure scenarios and represented lethal and sublethal effects to individual Topeka shiners using toxicokinetic–toxicodynamic models. With fish in general showing the highest sensitivity to the compound, direct effects on simulated Topeka shiner populations governed the population‐level effects. We characterized the population‐level effects of different exposure scenarios with exposure multiplication factors (EMFs) applied. The introduction of a vegetative filter strip (VFS; 15 ft; 4.6 m) between the treated area and the oxbow habitat was shown to be effective as mitigation because EMFs were 2 to 3 times higher than for the exposure scenario without VFS. Environ Toxicol Chem 2021;40:2615–2628. © 2021 SETAC

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Nitrate-N load reduction measured in a central Iowa restored oxbow

Cited by 11 publications

References 10 publications

Multipurpose Oxbows as a Nitrate Export Reduction Practice in the Agricultural Midwest

Multipurpose Oxbows as a Nitrate Export Reduction Practice in the Agricultural Midwest

Precipitation as the Primary Driver of Variability in River Nitrogen Loads in the Midwest United States

Applying a Hybrid Modeling Approach to Evaluate Potential Pesticide Effects and Mitigation Effectiveness for an Endangered Fish in Simulated Oxbow Habitats

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