Search results

beaver dam
Practice: 
Edge-of-Field

Title: Dam! Impacts of Beaver Dams on Surface and Groundwater Quality

Location: 

Time Period: 2020 - Present

Research Team: Billy Beck, Thomas Isenhart, Keith Schilling, Peter Moore, Richard Schultz, and Tyler Groh

Project Description: Beaver (Castor canadensis) activity (i.e., damming of streamflow) holds significant potential to impact in-stream nutrient processing, through reduction of streamflow velocity and increase of water residence time within pools, trapping of sediment and organic material, raising of riparian groundwater tables and restoration of channel-floodplain connectivity. Thus, dams may represent a “no-cost in-stream conservation practice” that provides compound benefits beyond water quality and quantity, such as enhanced wildlife habitat and increased riparian vegetation diversity. Few studies have focused exclusively on beaver dam impacts to in-stream nutrient processing and watershed-scale nutrient loading, especially in the agricultural Midwest, where watersheds frequently exhibit elevated nutrient loads, flashy hydrology and stream channel incision.

The overall goals of this project are to identify and quantify key nutrient-removal processes associated with beaver dams and estimate the potential impact of dams on watershed-scale nutrient loading within the agricultural Midwest. To achieve project goals, we will pursue three main objectives: 1) quantify hydrologic impacts of beaver dams at the stream reach-scale in select Iowa watersheds; 2) quantify in-stream and shallow groundwater nutrient processing impacts of beaver dams at the stream reach-scale in select Iowa watersheds; and 3) expand stream reach-scale results to estimate watershed-scale hydrologic and nutrient loading impacts of beaver dams.

Publications:

Funders: Iowa Nutrient Research Center

Disclaimer: This is an active research site, please contact Billy Beck (wjbeck@iastate.edu) prior to planning any site visits.

perennial groundcover between corn rows
Practice: 
Land Management

Title: Field Trials to Evaluate N Export from Perennial Groundcover Corn Systems

Location: Northeast Iowa Research and Demonstration Farm, Iowa State University

Time Period: 2020 - Present

Research Team: D. Raj Raman, Kenneth J. Moore, and Daniel A. Andersen

Project Description: Corn and soybean dominate the Midwestern landscape. Both are annuals, only present on the landscape for a fraction of the year. In their absence, they cannot intercept and protect soil from rainfall, nor can they slow runoff and promote infiltration. Members of the research team pioneered a perennial groundcover (PGC) system for corn, wherein a summer-dormant perennial groundcover, such as fescue, provides year-round soil cover. Managed correctly, the corn thrives because the cover is dormant in the summer. The PGC approach requires fewer late and early-season field activities, which are barriers to wider adoption of annual cover crops. Modeling predicts that PGC-corn can reduce runoff, enhance soil organic matter and reduce nitrogen leaching. However, further field research is needed to validate modeling to better understand the impact of a PGC-corn system on nitrogen loss. This project will provide experimental data that can be used to validate models and to estimate the potential impacts on nitrogen-export of widespread PGC-adoption. 

Publications:

Funders: Iowa Nutrient Research Center, complimentary funding from the Iowa Pork Producers Association started 9/1/21.

Disclaimer: This is an active research site; please contact D. Raj Raman (rajraman@iastate.edu) or Daniel S. Andersen (dsa@iastate.edu) prior to planning any site visits.

Iowa landscape
Practice: 
Multi-Objective

Title: The effectiveness of carbon credit programs at reducing nutrient losses: An assessment of public and private conservation programs and their interactions

Location: Iowa

Time Period: 2021 – July 2023

Research Team: Hongli Feng, Sarah Carlson, Susanne Hickey, Elizabeth Reaves, Lisa Schulte-Moore, and Wendong Zhang

Project Description (300 words max.): There have been intense interests in carbon sequestration and greenhouse gas (GHG) emission reduction in the agricultural sectors recently. Meanwhile, there have been decades of efforts and investment to reduce nutrient loss from agriculture. From a policy standpoint, carbon and nutrient reduction are inseparable for to two reasons: (a) most conservation practices that reduce nutrient loss also sequester carbon; and (b) both government and private incentives can be used to support the same set of conservation practices. By investigating these links, our team of cross-disciplinary researchers and non-governmental organization (NGOs) partners will evaluate how carbon credit programs will affect nutrient loss reduction with a focus on farmers’ decision-making regarding program participation.

Publications:

Funders: Iowa Nutrient Research Center

Iowa landscape
Practice: 
Nutrient Management

Title: Furthering our understanding of the interaction of cereal rye allelochemicals with Pythium species and their impact on corn in the cereal rye-corn production system

Location: Iowa State University Campus

Time Period: 2021 - Present

Research Team: Alison Robertson and Jyotsna Acharya

Project Description: The most prevalent cover crop used in the corn-soybean production system in Iowa is cereal rye (CR). Management of CR in field crop production system continues to evolve, for example, some farmers are growing CR longer (planting corn into standing green rye) to get more biomass and greater ecosystem services. However, there are challenges associated with greater CR biomass production including reduced corn growth and yield. Proposed reasons for this yield decline in corn are seedling disease and allelopathy.

We have consistently demonstrated a CR cover crop serves as a green bridge for soil-borne pathogens of corn that cause seedling diseases and yield reductions, and we hypothesize allelopathy may also play a role. Allelopathy is a complex process in which plants release chemical compounds that affect the growth and physiological processes, e.g. defenses, of other plants. Allelochemicals also affect plant-microbiome interactions. Recently, with funding from INRC, we demonstrated synthetic MBOA, an allelochemical produced by CR, and secondary metabolites from CR plants reduced corn shoot and root growth in vitro and caused more severe seedling disease when Pythium was present.

The infective propagules (inoculum) of Pythium are oospores, sporangia, zoospores. Their germination is stimulated by seed and root exudates. We hypothesize allelochemicals released from decomposing rye residue favor germination and/or activity of Pythium in the corn spermosphere facilitating increased infection of the seedling that results in poor vigor and corn yield reductions in the cereal rye-corn production system by favoring seedling pathogen-corn interactions and by affecting early corn growth and development. In controlled studies, we will determine the effect of rye exudates on the (i) germination of oospores and sporangia, and (ii) movement of zoospores of Pythium species, belonging to Clade B and F, in the presence and absence of corn seedling exudates.

Publications:

Acharya, J., Kaspar, T. and Robertson, A.E. 2021. Effect of 6-Methoxy-2-benzoxazolinone (MBOA) on Pythium species and corn seedling growth and disease. Plant Dis. https://doi.org/10.1094/PDIS-04-20-0824-SC

Funders: Iowa Nutrient Research Center

Stream bank
Practice: 
Multi-Objective

Title: Influence of bank stabilization on floodplain sediment and phosphorus storage

Location: Nishnabotna River, IA

Time Period: 2021 - Present

Research Team: Peter Moore and Tom Isenhart

Project Description: Eroding river banks are frequently stabilized with rock, concrete, or wood when infrastructure or property is threatened. There is also growing interest in using bank stabilization as a way to reduce nutrient loading from bank erosion. However, little is known about the impacts of bank stabilization on the sediment deposition process on opposing point bars and adjacent floodplain, whose dynamics are closely coupled with bank erosion. If arresting bank erosion also reduces sediment and P deposition and storage elsewhere, the nutrient reduction benefits of streambank stabilization may be less than expected. We are comparing the sediment and P concentrations of eroded and deposited sediment in five stabilized and five un-stabilized river bends in the Nishnabotna River watershed to determine whether bank stabilization has any systematic impact on reach-scale sediment and P storage. We are using aerial imagery and LiDAR elevation data to estimate the total volumes of sediment eroded and deposited from each stabilized and un-stabilized bend. We’re also mapping and sampling different sediment types on each point bar and adjacent floodplain to characterize both the sediment eroded and deposited and its P concentration. We’ll compare the results to determine whether sediment and P storage on point bars and adjacent floodplains is reduced in bends with bank stabilization structures.

Publications:

Funders: Iowa Nutrient Research Center

Disclaimer: This is an active research site, please contact Peter Moore (pmoore@iastate.edu) prior to planning any site visits.

Iowa landscape
Practice: 
Nutrient Management

Title: Managing crop residue to reduce optimum nitrogen fertilizer inputs and increase yield

Location: Ames, IA

Time Period: 2021 - Present

Research Team: Michael Castellano, Alexandria Logan, and Sotirios Archontoulis

Project Description:  There is growing evidence that the amount of both corn and soybean residue affect the optimum nitrogen fertilizer rate to the following corn crop (i.e, the Maximum Return to Nitrogen or MRTN). In the rainfed Corn Belt, high levels of residue are hypothesized to lead to higher optimum nitrogen fertilizer rates. However, recommended nitrogen fertilizer rates do not consider the amount of residue from the previous crop. This project will determine the ability for farmers to adjust optimum nitrogen fertilizer rates based on the amount of corn and soybean residue production in the previous year’s crop. A well-established relationship between residue production and optimum nitrogen fertilizer rate would allow farmers to: i) better manage nitrogen fertilizer inputs as they vary from field-to-field and year-to-year as a function of residue production, and ii) manage residue for lower optimum nitrogen rates.

Publications:

Funders: Iowa Nutrient Research Center

Disclaimer: This is an active research site, please contact Michael Castellano (castelmj@iastate.edu) prior to planning any site visits.

stream sensor station
Practice: 
Multi-Objective

Title: Advanced Modeling of Soil Erosion, Sediment Delivery and Nutrient Export from Iowa Watersheds

Location: Walnut Creek Watershed, Jasper County, Iowa

Time Period: 2020 - Present

Research Team: Matthew Streeter, Rick Cruse, Brian Gelder, Chunmei Wang, and Kevin Cole

Project Description: Soil sediment and sediment bound phosphorus export from agriculturally dominated watersheds is a global crisis that has far-reaching, potentially severe environmental and economic impacts. Multiple sources are known to contribute to surficial exports from these watersheds including in-field sheet and rill erosion, ephemeral gully erosion and streambank erosion. However, accurately quantifying suspended sediment and P export from watersheds is difficult.

The Water Erosion Prediction Project (WEPP) may be utilized to help quantify sediment yields from agricultural fields. Sensitivity analysis and validation indicated that WEPP has high runoff and sediment yield accuracy for small watersheds. Still, scaling up WEPP Watershed to a HUC-12 scale may be difficult. The Daily Erosion Project (DEP) may be used to scale up WEPP, but these new outputs must be ground-truthed with field-collected data.

This project will help to identify and quantify the effects of ephemeral gullies on sediment and P loss. Ultimately, this project will work towards delineating sources of sediment and P export, i.e., hill slopes or ephemeral gullies, from Iowa watersheds, using Walnut Creek watershed in Jasper County, Iowa, as a test for soil erosion, sediment, and nutrient export modeling.

Publications:

Funders: Iowa Nutrient Research Center

Disclaimer: This is an active research site, please contact Matthew Streeter (matthew-streeter@uiowa.edu) prior to planning any site visits.

Corncobs as an alternative carbon source for bioreactors.
Practice: 
Edge-of-Field

Title: Continued assessment of corncobs as an alternative carbon source to enhance bioreactor performance for improved water quality

Location: Boone, Iowa

Time Period: 2021 - 2023

Research Team: Michelle Soupir, Ji Yeow Law, Thomas Isenhart, Natasha Hoover, Gary Feyereisen, Morgan Davis

Project Description: Woodchip bioreactors are a cost-efficient practice to remove nitrates (N) from tile drainage, but the limited regional woodchip supply poses challenges for broad-scale bioreactor implementation efforts. Additionally, poor N removals were observed in woodchip bioreactors when the temperature was low, and N export was high in the spring. These challenges motivated researchers to seek alternative bioreactor carbon substrates that are low-cost, locally available, and can provide improved N removals. Among the carbon substrates evaluated in lab studies, corncobs have shown promising N removals rates and costs. This project aims to investigate the long-term performance of corncob-amended woodchip bioreactors under field conditions. The project objectives are to evaluate and compare i) hydraulic efficiencies, ii) N removal rates, and iii) N removal costs in nine replicated pilot-scale bioreactors (PBRs) using three different woodchip-corncob mixture ratios at three hydraulic retention times (HRTs). Three PBRs were filled with woodchips only (WC100); three PBRs were filled with 75% (by vol.) woodchips and 25% corncobs (CC25); and three PBRs were filled with 25% woodchips and 75% corncobs (CC75). The PBRs from each carbon treatment were operated at 2-, 8-, and 16-hr HRTs, respectively. Our early results showed that hydraulic efficiency was highest in WC100 (0.92±0.14), followed by CC25 (0.86±0.16) and CC75 (0.58±0.17). CC75 exhibited the highest N removal rates (11.6-21.1 g N m-3 d-1), then followed by CC25 (5.7-9.7 g N m-3 d-1) and WC100 (2.0-8.0 g N m-3 d-1). When compared to WC100, the N removal costs of CC75 and CC25 were up to 8.3 and 2.1 times lower, respectively. Overall, the early data suggested that corncob-amended woodchip bioreactors had better nitrate removal rates and cost-efficiencies but lower hydraulic efficiencies. Nonetheless, continued assessment of these PBRs is essential to understand the long-term performance that could be affected by different carbon substrate degradation rates.

Publications:

Schaefer, A., K. Werning, N.L. Hoover, U. Tschirner, T.B. Moorman, G. Feyereisen, A.C. Howe, M.L. Soupir. 2021. Impact of flow on woodchip properties and subsidence in denitrifying bioreactors. Agrosystems, Geosciences & Environment DOI: http://dx.doi.org/10.1002/agg2.20149

Martin, E.A., M.P. Davis, T.B. Moorman, T.M. Isenhart, M.L. Soupir. 2019.  Impact of hydraulic residence time on nitrate removal in pilot-scale woodchip bioreactors. Journal of Environmental Management. 237:424-432. DOI: 10.1016/j.jenvman.2019.01.025

Davis, M.P., E.A. Martin, T.B. Moorman, T.M. Isenhart, M.L. Soupir. 2019. Nitrous oxide and methane production from denitrifying woodchip bioreactor at three hydraulic residence times. Journal of Environmental Management. 242: 290-297. DOI: 10.1016/j.jenvman.2019.04.055

Funders: Iowa Nutrient Research Center

Disclaimer: This is an active research site, please contact Michelle Soupir (msoupir@iastate.edu) prior to planning any site visits.

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