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ARS Home » Midwest Area » West Lafayette, Indiana » National Soil Erosion Research Laboratory » Research » Research Project #441760

Research Project: Assessment of Sediment and Chemical Transport Processes for Developing and Improving Agricultural Conservation Practices

Location: National Soil Erosion Research Laboratory

2023 Annual Report

Objective 1: Quantify physical and chemical processes affecting sediment and nutrient transport in surface and subsurface waters. Sub-objective 1.A: Determine the dominant flow pathways for water and nutrient transport in tile-drained headwater watersheds. Sub-objective 1.B: Quantify the effects of landscape, surface, and climate conditions on erosion and related processes. Sub-objective 1.C: Evaluate how flow characteristics impact the ability of soils to behave as nutrient sources and sinks. Objective 2: Evaluate and improve the efficacy of novel soil and water conservation practices. Sub-objective 2.A: Optimize and demonstrate phosphorus removal structures and sorption materials for removing pollutants from water. Sub-objective 2.B: Determine effects of combined management practices on water quality. Objective 3: Enhance soil erosion and water quality models for improved predictions and management of agricultural and forested lands. Sub-objective 3.A: Improve natural resource model functionality and performance. (This is a non-hypothesis research sub-objective.) Sub-objective 3.B: Application of natural resource models and develop modeling techniques. Objective 4: Utilize long-term field and watershed datasets to enhance agricultural production and environmental quality in agroecosystems, and facilitate and support collaborations through the Conservation Effects Assessment Project (CEAP) and Long-Term Agroecosystem Research (LTAR) network. Sub-objective 4.A: Monitor fields and subcatchments in the St. Joseph River Watershed as part of the St. Joseph River CEAP and Eastern Corn Belt LTAR.

Hydrometric monitoring and conservative tracer analysis will be used to evaluate antecedent conditions on surface runoff and subsurface tile drainage flow generation and quantify surface and subsurface flow contributions to water quantity and quality. Runoff and groundwater within a tile-drained watershed will be analyzed to determine soil physical property effects and management practices on water quality. A lab rill channel and soil box will quantify sediment deposition and transport under different hydrologic conditions, and develop equations for process-based erosion models. Surface topographic techniques will be assessed to quantify spatial distribution of soil erosion and sediment deposition, and morphology of the drainage network. Collect high P soils from Western Lake Erie Basin and characterize for chemical and physical properties, followed by flow-through desorption experiments. Construct a subsurface P removal structure on an agricultural tile drain, using Fe-rich P filter media. Monitor inflow and treated water for P removal. Lab studies to assess different biochars at pollutant removal. Lab and field studies will assess conservation practice impacts on water quality at plot and field scales. Continued efforts on physical-based soil erosion model, including improved channel erosion simulation for ephemeral gullies and grass waterways, water quality routines for pollutant losses, and expanded subsurface tile drainage for better winter simulations and controlled drainage management. Changes to science model have resulted in separate code branches. We will unify these to have a single WEPP version applied by user agencies. Incorporate code from graduate student and other research. Conduct simulations using TauDEM, comparing results to both observed data and simulations using TOPAZ. Assess current code bases for WEPP and WEPS, and determine if common algorithms can be shared. Evaluate data needs of WEPP, WEPS, RHEM and RUSLE2 for common databases. Refactor WEPP code and maintain existing functionality. Use web services locally for desktop WEPP and WEPS, and for web-based applications to separate science and database logic from user interfaces. Expand web service software to fully support WEPP. Develop parallel processing for watershed applications, controlled by software service layer. Use parallelization on CPU and GPU processors. Update P-TRAP software, build mobile research/demo P removal structure, and help with P removal structures across the country. Climate change is resulting in elevated temperatures, more variable rainfall occurrence, and more intense rainfall events. Current conservation practices may be less effective in the future, and other practices may be needed to keep soil and pollutant losses to lower desired levels. Modeling studies will be used to assess impacts of climate change on erosion and off-site water quality, and effectiveness of control practices. Collaborate and support ongoing and future CEAP and LTAR projects and initiatives through sharing historical data from fields and watersheds, continued monitoring of field and watershed sites, and collection of new data and samples for cross-location analyses.

Progress Report
Substantial progress related to the project’s Objective 1, “Quantify physical and chemical processes affecting sediment and nutrient transport in surface and subsurface waters” has been made in FY23. In an agricultural headwater watershed located within the St. Joseph River basin, 11 groundwater wells have been installed, positioned based on topography, drainage (tile-drained vs. non-drained), and field management (crop rotation, nutrient management practices). Nine passive runoff samplers were also installed in the watershed, that collect runoff during storm events at locations in the field corresponding to different management practices. At each well and sampler location (n=20 total), water depth, water temperature, and electrical conductivity are monitored every 10 minutes. Water samples collected weekly are analyzed for nutrient concentrations [nitrate nitrogen (NO3-N), ammonium nitrogen (NH4-N), Total Nitrogen (TN), dissolved reactive phosphorus (DRP), Total Phosphorus (TP)], solute tracers - chlorine (Cl), and stable water isotopes. We have also collected historical and current management information including crop type, tillage, nutrient rate, source, timing, and placement data. Soil samples were collected during well installation (0-5, 5-15, 15-30, and 30-60 cm depths) and will be collected in subsequent years to monitor changes in soil nutrient status. Data from the watershed described above and another headwater watershed in the St. Joseph River basin, are being used in conjunction with field and watershed data across the U.S. Midwest as part of the SWIFT (Stable Water Isotope Flowpath Tracing) Project being led by ARS researchers in West Lafayette, Indiana. We have identified six sites across Long-Term Agro-Ecosystem Research (LTAR) network locations in Iowa, Minnesota, and Ohio and one partner location in Ontario, Canada, to collect data on water sources and flow pathways. Each site has initiated sample collection and is sending subsamples of water for analysis of stable water isotopes. This project will continue for up to 2 years depending on climate and/or hydrologic conditions during monitoring. Data from rainfall simulation studies are currently being organized and summarized. A total of 12 rainfall simulations were completed under a range of rainfall intensity and soil moisture conditions. Data will be used to better understand the effects of climate and management practices on water and nutrient transport through the soil profile to tile drains. Approximately 30 high phosphorus (P) soils were collected from within the Western Lake Erie Basin, and another six soils were obtained from various locations around the United States as part of the Conservation Effects Assessment Project (CEAP). Soils were characterized for a variety of properties such as texture, total carbon (C), nitrogen (N), and P, amorphous iron (Fe) and aluminum (Al), pH, electrical conductivity (EC), and various forms of extractable P (resin-P, anion strip P, Mehlich-3 P, water soluble P, etc.). This set of benchmark soils will not only be valuable for the kinetics/flow-through research described in this National Program 211 project plan, but can be used for other experiments in the future. Objective 2, “Evaluate and improve the efficacy of novel soil and water conservation practices” work also progressed in the past year. A tank-style P removal structure was installed near Waterloo, Indiana, designed to flow from the bottom-upward and filled with nine tons of a gravel-metal shavings mixture. Monitoring equipment was installed for automated sampling and flow rate measurements, and all tile drainage is currently being monitored. The buried tank has access from the surface for changing media when necessary and for demonstration-field events. Hundreds of PowerPoint presentation slides regarding P removal structure theory, design, and practical field construction advice were completed, and will be used by NRCS in creating training modules for certification in design and construction of P removal structures. Also, construction of a mobile demonstration P removal structure has been completed, thanks partly to funds from the USDA Innovation Fund. P sorption media needs to be added to the tanks, to be placed on the flatbed trailer. The laboratory portion of the unit has already been completed. Progress has been made in biochar research. Biochars produced at 500 degrees C and 600 degrees C, from spent railroad ties, were extracted for residual creosote compounds. This summer, the extracts will be analyzed for harmful polycyclic aromatic hydrocarbons (PAHs), of which 16 of these compounds are listed as U.S. Environmental Protection Agency (EPA) Priority Pollutants. In addition, the sorption capacity of these biochars for pollutants, including a pesticide (atrazine), trace metal (cadmium), and plant nutrient (P), will be determined. Soil, plant, and grain samples from both Indiana experimental stations (Throckmorton-Purdue Agricultural Center (TPAC), West Lafayette, and Davis Purdue Agricultural Center (DPAC), Farmland) have been collected and are awaiting digestion and analysis. The treatments in these experiments are tillage + cover crops (TPAC) and gypsum + cover crops (DPAC). Lysimeters were not installed due to their poor soil water extract efficiency and their labor-intensive installation. Related to Objective 3, ”Enhance soil erosion and water quality models for improved predictions and management of agricultural and forested lands”, efforts continue with improvements to and modifications of the Water Erosion Prediction Project (WEPP) science model and user interfaces. A web service has been developed that runs the WEPP watershed model. Database templates for simulation channel parameters and impoundment parameters have also been developed. The online GIS user interface is currently being tested to access WEPP simulations and for ease-of-use. Channel and impoundment parameter sets that meet NRCS requirements still need to be configured and tested. During the past year optimizations have allowed multiple watershed simulations to be run over an area of interest, and allow for detailed spatial soil loss estimates to be presented as GIS maps. The WEPP FORTRAN (FORmula TRANslation programming language) code base, originally developed between 1985 and 1995, is being refactored to follow more modern FORTRAN language constructs. This includes more modular code by migrating ‘parameter’ and ‘common block’ source files into a global environment. In addition, WEPP water quality routines are being merged into this system. This work should provide for easier code maintenance along with added functionality. WEPP-Water Quality (WEPP-WQ) model code for multiple overland flow element (OFE) hillslopes and watershed applications has been completed, as well as initial validation studies. A journal article on WEPP-WQ has been published, and a companion article on validation results is in review. More testing is continuing, with plans for an updated public release later in 2023. An NSERL scientist organized an international conference on soil erosion research, and USDA-ARS was a co-sponsor. The American Society of Agricultural and Biological Engineers (ASABE) Soil Erosion Research Under a Changing Climate international symposium was successfully held in Aguadilla, Puerto Rico, USA on January 8-13, 2023, with over 130 participants including ARS, NRCS, Forest Service, and university scientists and students. A symposium proceedings USB drive, a printed Abstract Book, and online Proceedings at the ASABE Technical Library website were published. In addition to oral and poster sessions, the symposium also included a panel of mostly ARS scientists discussing future erosion research needs. This conference and related presentations and discussions are helping to guide plans for erosion research by ARS, NRCS, FS, and other collaborators into the future. Substantial progress related to Objective 4, “Utilize long-term field and watershed datasets to enhance agricultural production and environmental quality in agroecosystems, and facilitate and support collaborations through the CEAP and LTAR network” has been made. Scripts were developed in Python to query the Aquarius data streams and extract data to Excel files. This includes querying which data parameters are available and pulling other information from web services. Work has started to allow this data to be used in other databases, with some imported to the time series database InfluxDB which allows efficient access for large datasets. The user interface software Grafana has been paired with the backend InfluxDB database to graph large amounts of data in a web-based interface. Ongoing work to allow the scripts to be customizable for data ranges and linked to a custom user interface to download the data continues. In addition to the SWIFT project, the NSERL is leading and contributing to multiple CEAP and LTAR cross-location projects. We have collected samples or shared data for the projects summarized below: CEAP National Legacy P project; Old vs. New P separation; contribution: Field hydrology, water quality, and management practice data CEAP National Legacy P project; APLE modeling; contribution: Field hydrology, water quality, and management practice data CEAP National Legacy P project: Soil Sampling Campaign; contribution: n=100 soil samples LTAR Drainage Working Group: Microplastics; contribution: Biweekly sampling of tile water from two field sites, hydrology data LTAR Drainage Working Group; Edge-of-field practice effectiveness; contribution: Field hydrology, water temperature data from two field sites LTAR Water Quality Working Group; Algal eutrophication thresholds; contribution: Monthly sampling of ditch water from one watershed site, hydrology and water quality data

1. Water Erosion Prediction Project (WEPP) Water Quality (WQ) Model completed and validated. New functionality and capabilities have been added to the USDA WEPP model, allowing prediction of transport and losses of agricultural nutrients and chemicals, that takes full advantage of WEPP’s detailed field estimation of infiltration, runoff, and sediment loss estimations. ARS researchers and scientists at Purdue University in West Lafayette, Indiana, completed development of the WEPP-Water Quality (WEPP-WQ) model and it is available in the Github repository ( The water quality routines utilized were based upon those in the USDA-ARS Soil and Water Assessment Tool (SWAT) model, with some necessary modifications and enhancements. Validation was conducted using field rainfall simulator data from studies in Indiana and Nebraska, with satisfactory predictions of nitrogen (N) and phosphorus (P) losses in runoff, greatly improved with calibration. The WEPP-WQ model can be applied to single (one soil and one crop/management) and multiple (multiple soils and/or crop/management) strips down a hillslope, as well as to small field-scale watersheds with multiple hillslope profiles, channels, and impoundments. It provides additional functionality to users of the WEPP model, to assess the impacts of conservation practices on nutrient and pesticide losses. Improved ability to determine N and P losses from fields under current and alternative management systems may ultimately assist conservation agencies in developing plans to reduce off-site water quality issues, such as harmful algal blooms.

2. The uncertainty of phosphorus budgets on cropland is often too large to assess phosphorus management. Phosphorus (P) is a critical nutrient for crop growth, but once lost from agricultural fields it can result in eutrophication and harmful algal blooms in downstream water bodies. Improving P use efficiency and developing conservation practices to mitigate environmental impacts of agricultural P inputs are therefore critical for the sustainable intensification of agriculture. Led by ARS researchers in West Lafayette, Indiana, a group of 47 scientists from 15 Long-Term Agro-Ecosystem Research (LTAR) network locations and nine partner organizations in the United States and Canada synthesized data on P inputs (fertilizer/manure application rate, irrigation water, and atmospheric deposition) and outputs (crop removal, surface runoff, and leachate) from agricultural systems. The publicly-available dataset produced from this work, the P-FLUX database, includes P budgets and budget uncertainty calculations for 61 diverse cropping systems across long-term research sites in 22 U.S. states and two Canadian provinces. Research results showed that in many cases (39%), the uncertainties in manure or fertilizer applications and crop removal were too large to determine whether P was increasing, decreasing, or not changing. Recommendations were developed to decrease these uncertainties, including measuring the application rate and the P concentration of manures and measuring both crop yields and the P contents of the harvested materials. Measuring other P fluxes may be important to assess the full impacts of management practices, while measuring the P contained in soil is useful to validate the P budget. The data and recommendations developed through this work can be implemented to facilitate improved quantification of P cycling/loss and be used to address complex local-, regional-, and national-scale P management challenges.

3. Nationwide phosphorus budget quantification. Quantified the magnitude and uncertainty of phosphorus budgets across diverse North American cropping systems. Phosphorus is a critical nutrient for crop growth, but once lost from agricultural fields it can result in eutrophication and harmful algal blooms in downstream water bodies. Led by ARS researchers in West Lafayette, Indiana, data on phosphorus inputs (fertilizer/manure application rate, irrigation water, atmospheric deposition) and outputs (crop removal, surface runoff, leachate) from 61 diverse cropping systems across long-term research sites in 22 U.S. states and two Canadian provinces were synthesized to calculate phosphorus budgets. Through this research, gaps in knowledge were identified and recommendations were developed for measuring phosphorus fluxes and calculating phosphorus budgets. Research findings provide guidance for improving phosphorus use efficiency and developing conservation practices to mitigate environmental impacts of agricultural systems.

Review Publications
Mcgehee, R.P., Flanagan, D.C., Engel, B.A. 2023. A WEPP-Water Quality model for simulating nonpoint source pollutants in nonuniform agricultural hillslopes: Model development and sensitivity. International Soil and Water Conservation Research. 11:3(455-469).
Lee, S., Chu, M.L., Guzman, J.A., Flanagan, D.C., Moriasi, D.N., Fortuna, A., Starks, P.J. 2022. Integrated modeling for simulating sediment production and transport in agricultural landscapes. Environmental Modelling & Software. 160. Article 105605.
Williams, M.R., Livingston, S.J., Duriancik, L.F., Flanagan, D.C., Frankenberger, J.R., Gillespie, R.B., Gonzalez, J.M., Huang, C., Penn, C.J., Smith, D.R., Renschler, C.S. 2023. Twenty years of conservation effects assessment in the St. Joseph River watershed, Indiana. Journal of Soil and Water Conservation. 78(1):12A-19A.
Penn, C.J., Camberato, J., Wiethorn, M. 2022. How much phosphorus uptake is required for achieving maximum maize grain yield? Part 1: Luxury consumption and implications for yield. Agronomy Journal. 13(1).Article:95.
Penn, C.J., Camberato, J., Wiethorn, M. 2023. How much phosphorus uptake is required for achieving maximum maize grain yield? Part 2: Impact of phosphorus uptake on grain quality and partitioning of nutrients. Agronomy Journal. 13(1). Article: 258.
Elliot, W.J., Flanagan, D.C. 2023. Estimating WEPP cropland erodibility values from soil properties. Journal of the ASABE. 66(2):329-351.
Feyereisen, G.W., Ghane, E., Schumacher, T.W., Dalzell, B.J., Williams, M.R. 2023. Can woodchip bioreactors be used at a catchment scale? Nitrate performance and sediment considerations. Journal of the ASABE. 66(2):367-379.
Guo, T., Liu, Y., Shao, G., Engel, B.A., Sharma, A., Marshall, L.A., Flanagan, D.C., Cibin, R., Wallace, C.W., Zhao, K., Rem, D., Vera Mercado, J., Aboelnour, M.A. 2022. Improving probabilistic monthly water quantity and quality predictions using a simplified residual-based modeling approach. Environmental Modelling & Software. 156: Article 105499.
Lew, R., Dobre, M., Srivastava, A., Brooks, E.S., Elliot, W.J., Robichaud, P.R., Flanagan, D.C. 2022. WEPPcloud: An online watershed-scale hydrologic modeling tool. Part I. Model description. Journal of Hydrology. 608. Article: 127603.
Mcgehee, R.P., Flanagan, D.C., Nearing, M.A., Srivastava, P. 2021. Chapter 16 - Rainfall erosivity: Essential historical, conceptual, and practical perspectives for continued application. Book Chapter. pp. 373-394.
Pignotti, G., Crawford, M., Han, E., Williams, M.R., Chaubey, I. 2023. SMAP soil moisture data assimilation on water quality and crop yield predictions in watershed modeling. Journal of Hydrology. 617(C). Article: 129122.
Wang, S., McGehee, R.P., Guo, T., Flanagan, D.C., Engel, B.A. 2022. Calibration, validation, and evaluation of the Water Erosion Prediction Project (WEPP) model for hillslopes with natural runoff plot data. International Soil and Water Conservation Research.
Welikhe, P., Williams, M.R., King, K.W., Bos, J.H., Akland, M., Baffaut, C., Beck, G., Bierer, A.M., Bosch, D.D., Brooks, E., Buda, A.R., Cavigelli, M.A., Faulkner, J., Feyereisen, G.W., Fortuna, A., Gamble, J.D., Hanrahan, B.R., Hussain, M., Kovar, J.L., Lee, B., Leytem, A.B., Liebig, M.A., Line, D., Macrae, M., Moorman, T.B., Moriasi, D.N., Mumbi, R., Nelson, N., Ortega-Pieck, A., Osmond, D., Penn, C.J., Pisani, O., Reba, M.L., Smith, D.R., Unrine, J., Webb, P., White, K.E., Wilson, H., Witthaus, L.M. 2023. Uncertainty in phosphorus fluxes and budgets across the U.S. long-term agroecosystem research network. Journal of Environmental Quality. 52(4):837-885.
Williams, M.R., Penn, C.J., Mcafee, S.J. 2022. Source and transport controls on nutrient delivery to tile drains. Journal of Hydrology. 612(B).Article 127146.
Williams, M.R., Penn, C.J., King, K.W., Mcafee, S.J. 2023. Surface-to-tile drain connectivity and phosphorus transport: Effect of antecedent conditions. Hydrological Processes. 37(3). Article e14831.