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ARS Home » Midwest Area » West Lafayette, Indiana » National Soil Erosion Research Laboratory » Research » Research Project #432501

Research Project: Conservation Practice Impacts on Water Quality at Field and Watershed Scales

Location: National Soil Erosion Research Laboratory

2017 Annual Report

Objective 1. Advance the knowledge and improve mathematical representation of processes affecting sediment, nutrient, and pesticide losses in surface and subsurface waters. Subobjective 1.1. Quantify surface and subsurface hydrologic processes affecting transport and transient storage of sediments and chemicals. Subobjective 1.2. Evaluate and improve scientific understanding of nutrient dynamics from the rhizosphere, upland areas, riparian zones, and drainage waterways. Objective 2. Develop methods to reduce pollutant losses from agricultural fields and watersheds, thus protecting off-site water quality. Subobjective 2.1. Develop removal strategies for dissolved phosphorus in drainage water. Subobjective 2.2. Test the impact of established and new conservation practices at the field and watershed scale. Subobjective 2.3. Determine optimal BMPs for control of runoff, sediment, and chemical losses from agricultural fields and watersheds, under existing and future climates. Objective 3. Improve erosion and water quality modeling systems for better assessment and management of agricultural and forested lands. Subobjective 3.1. Develop WEPP model code, including testing and scientific improvement. Subobjective 3.2. Improve ARS soil erosion and water quality model software architectures, interfaces, and databases for end-user model delivery. Objective 4. As part of the LTAR network, and in concert with similar long-term, land-based research infrastructure in the Midwest region, use the Eastern Corn Belt LTAR site to improve the observational capabilities and data accessibility of the LTAR network and support research to sustain or enhance agricultural production and environmental quality in agroecosystems characteristic of the Midwest region. Research and data collection are planned and implemented based on the LTAR site application and in accordance with the responsibilities outlined in the LTAR Shared Research Strategy, a living document that serves as a roadmap for LTAR implementation. Participation in the LTAR network includes research and data management in support of the ARS GRACEnet and/or Livestock GRACEnet projects. Subobjective 4.1. Quantify the relationship between soil quality and water quality under different cropping and management scenarios at the CEAP and Eastern Corn Belt LTAR sites. Subobjective 4.2. Develop techniques that enhance field-to-watershed scale parameterization for improved hydrologic model predictions at the CEAP and Eastern Corn Belt LTAR sites. Subobjective 4.3. Provide data management and services for CEAP and LTAR research sites.

Lab experiments will be used to study topographic driven surface hydraulic processes and soil hydraulic gradient driven subsurface flow effects on sediment and chemical loading and transient storage. Landscape attributes will be used to confirm the lab findings on conditions for sediment and chemical transport processes and processes such as deposition and hyporheic exchange. Field rainfall simulation experiments will be conducted using pan lysimeters to collect leachate to assess the effect of fertilizer placement on phosphorus leaching to subsurface tile drains. Stable water isotopes will be measured at the outlet of a headwater watershed during storm events to identify potential flow pathways and infer potential nutrient sources. We will use lab prototypes to assess the efficiency of steel slag in three potential field-scale phosphorus removal structure configurations, i.e., blind inlet, cartridge, and in-ditch slag dam for testing, and information obtained will be used to design field-scale installations for testing in the St. Joseph River Watershed (SJRW). We will subject steel slag materials to anaerobic conditions, and determine the effects on P solubility, and also explore the feasibility of regenerating materials for P removal structures. Field- and watershed-scale studies will be conducted to assess the impact of conservation practices on water quality, and field-scale studies will be used to assess the impact of drainage design and drainage water management on water quality. The Water Erosion Prediction Project (WEPP), Agricultural Policy Extender (APEX), and Soil and Water Assessment Tool (SWAT) models will be applied to monitored fields and small catchments in the SJRW in northeastern Indiana. Data from General Circulation Models (GCM) will be downscaled to develop modified climate inputs which will allow examination of the impacts of projected future climate on flow and pollutant losses. WEPP development efforts will occur in: Atmospheric CO2 impacts on plant growth; Model response to subsurface tile drainage; Water quality components to simulate nutrient and pesticide pollutant losses. Model development and testing efforts will include maintenance of the WEPP model scientific code, development of user interfaces, model databases, and user support. The WEPP module in the NRCS Cloud Services Innovation Platform (CSIP) software architecture will be made available as an option in the NRCS Integrated Erosion Tool (IET). Additionally, a separate WEPP web-based interface is being developed that allows WEPP to be run using standard NRCS databases. Data will be collected from the new Eastern Corn Belt LTAR sites once they are identified. Real-time weather information, field-measured profile soil moisture data and remotely sensed surface soil moisture content from agricultural fields will be used to improve prediction of surface runoff and tile flow and better understand runoff generation mechanisms. Topographic attributes, soil profile characteristics, and land management will be used to quantify potential for runoff and tile flow (i.e., profile drainage).

Progress Report
The initial experiments on methodology for the study on P uptake by corn and soybeans are currently being conducted in the greenhouse. We were able to identify and test several potentially inert materials for use in this experiment, and based on the results, a 99% pure silica sand was chosen. An automated drip irrigation system for this solution culture system was constructed. Corn and beans are currently being evaluated in this system, and the results currently suggest that 0.35 ppm P in solution is not sufficient for obtaining maximum corn and soybean yield. A comprehensive literature review and meta-analysis on pilot and field-scale P removal structures was conducted. All data were normalized to express data as a function of P loading per unit mass of filter material. This allowed for comparison between studies, after the studies were categorized based on the type of filter media, P source (i.e. P concentration), and type of unit (i.e. retention time). The resulting analysis and discussion are currently in review at the journal, “Water.” Overall, average cumulative P removal by P removal structures was 33%. At least 40 flow-through experiments were conducted on several P sorption materials (PSMs) as part of the characterization process. In addition, a pilot-scale P removal structure was constructed for treating greenhouse wastewater, and is currently being evaluated. All results will be used in consideration and design of the blind inlet to be constructed in the field. We set up a stable water isotope analyzer in the laboratory, developed a standard operating procedure for sample analysis, and have begun analyzing water samples from an edge-of-field site (KC1) and the ALG watershed in the St. Joseph River Watershed in northeastern Indiana. We also conducted an incubation experiment to test the effect of our field sampling strategies (e.g., sample collection frequency and evaporation control measures) on water isotope signatures. The KC1 site was selected for field installation of suction cup lysimeters for isotope analysis. We also collect water samples from groundwater wells, precipitation, and tile drains at the site on a weekly basis. At the AS1 and AS2 sites in the St. Joseph River Watershed in northeastern Indiana, new tile drainage has been installed. With the new tile drainage, we will be able to test the effect of drainage design (contour vs. traditional installation), increasing tile density (random tile drainage vs. systematic tile drainage), and drainage water management over the next several years of the project. Working with the ARS in Columbus, Ohio, we also successively completed a rainfall simulation study to determine the impact of fertilizer placement on phosphorus leaching. Data analysis and manuscript writing using the data from the rainfall simulation are ongoing. First year of cover crops and gypsum were implemented at the DPAC (Davis Purdue Agricultural Center) field treatments sites (+ control). Runoff events have occurred and samples were collected from field sites with blind inlets. Also, water samples using suction lysimeters are being collected from the tillage x crop rotation experimental sites. Major efforts have continued with the Natural Resources Conservation Service (NRCS) as that agency moves to implement the Water Erosion Prediction Project (WEPP) model in their field offices for conservation planning activities. Project staff at the NSERL and cooperators from Purdue University have worked closely with the NRCS agronomists on developing the interface software, testing and modifying the databases, and modifying the WEPP model code as necessary to provide the system that NRCS desires. The group has completed testing for 21 locations in the U.S., and the group testing the model and interface has expanded to include more regional and state agronomists. A WEPP NRCS CSIP (Cloud Services Integration Platform) software service is undergoing testing by NRCS Regional Agronomists. This software also includes WEPP databases customized by NRCS. The module is also undergoing testing by Colorado State University as a component of Integrated Erosion Tool (IET) which is used in NRCS desktop conservation planning software. The WEPP science portal web interface is being used by NRCS testers to setup model simulations, interpret outputs and evaluate database parameters. Updates to the user interface and databases are incorporated based on NRCS testing feedback. Testing of real-time data transmission from NSERL-CEAP sites to national database is underway.

1. Phosphorus removal technology in a comprehensive volume. Excessive phosphorus (P) in agricultural drainage waters has caused environmental problems world-wide. Treatment technologies to remove P in a real-time setting require a combination of applied science and engineering in chemistry, material science, hydrology, and hydraulics. An ARS scientist at West Lafayette, Indiana recently published the first comprehensive book on the design and construction of P removal structure. This publication makes the P removal technology more readily available to anyone who plans to build a system to minimize the excessive P problem.

2. Connecting empirical and process-based erosion prediction models. Soil erodibility is a term used to quantify how erodible a soil is. ARS scientists at West Lafayette, Indiana have developed an empirically-based Universal Soil Loss Equation (USLE) and a process-based Water Erosion Prediction Project (WEPP) model. Both models are used extensively world-wide for erosion assessment and conservation planning. Nevertheless, a question remains as whether the erodibility terms used in these two models are related because the WEPP erodibility can be derived quickly through controlled laboratory or field experiments while the USLE erodibility requires long-term natural runoff plot data. Using soils from Washington, South Dakota, Indiana and Vermont, we found that it is feasible to use measured WEPP erodibility to derive USLE erodibility. On the other hand, we also found that soil erodibility is dynamic and it can change as surface condition varies or be affected by long-term cropping-management history. These findings provide a guidance on where the current erosion prediction models need to be improved to more accurately assess erosion from agricultural fields.

Review Publications
Deviren Saygin, S., Huang, C., Flanagan, D.C., Erpul, G. 2017. Process-based soil erodibility estimation for empirical water erosion models. Journal of Hydraulic Research IAHR. doi:10.1080/00221686.2017.1312577.
Li, S., Gitau, M., Engel, B.A., Zhang, L., Du, Y., Wallace, C., Flanagan, D.C. 2017. Development of a distributed hydrologic model to facilitate watershed management. Hydrological Sciences Journal. 62:11:1755-1771. doi:10.1080/02626667.2017.1351029.
Liu, Y., Engel, B.A., Flanagan, D.C., Gitau, M.W., McMillan, S.K., Chaubey, I., Cherkauer, K.A. 2017. A review on effectiveness of best management practices in improving hydrology and water quality: Needs and opportunities. Science of the Total Environment. 601-602:580-593. doi:10.1016/j.scitotenv.2017.05.212.
Christianson, L.E., Lepine, C., Sibrell, P.L., Penn, C.J., Summerfelt, S.T. 2017. Denitrifying woodchip bioreactor and phosphorus filter pairing to minimize pollution swapping. Water Research. 121:129-139.