Location: National Soil Erosion Research2019 Annual Report
1a. Objectives (from AD-416):
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.
1b. Approach (from AD-416):
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).
3. Progress Report:
Several field-scale phosphorus (P) removal structures were constructed using steel slag as the P sorption material. The first structure was combined with a blind inlet. The blind inlet captured surface water at the site and was plumbed into the buried tile drain P filter, which receives an average of 4 million gallons of water per year. This structure removed approximately 50 to 70 lbs. of dissolved P in the first month from rainfall events that occurred within days of completion and after fertilizer application to the field. However, P removal has since decreased. A second structure was a ditch-filter containing approximately 50 tons of steel slag. While this structure was highly efficient for about 4 months, it is no longer removing P. Efforts are underway to explore the reason for the decreased P removal and techniques to improve the P sorption efficiency. Two other P removal structures were also installed in a swine farm and their performance in P removal is being monitored. Besides treating agricultural drainage water, a P removal structure is being designed for a waste water treatment facility due to new and stringent regulations for allowable P discharge. Regeneration of P sorption materials would significantly decrease long-term costs associated with P removal structures. Different materials are being assessed, using flow through cells simulating the condition in a field installation, for the potential to be regenerated in-situ after the material become saturated with P. Specifically, manufactured P sorption materials have shown excellent chemical and physical properties for potential use in P removal structures, but high cost often excludes them from practical consideration. On the other hand, by-products can often be obtained for a much lower cost. Metal shaving, a very low-cost industrial by-product, shows tremendous potential for P removal. Pilot scale results show great potential for field use. Through cooperation with the American Society of Agricultural and Biological Engineers, American Society of Agronomy, and the USDA-Natural Resources Conservation Service, ARS scientists at West Lafayette, Indiana, are developing a series of training modules on the design and construction of P removal structures. There will be two sets of modules; one for lay-people and the other for engineers who will design the structures. Collection of water isotope data from both field and watershed scales in the St. Joseph River watershed is ongoing. To supplement field and watershed monitoring, a laboratory experiment was also designed to assess water transport pathways. Undisturbed soil cores were exposed to simulated rainfall events. Bromide, chloride and water isotope tracers were used to elucidate flow pathways through the soil. Experimental data collected under controlled conditions will support better interpretation of the field data. Flow characteristics for 549 storm events over a 12-year period for two closed depressions in northeastern Indiana were examined to assess the effect of replacing a traditional tile riser with a blind inlet on depression hydrology. Results showed that blind inlet infiltration rates declined over time. With extensive tillage, blind inlets may have a service life of 8-10 years before infiltration capacity becomes greatly reduced; the service life may be longer with no-tillage. Blind inlets did not influence the frequency of flow, but they may increase or decrease the length of ponding in fields compared to a tile riser, depending on the amount of tile drainage in the fields. The amount of subsurface drainage in a field should be considered prior to installing blind inlets in closed depressions. Cover crops, manure, and gypsum treatments were implemented at field plots at the Davis Purdue Agricultural Center (DPAC) in east central Indiana. Water samples were collected during the 2018 growing season for analysis of soluble nutrients and pesticides. A rainfall simulation study is planned for the 2019 growing season to investigate the effect of gypsum on surface losses of nutrients from liquid manure with the following treatments: 1) co-application of manure and gypsum; 2) application of gypsum followed by manure; and 3) application of manure followed by gypsum. Several computer simulation studies have been conducted in the CEAP watersheds in northeastern Indiana, utilizing monitored flow and chemical losses for model calibration and validation, and then simulation of the effects of projected future climate change. Both the WEPP and SWAT models have been assessed for their capabilities in predicting runoff, stream flow, and sediment and chemical transport. Activities on WEPP include testing and enhancement of the subsurface drainage component, and expansion of WEPP-Water Quality model to allow simulation of multiple overland flow regions. Additionally, a version of WEPP that accounts for increased levels of atmospheric carbon dioxide levels is being tested by cooperators at the ARS El Reno, Oklahoma, location. This version will be especially useful in future climate change simulation studies. An erosion model comparison study was conducted with scientists at the National Sedimentation Laboratory (Oxford, Mississippi), examining applications of the WEPP and Revised Universal Soil Loss Equation version 2 (RUSLE2) models within the state of Iowa. The first component of the study is examining climate inputs to both models, derived from observed weather station data in Iowa. Preliminary results indicate that simulated climate inputs to WEPP are somewhat more vigorous than erosion predictions obtained using direct inputs of the observed 15-min precipitation depths. Without accounting for the potential bias from the climate input, WEPP and RUSLE2 had similar soil loss predictions (with -2 to +2 Tons/acre/year differences) in about half the simulations. For conventional tillage systems, WEPP tended to estimate greater soil losses than RUSLE2, while for no-till systems (especially soybeans) RUSLE2 tended to estimate greater soil losses than WEPP. Efforts are underway to fully understand the differences between these two models and whether changes are needed. The WEPP NRCS Cloud Services Integration Platform (CSIP) software service continues to undergo testing by NRCS. The databases allow commonality between the Wind Erosion Prediction System (WEPS) and WEPP, making it easier for NRCS to develop land management scenarios that are compatible with both models. The WEPP NRCS CSIP module is being tested by Colorado State University as a component of the Integrated Erosion Tool (IET) which is used in NRCS desktop conservation planning software. The WEPP NRCS CSIP software service integrates various components and provides a good baseline for future work in working with ARS natural resource models. Work has continued on organizing and importing the CEAP data that the NSERL collects into the Aquarius water data management system. This has included putting boundary checks on the data and being able to visualize areas where data may not be correct. Additional instrumentation is expected to be installed in the second half of 2019. A local area network was configured to support the additional instrumentation. Scripts were deployed to allow real-time weather data access from the USDA National Agricultural Library. Improvements were made to the Climate Generator (CLIGEN) web service to adjust the precipitation frequency statistics when using the monthly gridded PRISM climate dataset. Based on previous research this allows for better estimation of the storm characteristics when using the PRISM data by accounting for additional rain days if the monthly precipitation increases. Improvements were made to the WEPP web service to allow for the simulation of trees/shrubs. This included database updates along with web service and model updates. These changes allow simulations of trees/shrubs to more closely match the existing RUSLE2 behavior. The Phosphorus Removal Online Guidance (Phrog) software is a set of Mathematical routines for designing phosphorus removal structures. This software is being rearchitected to work in a web environment. The project is about 50% completed, the resulting website will allow external users to work with the design software.
1. Improving our understanding how different phosphorus filter materials can remove dissolved phosphorus. Excessive dissolved phosphorus losses have been attributed as the cause of the recent re-eutrophication of Lake Erie and poor water quality in other surface waters throughout the world. Different phosphorus sorption materials are utilized for filtering dissolved phosphorus and the sorption mechanisms impact decisions on how to best design phosphorus removal structures. ARS scientist at West Lafayette, Indiana, and cooperators used X-ray spectroscopy to measure the forms of phosphorus found on phosphorus filter materials that were previously used in field-scale phosphorus removal structures. Materials included steel slag, coated steel slag, mine-drainage residuals, fly-ash, and drinking water treatment residuals, and were rich in calcium, aluminum, iron, or some combination. The results showed that several of the materials were removing phosphorus by multiple mechanisms, others simply by calcium phosphate precipitation or sorption onto aluminum and iron minerals exclusively. This is important because certain conditions, such as pH, will have a direct impact on the efficiency of those phosphorus removal mechanisms which will thereby impact the choice of filter material for certain circumstances. Stakeholders involved in promoting, constructing, or designing phosphorus removal structures can use this information to make more informed decisions with regard to choosing optimum phosphorus sorption materials.
2. The fill-spill hydrology of drained and farmed closed depressions. Drained and farmed depressions (i.e., “potholes”) are commonly found across the glaciated Midwestern U.S. and can facilitate elevated nutrient loading due to their inherent hydrologic connectivity with surface waters. Using long-term edge-of-field data, ARS researchers in West Lafayette, Indiana, examined the effect of rainfall characteristics (e.g., amount, intensity) and antecedent soil moisture on surface runoff and subsurface tile drainage in a drained closed depression. Study results showed that large rainfall amounts did not always produce flow. Neither surface runoff nor subsurface tile flow was observed unless the rainfall amount was sufficient to increase soil moisture to near saturation. Nutrient loads from the monitored depression were closely related to water discharge suggesting that nutrient loss from drained and farmed depressions may be able to be predicted using soil moisture measurements and rainfall forecasts. Findings also highlight the importance of understanding hydrologic processes in drained and farmed depressions for developing improved water and nutrient management strategies.
3. Developed an updated climate database for use with CLIGEN and WEPP models. Use of physically-based soil erosion prediction models require accurate and up-to-date climate inputs. The current (1995) climate database used for the Water Erosion Prediction Project (WEPP) model was developed with information through 1992, and variable years of record. ARS scientists and Purdue University cooperators at West Lafayette, Indiana, examined the effects of updating the database for the CLImate GENerator (CLIGEN) that creates daily climate inputs for the WEPP erosion model. The updated database contains statistical information from observed weather at 2765 stations in the United States, from 1974-2013. Results showed increased annual precipitation and minimum temperatures across most of the U.S. while maximum temperatures only increased in the western half of the country and in the Northeast. The updates in the climate database also resulted in greater WEPP runoff and erosion predictions in much of the U.S. These results impact conservation agency staff, farmers, scientists, and others involved in erosion prediction and soil conservation planning activities.
4. Design and demonstration of the construction of a phosphorus removal structure. Phosphorus (P) removal structures are intended for reducing phosphorus pollution that causes eutrophication of surface water bodies such as Lake Erie. Reducing eutrophication to surface waters is important to the economy, ecosystem, drinking water treatment, and those who utilize them for recreation. While phosphorus removal structures are useful in helping to filter dissolved phosphorus before it reaches a water body, there is a need to disseminate this new conservation practice to farmers, non-profits, state agencies, and to help train potential service-providers. ARS scientists at West Lafayette, Indiana, designed a large underground tile drain P filter using 60 tons of slag, on a large swine farm near Holland, Michigan. This was the largest tile drain filter ever constructed using tanks. A journalist from the American Society of Agronomy filmed and documented the process, for future use in several training modules. At least twenty people came to see the construction of the unit, representing non-profit organizations such as Friends of Lake Macketawa, the Outdoor Discovery Center, American Society of Agronomy, and the American Society of Agricultural and Biological Engineers, as well as USDA Natural Resources Conservation Service engineers and conservationists. While some participants released several pictures to social media, several groups contacted the ARS for more information, including Drainage Contractor Magazine. This effort helped not only to train people interested in how to construct P removal structures, but it resulted in the dissemination of the technology to an unknown number of people. Increased adoption of this practice, and training of people for providing the service, will decrease dissolved phosphorus loading to surface water bodies and improve water quality.
5. Repeated freezing and thawing over winter increases soil erosion. Over winter months, the repeated freezing and thawing can change soil surface properties significantly enough to affect aggregate stability and soil erodibility. Since water expands when it freezes, the freeze-thaw (F-T) effect on soil is also affected by the soil moisture content at the time of freezing. In a laboratory rainfall simulation experiment, ARS scientists at West Lafayette, Indiana, and Chinese cooperators studied how the number of F-T cycle and soil moisture content at freezing affected runoff and erosion. The results show that both increased number of F-T cycle and increased soil moisture content caused the increase in runoff and sediment loss, but the soil moisture had more profound effect. This research fills a gap in the current literature about how repeated freeze-thaw affects erosion processes and the results can be used to improve assessment of runoff and soil loss in regions where winter processes are significant.
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