Location: National Soil Erosion Research Laboratory2018 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).
A best management practice utilizing biochar to filter atrazine from non-point drainage with pollution-control structures such as blind-inlets was developed. Results from a calorimetry method showed that atrazine removal with biochar occurs through different mechanisms that occur at different rates. Results of flow-through tests supported the calorimetric kinetics observations, with a 300-sec contact time removing much more atrazine compared to 45 sec, while 600 sec improved little compared to 300 sec. Based on the flow-through results, an annual atrazine removal goal of 50%, and typical Midwestern U.S. tile drainage conditions, a pollution-control structure implementing this biochar sample would require 32 and 4 Mg for a design utilizing a contact time of 45 and 300 seconds, respectively. These results will be used to design pollution control structures to reduce atrazine concentrations with biochar, but more research is needed to determine degradation of the atrazine sorbed to the biochar. Lab experiments were conducted to determine the potential for utilizing steel slag fines in a filter design that allows for water to flow from the bottom-upward instead of the traditional top-downward. The results were promising as no clogging occurred with our pilot-scale unit, due to the flocculated precipitant being saturated in water at all times, preventing it from drying and forming a solid that could clog the filter. When tested on a small scale, this material has the potential to remove dissolved P for over 30 years. Future work is to be conducted on scaling up to the field. Constructed a phosphorus (P) removal structure in a greenhouse for the purpose of filtering dissolved P from the drainage water of pots. Various ornamental, fruit, and vegetable plants were grown in traditional greenhouse media, but all drainage water from the pots was collected and automatically filtered through a P sorption material (PSM) bed of mine drainage residuals (MDRs), which are a by-product of treating acid mine drainage pollution from coal mines. The horticultural operation produced extremely high concentrations of dissolved P (around 20 mg/L), and also elevated concentrations of copper (Cu) and zinc (Zn). P and Cu removal is still nearly 100% after one year of operation, while Zn removal was much less (cumulative removal around 25%). These results that will aid greenhouse managers by providing a means of reducing their negative environmental impact through use of these filters. A series of experiments involving application of oil base “mud” (OBM) to laboratory soil columns at various rate under several worst-case scenario rainfall regimes showed that total petroleum hydrocarbons (TPH) degraded 35% after 60 days, and benzene, toluene, ethylbenzene, and xylene (BTEX) concentrations in leachate were undetectable at 28 days after application. Even when BTEX leachate was at its highest, benzene concentrations were low enough to pass drinking water quality standards. Based on the results, there is little risk of BTEX leaching from land applied OBM. Using an isotope analyzer, an incubation study was completed to develop a sampling protocol for collecting water in the field that minimizes the uncertainty in isotopic signatures that can result due to evaporation. Analysis to stable water isotopes was also a critical component of a rainfall simulation study investigating the effect of fertilizer placement on phosphorus leaching (subobjective 1.2). Results from the rainfall simulation study showed that commercial fertilizer that was either incorporated into the soil using either tillage or injection was less susceptible to loss compared to fertilizer that was broadcast on the soil surface. New tile drainage systems have been installed at two edge-of-field monitoring sites in collaboration with a local tile contractor and an agricultural drainage supply company (subobjective 2.2). The drainage system on one field was designed according to regional best practices, while the drainage system on the other field was designed specifically for water management and included four water control structures. Baseline hydrology and water quality data collection are ongoing at both of these fields to evaluate both drainage design and drainage water management practices. To better understand the subsurface runoff generation mechanisms in tile drained fields, a hanging water column system was also designed and constructed that allows a constant tension to be applied to suction cup lysimeters (subobjective 4.2). Five hanging water columns have been installed in two locations in an agricultural field in northeastern Indiana, with suction cup depths ranging from 10 to 80 cm. Precipitation collectors, groundwater wells, and tile drain monitoring in conjunction with the suction cup lysimeters will provide the data to quantify dominant flow pathways to tile drains. Under the Conservation Effects Assessment Project (CEAP), the Before-After-Control-Impact (BACI) statistical analysis is used to compare the impact of cover crops on pesticide and nutrient losses from closed depressions with blind inlets. Cover crops were implemented in a treatment watershed identified as ADW after harvest in 2016 and 2017, while a neighboring watershed identified as ADE served as control. Water samples were collected from fall 2015 to spring 2018 for the analysis of nutrients and pesticides. The data from fall 2015 to fall 2016 will serve for the “Before” period, whereas the data from winter 2016 to spring 2018 will serve for the “After” impact of cover crops. Preliminary data for the “Before” period indicates that the concentrations of nutrients and pesticides from both closed depressions are similar, including atrazine, S-metolochlor, and ammonium-N; but higher concentrations of nitrate-N, and phosphate-P were observed from the ADW closed depression. We need to analyze samples from Fall 2017 to Spring 2108 for the final report. This experiment has now been terminated to accommodate the implementation a P removal structure at the ADE site. In Spring 2019, a blind inlet with biochar and other sorbing material to remove pesticides from water at the ADW site is being planned. Water Erosion Prediction Project (WEPP) project staff and Purdue University cooperating scientists have worked closely with the Natural Resources Conservation Service (NRCS) agronomists on developing interface software, testing and modifying the databases, and modifying the WEPP model code as necessary to provide the system that NRCS desires. NRCS is conducting extensive testing with regional and state agronomists, and expects to fully implement WEPP in their field offices by the end of 2018. A WEPP NRCS Cloud Services Integration Platform (CSIP) software service is undergoing testing by NRCS with scheduled deployment in 2018. This software also includes WEPP databases customized 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 also undergoing testing by Colorado State University as a component of the 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. The WEPP web interface will be used by NRCS and other users such as technical service providers.
1. Using biochar for filtering atrazine from water: kinetics and thermodynamics. Atrazine is one of the most common broad-leaf herbicides used in the world. However, due to extensive use for many years, atrazine often appears in surface and groundwater. Biochar is a charcoal-like material produced from pyrolysis of biomass. Biochar has shown potential for sorption of atrazine from solution. There is an interest in developing best management practices utilizing biochar to filter atrazine from non-point drainage with pollution-control structures such as blind-inlets. ARS researchers at West Lafayette, Indiana, using a calorimetry method, learned that atrazine removal with biochar occurs through different mechanisms that occur at different rates. This is important because pollution-control structures are designed to achieve a specified contact time between the water and the filtration media. Results of flow-through tests supported the calorimetric kinetics observations, with a 300-sec contact time removing much more atrazine compared to 45 sec, while 600 sec improved little compared to 300 sec. Based on flow-through results, annual atrazine removal goal of 50%, and typical Midwestern U.S. tile drainage conditions, a pollution-control structure implementing this biochar sample would require 32 and 4 Mg for a design utilizing a contact time of 45 and 300 seconds, respectively. This research will be utilized in proper design of pollution control structures that aim to reduce atrazine concentrations with biochar.
2. Increasing the efficiency of steel slag phosphorus filters. Excessive transport of dissolved phosphorus (P) to surface waters directly contributes to water quality degradation, such as the eutrophication of Lake Erie and Chesapeake Bay. Phosphorus removal structures are a new technology that utilizes industrial by-products in a landscape-scale filter. Steel slag is one of the most popular P sorption materials (PSMs) due to its availability and ability to conduct water at high flow rates. However, slag must first be sieved in order to achieve this permeability, and much of the P removal ability is found in the fines. On the other hand, the fine fraction often produces excessive amounts of precipitant that can clog the filter upon drying. ARS researchers at West Lafayette, Indiana, explored the potential for utilizing the slag fines in a filter design that allows for water to flow from the bottom-upward instead of the traditional top-downward. The results appear to be promising as no clogging occurred with our pilot-scale unit, due to the flocculated precipitant being saturated in water at all times, preventing it from drying and forming a solid that could clog the filter. When tested on a small scale, this material has the potential to remove dissolved P for over 30 years. This research provides guidance for how to properly design P removal structures that are economical and efficient at improving water quality.
3. Application of mine drainage residuals for treating horticultural greenhouse waste water. Excessive dissolved phosphorus (P) transport not only occurs in the context of agronomic cropping systems, but also for horticultural operations. This transport of P contributes to the eutrophication of water bodies such as the Gulf of Mexico and Lake Erie. ARS researchers at West Lafayette, Indiana, constructed a P removal structure in a greenhouse for the purpose of filtering dissolved P from the drainage water of pots. Various ornamental, fruit, and vegetable plants were grown in traditional greenhouse media, but all drainage water from the pots were collected and automatically filtered through a P sorption material (PSM) bed of mine drainage residuals (MDRs), which are a by-product of treating acid mine drainage pollution from coal mines. The horticultural operation produced extremely high concentrations of dissolved P (around 20 mg/L), and also elevated concentrations of cooper (Cu) and zinc (Zn). P and Cu removal is still nearly 100% after one year of operation, while Zn removal was much less (cumulative removal around 25%). This study provides results that will aid greenhouse managers by providing a means of reducing their negative environmental impact through use of these filters.
4. Safely disposing of oil and gas drilling waste on agricultural soils. Increases in oil and gas drilling have resulted in large quantities of oil base “mud” (OBM) to be disposed of. Land application of OBM to agricultural land is a common disposal technique that presents agronomic and environmental challenges since the material is rich in total petroleum hydrocarbons (TPH). Leaching of lower molecular weight hydrocarbons, mainly benzene, toluene, ethylbenzene, and xylene (BTEX), is a concern due to their relatively high solubility in water. In a series of experiments that involved application of OBM to laboratory soil columns at various rate under several worst-case scenario rainfall regimes, ARS researchers at West Lafayette, Indiana, found that TPH degraded 35% after 60 days, and BTEX concentrations in leachate were undetectable at 28 days after application. Even when BTEX leachate was at its highest, benzene concentrations were low enough to pass drinking water quality standards. Based on the results, there is little risk of BTEX leaching from land applied OBM. This information is especially useful to environmental regulators, oil and gas industry, and agriculture producers considering have OBM applied onto their land.
5. Identified dominant mechanisms for nutrient delivery in tile-drained fields and watersheds. Nutrient loss from agricultural fields and watersheds is often the primary cause of water quality impairment of surface water bodies across the U.S; thus, identifying and quantifying nutrient transport pathways is critical for mitigating downstream impacts. Using edge-of-field and in-stream data, ARS researchers in West Lafayette, Indiana, and Columbus, Ohio, revealed the dominant transport pathways and mechanisms controlling nutrient delivery to downstream waterbodies across a range of flow conditions in intensively managed fields and watersheds with artificial subsurface drainage. Nutrient loss primarily occurred during large storm events, with the majority of nutrient export occurring via the subsurface tile drainage network. Both in-field and in-stream processes affect nutrient concentrations and loads, with findings highlighting the need to implement conservation practices that consider in-field nutrient and water management as well as in-stream processes.
6. Quantified transport and fate of fertilizers applied to fields with subsurface drainage using isotopic tracers. Applying fertilizers and manures to agricultural fields increases the risk of nutrient loss to downstream surface water bodies. Identifying the source and flow pathways for nutrient loss are needed to better implement conservation practices to reduce these losses. Using isotopic tracers, ARS researchers in West Lafayette, Indiana, in partnership with University of Kentucky and United States Geological Survey (Menlo Park, California) collaborators quantified phosphorus loss to subsurface tile drains from recent (e.g., less than one day) and legacy (e.g., greater than 10 years) fertilizer applications. Phosphorus losses to tile drains immediately after fertilizer application were largely a function of fertilizer placement and the effect of tillage on preferential flow pathways through the soil. Novel phosphate stable oxygen isotopes also revealed that elevated phosphorus losses in drainage water from a study field were likely supplied by poultry litter applications that occurred over 10 years prior to the monitoring period. Findings showcase both the utility of isotopic tracers for improving interpretation of water quality data and the challenge of mitigating phosphorus loss in tile-drained landscapes.
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