Objective 1: Determine linkages between stream water quality and field characteristics through field and watershed scale studies. 1a: Improve the Phosphorus (P) Index on claypan soils. 1b: Determine nutrient fluxes from surface drained land in the lower Mississippi River basin. 1c: Assess stream water quality within the northern Missouri/southern Iowa Region (NMSIR). Objective 2: Assess the effectiveness of conservation practices to mitigate the impacts of agriculture on water quality in the Central Mississippi River Basin. 2a: Assess the effect of grasses and vegetative buffers on the fate of organic contaminants. 2b: Determine effectiveness of buffer strips, crop rotations and cover crops. Objective 3: As part of the LTAR network, and in concert with similar long-term, land-based research infrastructure in the Central Mississippi River Region, use the Goodwater Creek Experimental Watershed 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 Central Mississippi River basin. 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. 3a: Establish an observatory for weather and discharge monitoring representative of the CMRB. 3b: Establish and conduct an experiment comparing the performance of two farming systems: one business as usual (BAU) that reflects the dominant agricultural practices in the CMRB and one aspirational (ASP) that is hypothesized to result in less adverse environmental impacts and improved economic output. 3c: Investigate greenhouse gas (GHG) as a function of crops and top soil depth. 3d: Assess denitrification in claypan soils. 3e: Assess climate change impacts in CMRB.
Increased sustainability of agriculture in the Mississippi River Basin will be studied at field, farm, and watershed scales. This research will focus in understanding how alternative farming systems can become more resilient and sustainable through increased food production, less environmental impacts on water and air resources, and climate regulation. The overall goal of this project is to improve understanding of, and help manage water resources for sustainable agricultural production in the Central Mississippi River Basin (CMRB). Emphasis is given to long-term study, i.e., 50 year window. Thus, we will design and implement a monitoring infrastructure for this research. The project will focus on edge of field studies that link water quantity and quality to field characteristics, soil, crop and agronomic management practices, and conservation practices (e.g., buffer strips); on watershed studies that link inherent vulnerability caused by soils and topography to stream water quality; on regional studies that broaden the scope of our plot, field, and watershed research. The observatory of the Long-Term Agroecosystems Research (LTAR) infrastructure will provide long-term data of weather and stream flow in our research watershed to reveal possible manifestations of climate change, as well as interpret experimental observations and drive simulation models. The Common Experiment, within the LTAR project, will compare production, surface runoff quantity and quality, soil health, and biological indicators between “Business-As-Usual” (BAU) and Aspirational (ASP) systems and inform environmental (e.g., crop residue reducing soil erosion potential) and economic (e.g., crop yield and quality) aspects of relative sustainability of the two systems. Long-term assessment of water, carbon, and nutrient budgets will show how the respective components are affected by climate change and management. Measurement of instantaneous energy, water, and carbon fluxes will provide needed data for full interpretation of the differences observed between these management systems. Short term plot studies are included to investigate processes, including soil emissions of greenhouse gases and denitrification, where interaction between management (e.g., tillage, crop type, fertilizer) and soil landscape properties (e.g., landscape position, soil horizonation) may be a significant factor. These plot studies will provide guidance to design and implement the long-term nfrastructure.
Analysis of Phosphorus Index values and simulations results from the Agricultural Policy/Environmental eXtender (APEX), an ARS model, runs to improve the P Index on claypan soils (Obj. 1a) was initiated with the newest version of APEX (APEX1501). This version provides results that match crop yields as a function of the depth to the claypan better than the previous APEX0806 version. However, parameterization of this version has been challenging and we are in contact with the APEX developers for guidance. In collaboration with cooperators, we finalized publications that present the results of our evaluation of the Natural Resources Conservation Service (NRCS) Soil Vulnerability Index (SVI, subordinate project), which classifies inherent soil vulnerability of cropland to loss of sediment and nutrients by runoff and leaching. These conclusions will be used in our improvement of the Phosphorus Index (Obj. 1a), and in a follow-up project with NRCS and collaborators to improve upon the current version of the SVI to link field characteristics to runoff and stream water quality (Obj. 1b). All water quality monitoring in northern Missouri streams is completed. However, analysis of all the samples (first and second year) is delayed (Obj. 1c). Two separate 60-day soil degradation studies were completed; one for the veterinary antibiotic, lincomycin, and the other for estrogen as affected by vegetation. Analyses to determine amounts of both compounds remaining are on-going with completion expected in Fall 2020. New results regarding atrazine degradation studies are near completion. Root extracts from eight switchgrass varieties were assessed for ability to degrade atrazine and significant differences were found between varieties. Attempts to identify degrading phytochemicals failed, but results suggested unstable compounds were responsible for the observed degradation, refuting our original hypothesis that switchgrass produces significant quantities of stable degrading phytochemicals. In addition, we completed sorption studies of a previously documented atrazine degrading compound – known as 2-ß-D-glucopyranosyloxy-4-hydroxy-1,4-benzoxazin-3-one (DIBOA-Glc or DBG) - isolated from eastern gamagrass. Results showed DBG strongly binds to soils and pure clays. In addition, when either DBG or atrazine were bound to clay, atrazine degradation was not observed, indicating that sorption of either completely inhibited the reaction between DBG and atrazine. Spectroscopic analyses are pending to determine the types of chemical bonds by which DBG binds to clays. Monitoring and upkeep of Long-Term Agroecosystem Research (LTAR) cropping systems are continuing, including all field operations for the cropping systems and plant, soil, water, and air sampling at three scales: small plots, large plots, and fields (Obj. 2b, 3a, 3b). The replacement of pressure transducers by flow bubblers is fully completed. Precipitation, flow data, and completed water quality analyses at field and stream sites through 2018 were certified. While protocols require uploading data in Sustaining the Earth's Watersheds, Agricultural Research Data System (STEWARDS) by Q1 of FY20, there were problems with the upload, which was only partial (Obj. 3a). We expect these problems to be resolved with the cooperation of the STEWARDS developers. Water quality analyses of water samples are completed up to August 2018. Delays in hiring and equipment malfunctions have caused delays and created a backlog. Flow and climatic data for 2019 are proceeding through quality analysis per established procedures. Flow data and samples from 2020 are being collected. Samples are analyzed within the limits of what is possible. Completed and published a paper on water budgets across the LTAR network. (Obj. 3a). Data management is progressing to ensure data quality, security, and accessibility. Current weather data from the Central Mississippi River Basin are uploaded to the National Agricultural Library on an hourly basis. An automated early warning system of failing monitoring infrastructure or data transfer is operational and has proven useful to shorten or avoid periods of missing data. Software for all phases of the climatic data QA/QC is complete and implemented. Certification of climate data collected since 2015 with this software is ongoing and provides a real case to proof, debug, and improve the software. Searched for and hired a new data manager who will start at the beginning of July. (Obj. 3a). Energy, carbon, and water vapor flux data are available pending post-processing (Obj. 3b). Post-processing of flux data is taking longer than expected but most components are functional in test mode. Data exist from the aspirational management field (established 6/2015), the business-as-usual field (6/2016), reference native prairie (10/2017) sites, and Missouri Ozarks AmeriFlux (MOFLUX – established 2002) site as another, forested, reference. Production and associated management data have been collected and certified for the Aspirational (ASP) and Business-as-usual (BAU) cropping systems, at the field and plot scales, up to and including 2019. We completed the process of redefining the ASP crop rotation to address implementation and soil remediation issues. The new system includes a hay-crop year along with three grain-crop years (corn, soybean, wheat). The first hay year will be 2021. (Obj. 3b). Aboveground net primary productivity, yield/harvest index, plant tissue chemistry, and soil microbial abundance and diversity are complete and certified (Obj. 3b). A manuscript on soil health (ASP versus BAU) is in progress and substantially complete. Crop phenology images are transmitted automatically for use by the phenology group. A collaborator is collecting plant diversity data. A complete and valid weekly Green House Gas (GHG) data set for the BAU and ASP plots during one growing season was obtained (Obj. 3c). However, we were not able to obtain high quality data that characterize GHG emissions following rainfall events. Completed portions of a third year of soil oxygen, temperature, and soil moisture at three locations and two depths within BAU and ASP fields. Use of these data to develop relationships for up-scaling denitrification (transformation of nitrous oxide into nitrogen gas) estimates to field scales is in progress and will be near full completion in FY20. (Obj. 3d). Manuscripts in progress include: 1) spatial distribution and landscape dependence of potential and actual denitrification from BAU and ASP fields; 2) assessment of RNA-based methods for quantifying a key denitrification enzyme in soils and its correlation to potential and actual denitrification; and 3) field-scale estimates of denitrification for BAU and ASP fields. While work with collaborators implemented to assess water availability and productivity in the Goodwater Creek Experimental and Mark Twain Lake watersheds under varying climate (Obj. 3e) is complete, additional manuscripts from the work completed under this agreement are underway. A manuscript on the prediction of future drought risk in the region is in revision after a first review. A manuscript on the balance between future water demand and availability is near completion, with an FY20 expected submission date.
1. Developed water budgets across the Long-term Agroecosystem Research (LTAR) network. Understanding how management of intensified agricultural production and climate may affect soil water storage and water movement in agricultural landscapes is critical to using water more efficiently and sustainably. However, this understanding is largely incomplete. ARS scientists in Columbia, Missouri, along with collaborators at each of the 18 LTAR sites, developed agricultural site water budgets, which account for all of the inputs and outputs of water on an average annual basis. The network covers a range of precipitation from 240 to 1400 mm per year, evaporation and plant water uptake from 228 to 1080 mm per year, and surface runoff and subsurface flow from negligible to 560 mm per year. However, uncertainties of where all the water is going remained high, in part because measurement of soil water storage and downward movement of water was limited to short periods or was estimated by other means. More accurate measurement of the major inputs and outputs, and direct measurement of water content and percolation are keys to understanding how agricultural lands affect water movement. Identification of these data gaps will guide future research across the LTAR network and provide opportunities to leverage the network to improve understanding of water movement and storage across agricultural landscapes. Characterization of agricultural water budgets across the United States contributes to the body of water budgets frequently developed for natural environments and is a useful addition for hydrologists, hydrologic modelers, and water resource managers. The LTAR modeling group is using these water budgets to validate their models.
2. Validated an index to classify cropland vulnerability to environmental losses. Knowledge of cropland vulnerability to loss of pollutants to streams provides opportunities to adapt cropping systems to this vulnerability and plan conservation needs in a field or region. ARS scientists in Columbia, Missouri, and other ARS, NRCS, and University of Missouri cooperators evaluated the accuracy and the usefulness of the Natural Resources Conservation Service (NRCS) Soil Vulnerability Index (SVI), which characterizes a soil’s vulnerability to loss of sediment and nutrients from cultivation. The scientists evaluated the index across 13 watersheds across the United States, based on their expertise in these watersheds, application of physical principles, measured sediment and nutrient stream loads, and model simulations. While the SVI worked well in areas with a range of slopes and soils, additional factors such as slope length, depth to a restrictive layer, and landscape position would be useful when slopes and soils are uniform throughout the watershed. The evaluation identified possible misinterpretations of vulnerability for cropland artificially drained with surface ditches. The appeal of the SVI is its simplicity and readily available source data, yet rain amount and intensity are known to impact runoff and leaching but are not included in the classification. The SVI leverages the huge investment NRCS has made in the Soil Survey Geographic Database (SSURGO), for purposes possibly beyond those originally envisioned for conservation planning. Planners and conservation managers can combine SVI with information about practices implemented in an area to assess further conservation needs. This evaluation, which highlighted the strengths and limitations of SVI, alerts planners of when they can have confidence in or should be careful with the results.
3. A precision agriculture system including no-till, cover crops and precision-applied inputs mitigated the negative effects of no-till alone on soils with a restrictive layer. Short-term monitoring studies have shown that, in the context of claypan soils, no-till cropping systems reduce sediment losses but do not reduce runoff compared to mulch-tilled systems. Consequently, no-till can double or triple the transport of non-incorporated chemicals, such as herbicides and dissolved phosphorus. Questions remained regarding the effects of no-till in combination with other conservation practices. ARS scientists in Columbia, Missouri, along with University of Missouri cooperators, used long-term crop yield and water quality data to compare the effects of a precision agriculture system (PAS) that combined no-till, cover crops, a longer rotation, and precision-applied inputs to those of a minimum-till two-year rotation. Soil loss from the PAS decreased by 85% and nitrogen losses in surface runoff decreased by 40%. The PAS maintained crop yields obtained with the minimum-till system and mitigated the disadvantages of no-till alone for the transport of herbicides and dissolved phosphorus. These conclusions (reduction of soil loss and nitrogen in surface runoff, but similarity of all other environmental and production performance measures compared to tilled systems) are useful to producers and conservation managers who consider no-till systems combined with cover crops and precision nutrient management on claypan soils and provide them realistic expectations regarding production benefits. These conclusions will also guide research needs to improve the overall sustainability of cropping systems.
4. In watersheds dominated by claypan soils, nitrates move through the claypan via preferential flow and herbicides move with interflow. Nutrients and herbicides stream loads are significant concerns in the Central Claypan Region of northeastern Missouri, where restrictive layer (claypan) soils are dominant. Thus, there is a need for better understanding of watershed-scale processes that control contaminant transport in this region. ARS scientists in Columbia, Missouri, along with Lincoln University cooperators used geochemical tracers to determine the major hydrologic pathways responsible for generating streamflow in Goodwater Creek, Missouri. Results showed that streamflow in Goodwater Creek was dominated by surface runoff, which accounted for 59% of the flow, followed by interflow (25% of flow) and groundwater (16% of flow). Despite their poor drainage, claypan soil watersheds have significant nitrate contamination of groundwater, and the results showed it to be the primary source of nitrate in the stream. The study also provided strong evidence that interflow, contaminated with high herbicide levels, is the cause for the prolonged high levels in the stream. Findings of this study will be used to improve existing computer simulation models used to predict movement of contaminants in fields and watersheds with restrictive layer soils.
5. Land use changes may mitigate the effects of climate change on stream flow, thus ensuring future water availability. Planning for and adaptation to future shortages or excesses of municipal and agricultural water requires an understanding of how temperature, precipitation, and stream flow may change in response to climate. ARS scientists in Columbia, Missouri, and University of Missouri cooperators obtained climate data from multiple climate datasets and used them to drive computer simulation models and simulate future infiltration, evaporation, plant growth and stream flow in the 2,300 square mile Mark Twain Lake watershed, in Missouri. Results indicated increased temperatures and annual precipitation, along with a decrease in summer precipitation, a critical factor for crop growth. Scheduling of spring field work may be more challenging because of wet soils that make operation of large equipment difficult. Combined climate and land use change scenarios showed that doubling forest coverage by converting crop and pasture land has the potential to mitigate the effects of climate change on stream flow, thus ensuring future water availability. These scenario analyses inform water resource managers of what may happen during the next 20 -100 years and how they might address the challenges.
6. Methods for partitioning deisopropylatrazine in streams. Streams within the Salt River Basin of northeastern Missouri, are chronically contaminated with atrazine, simazine, and their common metabolite, deisopropylatrazine (DIA). Both triazine herbicides can degrade to form DIA. However, in order to link stream pesticide amounts to herbicides applied in the fields, one needs to know the parent source of DIA. Therefore, a method is needed to partition DIA between its two parent sources – i.e., DIA derived from atrazine (DIAATR) and that from simazine (DIASIM). ARS scientists in Columbia, Missouri, along with University of Missouri cooperators, developed a method based on the concentration ratios of simazine to atrazine (SAR) in streams. They showed that the method performed better than two methods based on concentrations of chloro-triazines in field runoff. The SAR method results demonstrated the differences in DIASIM and DIAATR transport timing, with peak DIASIM transport occurring from mid-November to April and peak DIAATR transport from May to June. In the Salt River Basin, dual season triazine applications substantially increased the period of high chloro-triazine concentrations in streams from approximately three to eight months per year. This new method provides water resources and conservation managers the means to identify the parent herbicide and target conservation efforts toward its management in order to improve water quality.
7. Dicamba formulation did not affect air concentrations after application but atmospheric conditions did. Since 2017, use of commercial products containing glyphosate and dicamba has resulted in an unprecedented number of dicamba drift-related injury cases, mainly to soybean, in the United States. ARS scientists in Columbia, Missouri, along with University of Missouri cooperators, studied the movement of dicamba applied to soybean under field conditions in central Missouri to determine air concentrations of dicamba following application of two commercially available formulations designed to reduce drift. Results showed that dicamba concentrations were highest in the first eight hours following application, and it was detectable in air samples up to 72 hours after application. Dicamba formulation had no significant effect on air concentrations. Dicamba concentrations were greatest under stable atmospheric conditions when temperature inversions develop in later afternoon to early evening. These field-level data show that new commercial dicamba formulations can volatilize over time and that atmospheric conditions at application greatly affect dicamba concentrations in air. These results inform pesticide regulators and pesticide users on Dicamba air concentrations after application and factors that may reduce exposure to this pesticide.
Lui, F., Lerch, R.N., Yang, J., Peters, G. 2020. Determining hydrologic pathways of streamflow using geochemical tracers in a claypan watershed. Hydrological Processes. 34(11):2494-2509. https://doi.org/10.1002/hyp.13743.
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Lohani, S., Baffaut, C., Thompson, A.L., Aryal, N., Bingner, R.L., Bjorneberg, D.L., Bosch, D.D., Bryant, R.B., Buda, A.R., Dabney, S.M., Davis, A.R., Duriancik, L.F., James, D.E., King, K.W., Kleinman, P.J., Locke, M.A., McCarty, G.W., Pease, L.A., Reba, M.L., Smith, D.R., Tomer, M.D., Veith, T.L., Williams, M.R., Yasarer, L.M. 2020. Performance of the Soil Vulnerability Index with respect to slope, digital elevation model resolution, and hydrologic soil group. Journal of Soil and Water Conservation. 75(1):12-27. https://doi.org/10.2489/jswc.75.1.12.
Thompson, A.L., Baffaut, C., Lohani, S., Duriancik, L., Norfleet, L., Ingram, K. 2020. Purpose, development, and synthesis of the Soil Vulnerability Index for inherent vulnerability classification of cropland soils. Journal of Soil and Water Conservation. 75(1):1-11. https://doi.org/10.2489/jswc.75.1.1.
Bish, M.D., Farrell, S.T., Lerch, R.N., Bradley, K.W. 2019. Dicamba losses to air after applications to soybean under stable and nonstable atmospheric conditions. Journal of Environmental Quality. 48(6):1675-1682. https://doi.org/10.2134/jeq2019.05.0197.
Baffaut, C., Thompson, A.L., Duriancik, L.F., Ingram, K.A., Norfleet, M. 2020. Assessing cultivated cropland inherent vulnerability to sediment and nutrient losses with the Soil Vulnerability Index. Journal of Soil and Water Conservation. 75(1):20A-22A. https://doi.org/10.2489/jswc.75.1.20A.
Baffaut, C., Ghidey, F., Lerch, R.N., Veum, K.S., Sadler, E.J., Sudduth, K.A., Kitchen, N.R. 2020. Effects of combined conservation practices on soil and water quality in the Central Mississippi River Basin. Journal of Soil and Water Conservation. 75(3):340-351. https://doi.org/10.2489/jswc.75.3.340.
Lerch, R.N., Willett, C.D. 2019. Chloro-triazine transport to streams - evaluating methods for partitioning deisopropylatrazine sources. Science of the Total Environment. 697:133931. https://doi.org/10.1016/j.scitotenv.2019.133931.
Lohani, S., Baffaut, C., Thompson, A.L., Sadler, E.J. 2020. Soil Vulnerability Index assessment as a tool to explain annual constituent loads in a nested watershed. Journal of Soil and Water Conservation. 75(1):42-52. https://doi.org/10.2489/jswc.75.1.42.
Phung, Q., Thompson, A., Baffaut, C., Costello, C., Sadler, E.J., Svoma, B., Lupo, A., Gautam, S. 2019. Climate and land use effects on hydrologic processes in a primarily rain-fed, agricultural watershed. Journal of the American Water Resources Association. 55(5):1196-1215. https://doi.org/10.1111/1752-1688.12764.
Yasarer, L.M., Lohani, S., Bingner, R.L., Locke, M.A., Baffaut, C., Thompson, A.L. 2019. Assessment of the Soil Vulnerability Index and comparison with AnnAGNPS in two Lower Mississippi River Basin watersheds. Journal of Soil and Water Conservation. 75(1):53-61. https://doi.org/10.2489/jswc.75.1.53.
Baffaut, C., Baker, J.M., Biederman, J.A., Bosch, D.D., Brooks, E.S., Buda, A.R., Demaria, E.M., Elias, E.H., Flerchinger, G.N., Goodrich, D.C., Hamilton, S.K., Hardegree, S.P., Harmel, R.D., Hoover, D.L., King, K.W., Kleinman, P.J., Liebig, M.A., McCarty, G.W., Moglen, G.E., Moorman, T.B., Moriasi, D.N., Okalebo, J., Pierson Jr, F.B., Russell, E.S., Saliendra, N.Z., Saha, A.K., Smith, D.R., Yasarer, L.M. 2020. Comparative analysis of water budgets across the U.S. long-term agroecosystem research network. Journal of Hydrology. 588. https://doi.org/10.1016/j.jhydrol.2020.125021.