1a. Objectives (from AD-416):
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.
1b. Approach (from AD-416):
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.
3. Progress Report:
Finalized studies show that APEX can be used with parameter sets developed from nearby sites with similar eco-hydrological characteristics (soil, weather). This should enable the evaluation of P Indices for fields underlain by a restrictive layer (Obj. 1a). Monitoring in Northeast Missouri to assess trends in herbicide and nutrient concentrations in the streams of the northern Missouri/southern Iowa Region (NMSIR) has started in the spring (Obj. 1c). More than 320 stream samples were collected at pre- and post-plant in FY18. Analyses are underway. Demonstrated the presence of atrazine degrading compounds in eight switchgrass varieties, and there were significant varietal differences in degradation (Obj. 2a). Currently working on identifying the phytochemicals and atrazine degradation product(s). Methods development and validation for analyzing veterinary antibiotics and estrogenic compounds is nearing completion. Once finished, degradation studies will be initiated (Obj. 2a). All the data (soil properties, crop production, discharge, and runoff water quality) from the 1991-2009 plot experiment were synthesized by developing APEX models of each individual plot and comparing the long-term effects of three cropping systems (mulch-till and no-till corn-soybean, and no-till corn-soybean-wheat with cover crops). The analysis showed the environmental superiority of the no-till 3-year rotation with cover crops. A manuscript was developed and submitted (Obj. 2b). Meanwhile, implementation of Long-Term Agroecosystem Research (LTAR) cropping systems and plant, soil, water, and air sampling are ongoing at three scales: small plots SPARC, large plots (Centralia), and fields (Centralia) (Obj. 2b, 3a, 3b). New flow monitoring sensors that will require less maintenance, and thus less technician time, were evaluated to replace the pressure transducers. Made the decision to progressively replace all pressure transducers by these new flow bubblers. Plot monitoring data are undergoing data quality analysis per established protocol. Plot flow data through 2017 and water quality data through 2016 were certified. Plot 2017 water quality data are proceeding through quality analysis. Initial statistical analysis of October 2015 - October 2017 flow data from six cropping systems has started (Obj. 2b). Weather, flow, and water quality data at field and stream sites data through 2016 were uploaded in Sustaining the Earth's Watersheds, Agricultural Research Data System (STEWARDS) by Q1FY2018 per STEWARDS protocol (Obj.3a). Data for 2017 are proceeding through quality analysis per established procedures. Current CMRB weather data are uploaded to NAL on hourly basis. Energy, carbon, and water vapor flux data are available pending post-processing (Obj. 3b). In addition to ASP and BAU flux sites, established a native prairie as a reference site, and arranged with the Missouri Ozarks AmeriFlux (MOFLUX) site as another, forested, reference. Post-processing, including screening, gap identification, gap-filling, and integrating to daily fluxes has required more effort than anticipated. Evaluated the open-source National Ecological Observatory Network (NEON) Eddy4R and the Max Planck Institute REddyProc packages for this purpose. Chose REddyProc because it matched more closely both our internal data workflow and our database structure, and followed procedures and assumptions accepted in the Ameriflux network. Implemented coordinate rotation and the REddyProc post-processing, and now have only a generalized masking of maintenance activities left to do. Expect to have screened, gap-filled, and integrated daily flux data available by end of FY18. Laboratory analyses of soil samples collected in 2016 were completed, including phospholipid fatty acids, enzymology, total protein, nutrients, total carbon and nitrogen, active carbon, and aggregate stability measurements (Obj. 3b). Annual and seasonal biodiversity samples, specifically for phospholipid fatty acid profiles of the soil microbial community, have been collected, processed, prepared, and delivered to ARS scientist in El Reno, Oklahoma, for analysis beginning in 2016. Results have not yet been received. Draft budgets for water, phosphorus, carbon and nitrogen have been completed using measured values where possible and simulated or literature values otherwise. These budgets have been shared with the LTAR network and uploaded to Basecamp. Overtime, as literature values are replaced with measured values, budgets will be updated. For the denitrification study (Obj. 3d), soil sensor data were collected (soil oxygen, temperature, and water content) for a second year at three locations within the BAU and ASP fields. Sensors are deployed in replicate at 10 and 20 cm depths. ARS scientists at Columbia, Missouri, also collected and shipped soil cores from the BAU field to the Cary Institute to measure denitrification using the soil incubation chamber. Cores were not collected from ASP field as conditions were too dry following wheat harvest. Regardless, this was the fifth set of cores sent for analyses and ARS scientists at Columbia, Missouri, hope to receive data (N flux) from the earlier cores in FY19. Work under the Non-Assistance Cooperative Agreement (NACA) implemented to assess water availability and productivity in the Goodwater Creek Experimental and Mark Twain Lake watersheds under varying climate (Obj. 3e) is near completion. The work on water availability in Goodwater Creek was published. A manuscript was drafted for the work in Mark Twain Lake watershed. Additional work at watershed scale assessed drought risks in Goodwater Creek. Finally, field scale simulations were completed comparing how BAU and ASP management scenarios would fare under assumptions of climate change, and a draft manuscript is underway. Work under the NACA implemented to evaluate and improve the Natural Resources Conservation Service (NRCS) Soil Vulnerability Index (SVI) is near completion. Two sites were added in FY18 to the 11 existing sites: Riesel watersheds in Texas and the Upper Snake Rock watershed in Idaho. Several manuscripts were developed with distinct evaluation foci: (1) the effect of slope and hydrological soil group on SVI and its usefulness as a tool used for evaluating the risks of sediment and nutrient loss at field, watershed and/or regional scale; (2) the purpose, scope, and development of SVI; (3) the effect of drainage in SVI assessment; (4) SVI capacity explain stream sediment and nutrient loads; and (5) how SVI vulnerability assessment compares to sediment and nutrient losses predicted with a hydrologic model. A evaluation of SVI against nitrogen loss from cropland in two adjacent sub-watersheds with contrasting soil characteristics within the Choptank River watershed in the Chesapeake Bay Watershed was published in FY18.
1. Soil sorption of neonicotinoid insecticide affected by land cover. Recent studies indicate that neonicotinoids are harmful to pollinating insects and insect-eating birds, but little is known about the fate of these insecticides in the soil environment. ARS researchers in Columbia, Missouri, evaluated the binding and leaching of the neonicotinoid, imidacloprid, in soils collected at six sites in northern Missouri representing cropland, grass buffer strips, and riparian zones. Results showed that binding of imidacloprid was strongly related to soil organic matter content, with binding strength in the order: riparian zone > grass buffer > cropland. Conversely, imidacloprid leached to the greatest extent through cropland soils. Greater binding and less leaching in the grass buffer and riparian zone soils suggested that these land covers, when located adjacent to cropped fields, could mitigate imidacloprid loss from cropland. Land managers and producers will benefit from this research as it clearly demonstrated that grass buffers and multi-species riparian areas can reduce the movement and ecological impacts of imidacloprid.
2. APEX simulates the effects of buffers on runoff and phosphorus loss. Collecting flow and water quality data to quantify buffer effectiveness for reducing contaminant transport from agricultural fields is time consuming and expensive. Computer simulation models offer alternatives but verification that these models correctly simulate the effects of buffers is needed. ARS scientists at Columbia, Missouri, and University of Missouri collaborators compared model results from the Agricultural Policy Environmental Extender (APEX) to observed data to evaluate the model accuracy. The study utilized 16 years of monitoring data (1991-2009) from three field-scale row crop watersheds. Two watersheds had buffers installed in 1997; the third watershed was maintained as a control. After modifying the model code for improved representation of multiple buffers placed in the landscape, runoff and total phosphorus, and buffer effectiveness were well simulated when the model parameters were determined using the data set collected after buffer implementation. Lack of large sediment loss events caused uncertainties for sediment transport. Scenario analysis indicated that a combination of backslope and footslope agroforestry buffers was more effective than contour placement for reducing runoff and phosphorus losses. The code modification was incorporated into the newest APEX version (APEX1501). These results provide guidance for using APEX to assess upland buffers and for placing buffers in a field for maximum effectiveness.
3. Tools to ensure data quality. Data quality assurance remains a goal of most data management plans, as evidenced by the lack of peer-reviewed, standardized, and general procedures in the literature. Efforts to establish Quality Assurance/Quality Control (QA/QC) procedures are hindered by a lack of tools to identify subtle degradation of data quality, and also by the complexity of conditions that must be considered to detect those changes. Degraded data often show increased variability in addition to the usual missing, out-of-range, constant (stuck), or abruptly changed values. ARS scientists at Columbia, Missouri, developed two procedures to make detection of degraded data more efficient. One procedure detects increased variability from a single sensor or from a dual-sensor station. Another procedure greatly simplifies the code requirements in contrast to if-else methods in common use. Together, these procedures enable more sensitive and more extensive testing of data, and thus could improve quality of environmental data, such as collected at the many thousands of automated weather stations worldwide.
4. Streambanks contribute majority of sediment and phosphorus in streams. Eroding streambanks can be major sources of sediment and nutrients to streams, resulting in property losses and damaged aquatic habitat. ARS scientists in Columbia, Missouri, conducted a four-year study and quantified streambank erosion and its contribution to sediment and phosphorus (P) transport in two watersheds within the Central Claypan Region of northeast Missouri. Streambanks contributed an average of 83% of the stream sediment and accounted for 57% of the total P exported from the two watersheds. These results, along with earlier work showing that streambanks contributed 23% of the total nitrogen exported, clearly demonstrated the impact that bank erosion has on stream water quality. Numerous approaches have been developed for controlling bank erosion, and this study indicated that improved management in flood plains would improve water quality in this region.
5. Future climate is expected to cause increased spring precipitation and surface runoff, and earlier peak evapotranspiration in the Goodwater Creek Experimental Watershed (GCEW). Planning for and adapting to future shortages or excesses of municipal and agricultural water requires an understanding of how temperature, precipitation, stream flow and thus water availability may change in response to climate. Scale of analysis may affect the results. Future projections of temperature and precipitation were used to simulate future stream flow, surface runoff, and transpiration from plants in the 28 square miles GCEW, located in northeast Missouri. ARS scientists in Columbia, Missouri, and university of Missouri cooperators obtained climate data from multiple climate datasets and used them to drive the Agricultural Policy Environmental Extender (APEX) and the Soil and Water Assessment Toll (SWAT) to simulate the above variables. Results indicated increased springtime precipitation, total flow, surface runoff and that evapotranspiration peak would shift one month earlier in the year. Results obtained with models that use soil and land use input data at a coarse resolution showed less impact from future climate than models that use higher resolution inputs. Results show the benefits of impact assessments at small scales with heterogeneous sets of parameters to adequately represent extreme conditions, which are muted by spatial averaging over large domains in global model studies.
6. Atrazine transport in karst terrain. The Pennyroyal Plateau is a karst sinkhole plain in south-central Kentucky with intensive row crop agriculture. Water quality concerns include the transport of agriculture-related herbicides to the groundwater and underground streams via sinkholes. ARS scientists in Columbia, Missouri investigated the movement of a single atrazine application, from a treated field to the water flowing within a cave adjacent to the field. Results showed that atrazine and two of its metabolites were present in every water sample over an 18 month period and levels remained elevated 15 months after application. Transport of atrazine and metabolites to the cave accounted for ~1% of the applied atrazine, losses that were comparable to surface runoff losses in the Corn Belt. A year after application, atrazine and metabolites showed very slow declines in concentration, demonstrating that transport would continue to occur over years and result in consistent, long-term inputs to the deeper groundwater aquifer. This study benefits conservation agencies and growers by demonstrating that importance of atrazine leaching to karst aquifers and raising awareness for the need to implement management practices tailored to karst terrain.
7. The Soil Vulnerability Index (SVI) estimates the risks of organic nitrogen transport better than of nitrate in the upper Choptank watershed. Computer simulation models are valuable tools for identifying areas that contribute most to pollutant loads within agricultural croplands, but their application is limited to locations where data and modeling expertise are available. The USDA Natural Resources and Conservation Service has recently developed a SVI that is based on Soil Survey Geographic (SSURGO) soil properties, which are available for all the U.S., to identify crop fields that have a high risk of pollutant transport through surface runoff and leaching processes. ARS scientists in Columbia, Missouri and Beltsville, Maryland, and University of Maryland cooperators evaluated the suitability of SVI in two adjacent sub-watersheds within the Choptank watershed in Maryland. Outputs from a computer simulation model were used to compare with SVI classification scheme. The SVI method was less suitable for identifying nitrate vulnerability because nitrate transport is mainly caused by leaching. SVI was better suited for organic nitrogen vulnerability because surface runoff is a major pathway for organic nitrogen. These results emphasize the importance of selecting a vulnerable area identification method that is based on the type of pollutant as well as the soil characteristics of the site.
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