Location: Cropping Systems and Water Quality Research
2017 Annual Report
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:
The work conducted in 2017 has focused on transitioning from our previous project (5070-12130-005-00D) to this one. On one hand, we have finalized research conducted under the previous project. Results show that APEX can be used to generate runoff values for the purpose of testing P Index under varying conditions but caution is necessary when generating soil and phosphorus loss values without first calibrating the model (Obj 1). As part of this work, we have identified limitations of APEX to simulate upland buffers (Obj 2b) and have proposed new algorithms that have been incorporated in the official APEX version. The site-specific management system has been evaluated for productivity (Yost et al., 2017) and the profitability manuscript comparing these same two systems is nearly complete (Obj. 3b). These analyses and publications provide a baseline for LTAR investigations.
On the other hand, new research infrastructure has been established to support LTAR, the comparison of the BAU and ASP management scenarios, and long-term management of water resources in the region. A reference flux tower in a remnant prairie site has been negotiated with the oversight committee, the specific site has been chosen, the flux station has been designed, and steps are underway to establish the equipment (Obj 3b). Studies to screen for atrazine degrading compounds in eight switchgrass varieties were initiated (Obj. 2a). The large plots that had been unsuccessful for bioenergy willow trees and miscanthus in 2015 and 2016 were repurposed to follow the BAU management for the benefit of the LTAR common experiment. Data are being successfully collected on BAU and ASP research fields and replicated large and small plots in support of LTAR:
• The telemetry system for automated data collection, storage, and remote access is expanding. Soil sensors mentioned above, weather data at the small plots, discharge data from the large plots were FY17 additions to the network. Automated data collection has enabled automated QA/QC, rapid problem diagnosis and resolution, and is expected to improve the overall quality of the data. Certification of FY15 and FY16 data is expected to be complete by the end of FY17 (Obj 3a).
• Soil cores were collected from the BAU and ASP fields and large plots for soil characterization and bio-diversity measurements (Obj. 3b).
• Greenhouse gases sampling and analysis (Obj 3c) has started on 18 small plots, with >2,000 samples collected in FY17.
• The denitrification study has started with soil cores collected from ASP and BAU fields and sent to a cooperator to measure denitrification using a soil incubation chamber (Obj. 3d). Six sets of soil sensors to monitor soil oxygen, temperature, and water content were deployed at 10 and 20 cm depths in the BAU and ASP field sites.
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) has progressed. Downscaled and bias corrected Global Climate Models (GCM) weather data (temperature and precipitation) from 12 GCM and 2 emission scenarios were used as inputs for SWAT models of the two watersheds. Ensemble results show that annual water yield and surface runoff are predicted to increase in both the near and far future along with an increase in frequency and duration of droughts, compared to the historical 1970-2010 period.
Work under the NACA implemented to evaluate and improve the NRCS Soil Vulnerability Index has progressed to near completion. Ten reports have been written, one for each of 10 watersheds. The results highlight that soil vulnerability index (SVI) can be useful for cropland with low and moderate slopes but tends to over-estimate the risk of sediment and nutrient transport by runoff when there is drainage. Leaching risk can be under-estimated for soils with dual hydrologic group for drained and undrained conditions. Finally, the index is not very useful for watersheds with steep slopes. Several suggestions are proposed to improve the index.
4. Accomplishments
1. New tools to detect degraded sensors. Automated weather stations and other installations require substantial labor for care and maintenance to ensure high quality data are collected. Some installations use a second sensor to provide a check on the primary one. Even so, it is difficult to detect the onset of sensor problems that although small, degrade the quality of the data products. Using datalogger and post-processing approaches (i.e., no additional equipment), ARS researchers and cooperators at Columbia, Missouri, produced tools that inform the quality assurance process for both single- and dual-sensor installations. Implementing these tools can assist researchers in producing higher-quality weather and other sensor-based data for use in empirical and model-based research to solve agricultural problems.
2. A regional parameter set for the Agricultural and Policy Environmental Extender (APEX). APEX is capable of estimating edge-of-field water, nutrient, and sediment transport and is used to assess the environmental impacts of agricultural management practices. The program requires hundreds of input parameters, some of which need to be adjusted (i.e., calibrated) based on the comparison of simulated flow and water quality. Since flow and water quality data are not always available measured data, ARS researchers in Columbia, Missouri and university cooperators developed and validated a regionally calibrated model using data from twelve sites with restricted-layer soils of Iowa, Missouri, and Kansas. Use of APEX with this parameter set can produce very good estimates of event runoff but total phosphorus loss estimates should be used with caution due to poor simulation of sediment loss. Availability of this parameterization strategy is important for researchers and water resource managers who need runoff estimates on soils with restrictive layers but do not have the data or resources to calibrate the model.
3. Computer simulation models should be calibrated with data from several management systems. Computer simulation models are being used to evaluate the effects of management practices on water quality. For this purpose, they are often calibrated (i.e., input parameters are adjusted so that simulated results match monitoring data) with data specific to one management practice, and then used to evaluate alternative management systems. ARS researchers in Columbia, Missouri and university cooperators calibrated the APEX model and tested its accuracy with the management used for calibration and with different managements. Models were also developed by using data from all the managements together. When applied outside the calibration management, the models were accurate only in 1/3 of the tests. Models developed with data from multiple managements were more accurate. For maximum confidence, models should only be applied within the managements used for calibration. Using data from multiple management systems for model calibration should increase result reliability. These results are important model limitations that researchers and water resource managers need to be aware of for improved confidence in model results.
4. Vegetative buffer strips reduce herbicides in runoff. Vegetative buffer strips have been shown to be effective for reducing sediment and nutrient transport from fields, but they had not been tested for reducing herbicides from high runoff potential soils. This study evaluated the effects of different grasses, buffer width, and season on the movement of three commonly used herbicides - atrazine, metolachlor, and glyphosate– in runoff from a claypan soil. All grass treatments were shown to be similarly effective at reducing herbicide and sediment losses in runoff, and reductions in contaminant load were mainly related to buffer width. Using equations developed from this study, herbicide load reductions can be estimated for any combination of source drainage area and buffer width. These models provide conservation agencies and landowners a simple tool for effectively implementing buffer strips to control herbicide losses from cropped fields.
Baffaut, C., Nelson, N.O., Lory, J.A., Senaviratne, G., Bhandari, A.B., Udawatta, R.P., Sweeney, D.W., Helmers, M.J., Van Liew, M.W., Mallarino, A.P., Wortmann, C.S. 2017. Multisite evaluation of APEX for water quality: 1. Best professional judgement parameterization. Journal of Environmental Quality. doi: 10.2134/jeq2016.06.0226.Bhandari, A.B., Nelson, N.O., Sweeney, D.W., Baffaut, C., Lory, J.A., Senaviratne, G., Pierzynski, G.M., Janssen, K.A., Barnes, P.L. 2016. Calibration of the APEX model to simulate management practice effects on runoff, sediment, and phosphorus loss. Journal of Environmental Quality. doi: 10.2134/jeq2016.07.0272.
Sadler, E.J., Sudduth, K.A., Drummond, S.T., Thompson, A.L., Chen, J., Nash, P.R. 2016. Inferring random component distributions from environmental measurements for quality assurance. Agricultural and Forest Meteorology. 237:362-370. doi: 10.1016/j.agrformet.2017.02.021.
Lerch, R.N., Lin, C.H., Goyne, K.W., Kremer, R.J., Anderson, S.H. 2017. Vegetative buffer strips for reducing herbicide transport in runoff: effects of buffer width, vegetation, and season. Journal of the American Water Resources Association. 53(3):667-683. doi: 10.1111/1752-1688.12526.
Nelson, N.O., Baffaut, C., Lory, J.A., Senaviratne, G., Bhandari, A.B., Udawatta, R.P., Sweeney, D.W., Helmers, M.J., Van Liew, M.W., Mallarino, A.P., Wortmann, C.S. 2017. Multisite evaluation of APEX for water quality: II. Regional parameterization. Journal of Environmental Quality. 56(5):2663-2674. doi: 10.2134/jeq2016.07.0254.
