Location: Cropping Systems and Water Quality Research
2021 Annual Report
Objectives
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.
Approach
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.
Progress Report
Obj.1a. The use of Agricultural Policy/Environmental eXtender (APEX) results required the adaptation of the models developed with APEX0806 for the plots to APEX1501. This adaptation is near completion.
Obj. 1b. The site and equipment inspection required prior to a restart of the sediment and nutrient loading assessment at three ditch sites in the Little River Drainage Ditches showed that the equipment had been severely damaged due to weather and in one case destroyed. In addition, the largest ditch is being cleaned so the old calibration will not apply. These circumstances would cause incompatibility of new data with previously collected data and require a complete restart of the project. Since it is the end of the current project plan cycle, it was deemed not worth doing this.
Obj. 1c. The glyphosate and dissolved phosphorus and ammonium analyses from the northern Missouri/southern Iowa Region streams were recently completed. A backlog on the total phosphorus and nitrogen and dissolved nitrogen analyses remains.
Obj. 2a. Data collection on the effect of grasses and vegetative buffers on the fate and transport of organic contaminants, veterinary antibiotics, and estrogen is completed. Despite observing degradation of atrazine by switchgrass phytochemicals in laboratory assays, we failed to identify the phytochemicals in switchgrass buffers. A manuscript is under development.
Obj. 2b. Certification of the 2019 and 2020 data that characterize the effectiveness of buffer strips, crop rotations and cover crops is nearly completed. A manuscript on buffer effectiveness is under development.
Obj. 3a and 3b. Monitoring and upkeep of Long-Term Agroecosystem Research (LTAR) observatory and of the cropping systems needed for the Common Experiment 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). Data from the weather station at the Centralia Research Center are now going to the Agricultural Collaborative Research Outcomes System (AgCROS) Server after having gone through Phases 1 and 2 of the quality assurance/quality control (QA/QC) process, which flag inconsistencies with the experimental range of values obtained at these sites. Phases 3 and 4 of QA/QC, which involve visual inspection, comparison with data from nearby sensors, possible replacement, and approval are ongoing. Flow and water quality monitoring are on-going for both fields and two out of three replicates of the large plots. Water quality analyses of water samples are completed up to August 2018 and the backlog is being progressively addressed. Flow data for 2019 and 2020 are proceeding through QA/QC per established procedures. Flow data and samples from 2021 are being collected. Eddy flux measurements are ongoing on both fields and data processing is progressing with help from our cooperators. One of the eddy flux towers is now registered within the Ameriflux network, the Department of Energy supported network of sites measuring ecosystem carbon, water, and energy fluxes in North, Central and South America.
The Aspirational (ASP) cropping system was initiated in 2015 in one field, nine large (18 m x 180 m) replicated plots at the Centralia Research Center, and 16 small (6 m x 9 m) plots referred to as the Soil Productivity Assessment for Renewable Energy and Conservation (SPARC) research plots. The basic ASP rotation started as a corn-soybean-wheat rotation. Aspirational aspects of the treatment include the 3-year rotation, cover crops at any time a grain crop is not planted, no tillage, and a precision agriculture nutrient management system. The Business-as-usual (BAU) scenario started in 2016 in another field near Centralia and on the two sets of plots. In 2019, the protocol called for corn in the ASP field, but excessive spring rainfall made corn planting impossible during the recommended planting window. The research team decided to plant soybean and revise the cropping system to a 4-year ASP rotation that includes perennial grasses. Hay has been harvested twice using yield mapping technologies.
Given the longer duration of the rotation, representing each phase of the rotation was not possible on the nine large plots dedicated to ASP. Therefore, we maintained the original ASP system on three plots, implemented the current ASP system on three plots, and are experimenting with replacing corn in the original ASP rotation with sorghum on the three remaining plots. Meanwhile, the operations of the BAU scenario defined by a producer on a different field (i.e., crop selection, field operation type and timing, fertilizer rate) continue to be implemented on replicated plots.
Crop yields from FY19 and FY20 are complete and certified. Aboveground net primary productivity and plant tissue chemistry samples from FY19 and FY20 have been collected and processing is ongoing. FY20 soil samples have been collected for ongoing measurements of microbial abundance, diversity, and function. Crop phenology images are transmitted automatically to the PhenoCam Network, a network of sites equipped with cameras that provide automated sensing of phenology (nature’s calendar, as described by plant emergence or plant maturity for example). Our biologist collaborator is collecting plant diversity data and collaborating with the LTAR Archbold Biological Station-University of Florida (ABS-UF) site.
Obj. 3c. Greenhouse gas measurements, along with soil moisture, oxygen, and temperature data were set up at 19 SPARC plots. It took several years to get the field equipment and gas chromatograph operational and a complete and valid weekly greenhouse gas (GHG) data set was obtained for the BAU and ASP plots during the FY19 growing season. GHG measurements were interrupted in 2020. Given that the dataset is only one-year long and does not include high quality data that characterize GHG emissions following rainfall events, the dataset is insufficient for drawing any conclusion.
Obj. 3d. Data collection for assessing denitrification in claypan soils is completed. Two manuscripts are under development: 1) spatial distribution and landscape dependence of potential and actual denitrification from BAU and ASP fields; 2) assessment of RNA-based methods for quantifying denitrification. The field-scale estimates of denitrification for BAU and ASP fields are completed but are not publishable without comparison to an existing denitrification model. A multi-site denitrification paper with results from LTAR sites in Pennsylvania, Georgia, and Missouri has been published.
Obj. 3e. The work implemented to assess water availability and productivity in the Goodwater Creek Experimental and Mark Twain Lake watersheds under varying climate (Obj. 3e) is complete. The manuscript on the prediction of future drought risk in the region is published. A fourth manuscript on the balance between future water demand and availability was submitted and revised. A book chapter on the modeling approach to address soil water management under climate change has been submitted.
Accomplishments
1. Nitrous oxide emission from agricultural soils may be very low compared to nitrogen gas emissions. Although much attention has been given to the potential for agricultural soils to store carbon, the 100-year global warming potential (GWP) of nitrous oxide (N2O) is 265-298 times higher than carbon dioxide. Scientists at the City University of New York working in collaboration with ARS scientists at the Columbia, Missouri, Tifton, Georgia, and University Park, Pennsylvania LTAR network sites measured potential soil denitrification rates by directly measuring dinitrogen (N2) and N2O production in grams per hectare per day that ranged from 46-783 at the Pennsylvania site, 227-763 at the Missouri site, and 1246-1448 at the Georgia site. Of these totals, conversion to nitrogen gas (N2), which has no GWP, was consistently greater than 90% of the denitrification product, indicating that less than 10 % of denitrification contributed to N2O emissions. Observations suggested that denitrification can be significant at low topographic positions, in the presence of soil layers that trap water, and during soil rewetting after dry periods. These findings will be important for producers and resource conservation specialists when developing strategies to manage nitrogen (N) for soil fertility, water quality, and reduced N2O emissions.
2. On claypan soils, spring droughts may become more frequent in the future. Although earth system models predict future precipitation and temperature, prediction of stream flows and soil moisture may be more relevant for agriculture. Scientists at the University of Missouri, in collaboration with ARS researchers at Columbia, Missouri, have simulated discharge and soil moisture in the Goodwater Creek Experimental Watershed (the observatory watershed of the Missouri Long-Term Agroecosystem Research site) using future precipitation and temperature predicted by global climate models. The results indicated both a decline in summer precipitation and, as expected, more frequent and longer summer droughts based on precipitation, stream flow, and soil moisture. However, despite a predicted increase in future spring precipitation, the results showed more frequent spring periods with low stream flow and soil moisture because future rain events will not be well distributed during the spring season and the soils in this region have low infiltration and a low water storage capacity. This research helps agriculture and natural resource managers plan for and adapt to a changing climate and decide what further analyses are necessary.
3. A regional framework for the USDA Long-Term Agroecosystem Research (LTAR) network characterizes the network and identifies gaps. The USDA LTAR network, a partnership of 18 U.S. sites that conducts agroecosystem research at plot, field/pasture, enterprise, and watershed levels needed a coherent spatial framework to assign specific regions to each individual site and enable cross-site, cross-scale, regional and network-level synthesis of agricultural research. ARS researchers at Tifton, Georgia, Tucson, Arizona, Venus, Florida, Oxford, Mississippi, Columbia, Missouri, and University Park, Pennsylvania, in collaboration with scientists from the University of Arizona, led a task force to identify regional areas for each of the 18 LTAR sites within three domains (production of food, fuel and fiber; environmental impacts; and rural prosperity). Three indicators selected for their availability in national databases (land use for production, agricultural nitrogen runoff for environmental impacts; and farm income for rural prosperity) provided a preliminary characterization of the LTAR network. The “production regional areas” layer has been adopted by the LTAR network and is now used for various tasks, from enhancing the allocation of LTAR network level resources and the identification of stakeholders, to the identification of gaps (California agricultural area) in the network. In the future, this framework will be refined using additional indicators selected for their relevance to the estimation of the effects across broad areas resulting from adoption of new, transformative approaches to agricultural production.
4. Long-term research in ARS experimental watersheds has had societal benefits outside of the agricultural domain. The visionary investments in building and maintaining the USDA-Agricultural Research Service network of experimental watersheds and associated scientific investigations for more than half a century have not only resulted in numerous and documented high impact research accomplishments but also a wide array of less documented accomplishments that directly benefit society. ARS researchers in Tucson, Arizona, Boise, Idaho, Tifton, Georgia, Beltsville, Maryland, Oxford, Mississippi, Columbia, Missouri, El Reno, Oklahoma, University Park, Pennsylvania, and collaborators at Kansas State University have identified and, in some instances, quantified direct and indirect societal benefits. Development of conservation tillage practices has decreased erosion on U.S. cropland by 43%, thus contributing to healthier soils, and preventing close to 0.7 billion tons of soil from entering waterbodies. Billions of dollars of infrastructure investment and methods to size bridges, culverts, and drainage infrastructure have been guided by models developed from watershed observations and derived process knowledge. In some instances, ARS models were used outside the agricultural domain to guide the cleanup of soils at nuclear laboratory sites savings billions. The ARS Experimental Watersheds formed the core of the recently established Long-Term Agroecosystem Research (LTAR) Network. LTAR will expand the mission of the ARS Watershed network to include agricultural intensification without ecosystem degradation while enhancing rural prosperity.
Review Publications
Beringer, C.J., Goyne, K.W., Lerch, R.N., Webb, E.B., Mengel, D. 2021. Clothianidin decomposition in Missouri wetland soils. Journal of Environmental Quality. 50(1):241-251. https://doi.org/10.1002/jeq2.20175.
Conway, L.S., Yost, M.A., Kitchen, N.R., Sudduth, K.A., Massey, R.E., Sadler, E.J. 2020. Cropping system and landscape characteristics influence long-term grain crop profitability. Agrosystems, Geosciences & Environment. 3(1). Article e20099. https://doi.org/10.1002/agg2.20099.
Vong, C., Conway, L.S., Zhou, J., Kitchen, N.R., Sudduth, K.A. 2021. Early corn stand count of different cropping systems using UAV-imagery and deep learning. Computers and Electronics in Agriculture. 186. Article 106214. https://doi.org/10.1016/j.compag.2021.106214.
Weitzman, J.N., Groffman, P.M., Adler, P.R., Dell, C.J., Johnson, F.E., Lerch, R.N., Strickland, T.C. 2021. Drivers of hot spots and hot moments of denitrification in agricultural systems. Journal of Geophysical Research-Biogeosciences. 126(7). Article e2020JG006234. https://doi.org/10.1029/2020JG006234.
Gautam, S., Costello, C., Baffaut, C., Thompson, A., Sadler, E.J. 2021. Projection of future drought and extreme events occurrence in Goodwater Creek Experimental Watershed, Midwestern US. Hydrological Sciences Journal. 66(6):1045-1058. https://doi.org/10.1080/02626667.2021.1906878.
Goodrich, D.C., Heilman, P., Anderson, M.C., Baffaut, C., Bonta, J.V., Bosch, D.D., Bryant, R.B., Cosh, M.H., Endale, D.M., Veith, T.L., Havens, S.C., Hedrick, A., Kleinman, P.J., Langendoen, E.J., Mccarty, G.W., Moorman, T.B., Marks, D.G., Pierson Jr, F.B., Rigby Jr, J.R., Schomberg, H.H., Starks, P.J., Steiner, J., Strickland, T.C., Tsegaye, T.D. 2020. The USDA-ARS experimental watershed network – Evolution, lessons learned, societal benefits, and moving forward. Water Resources Research. 57(2). Article e2019WR026473. https://doi.org/10.1029/2019WR026473.
Bean, A.R., Coffin, A.W., Arthur, D.K., Baffaut, C., Holifield Collins, C.D., Goslee, S.C., Ponce Campos, G.E., Sclater, V., Strickland, T.C., Yasarer, L.M. 2021. Regional frameworks for the USDA Long-Term Agroecosystem research (LTAR) Network: Preliminary concepts and potential indicators. Frontiers in Sustainable Food Systems. 4:612785. https://doi.org/10.3389/fsufs.2020.612785.
