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ARS Home » Southeast Area » Tifton, Georgia » Southeast Watershed Research » Research » Research Project #441611

Research Project: Shifting the Balance of Water Resources and Interacting Agroecosystem Services Toward Sustainable Outcomes in Watersheds of the Southern Coastal Plain

Location: Southeast Watershed Research

Project Number: 6048-13000-028-000-D
Project Type: In-House Appropriated

Start Date: Feb 7, 2022
End Date: Feb 6, 2027

1. Quantify and assess the patterns, trends, and interactions among agroecosystems and landscape components and their impacts on water supply and water quality within the Little River Experimental Watershed (LREW) and in agricultural watersheds of the southeastern U.S. 1.A. Quantify the differences between water use and storage capacity among differing land use types in agricultural watersheds of the Georgia Coastal Plain. 1.B. Quantify differences in water quality as a function of land use in LREW sub-watersheds. 2. As part of the Long-Term Agroecosystem Research (LTAR) Network and a participant in the Conservation Effect Assessment Project (CEAP) effort, use GACP and other LTAR sites to quantify contrasting agroecosystem responses to “Business-As-Usual” and “Aspirational” treatments, among others, at plot, field, and farm scales. 2.A. Quantify the plot-level biophysical and hydrological responses to ASP practices as compared with BAU, that are characteristic of the GACP LTAR Network site. 2.B. Characterize and quantify the contaminants and dissolved trace gases transported from agroecosystems by surface and subsurface flow. 3. Quantitatively assess the effects of agricultural conservation practices on ecosystem services at field, landscape, and regional scales in agricultural watersheds of the southeastern US. 3.A. Characterize field level spatial and temporal variability of biophysical parameters on three farms within the LREW. 3.B. Quantify meteorological and phenological characteristics from crops under differing management practices. 4. Utilize landscape and watershed scale assessment models to improve understanding of tradeoffs among ecosystem services and evaluate the long-term sustainability of agricultural watersheds. 4.A. Estimate ecosystem services provided by GACP agricultural landscapes. 4.B. Quantify the impacts of regional cropping patterns, conservation practices and winter covers on hydrology and water quality in GACP watersheds. 4.C. Evaluate uncertainties in the regional water balance and scenarios of long-term water quality as a response to intensifying seasonal climatic extremes. 4.D. Evaluate tradeoffs in ecosystem services related to scenarios of conservation practice implementation for enhancing long-term sustainability of agricultural watersheds in the GACP region.

The goal of this project is to leverage our knowledge about the tradeoffs in ecosystem services to support stakeholder decisions about the balance of costs and benefits of conservation practice implementation. An additional goal includes contributions to the LTAR Network’s Strategic Plan by considering agroecosystem responses to sustainable intensification strategies. We do so by accounting for uncertainties in the regional water balance due to intensifying seasonal climatic extremes in order to more effectively manage ecosystem services through proper placement of conservation practices in the landscape. The proposed research uses plot, field, landscape, and watershed observations from multiple locations in the 334 km2 Little River Experimental Watershed (LREW; centered at N31°36', W83°37') that are the basis for our long-term hydrology and natural resources research at SEWRL. Experiments are designed to evaluate processes at plot-to-landscape levels using the LREW as the basis for validating modeled outcomes from practice implementation. Each objective and sub-objective is designed to address selected spatial and temporal processes, provide information for extrapolations across scales, and/or explore novel technical approaches for characterizing ecosystems services within the LREW. Research is conducted on large plots (0.08 – 0.12 ha) at several farms in partnership with the University of Georgia, private producers’ fields (50 – 72 ha) within the LREW, and multiple collaborators. We will compare historical observations in flow, ET, land cover, and groundwater withdrawal practices to better understand trends in the watershed. We will compare annual and seasonal means of discharge using appropriate parametric and non-parametric tests for analysis of watershed data. Rates of ET will be compared where quantifiable. Geospatial statistics and simulation models offer innovative methods for quantifying the relationships between land-use change, its driving factors and downstream effects on hydrology, nutrient loading, dissolved organic carbon chemistries, and effects of agricultural versus urban associations with water quality. As part of the LTAR Network, aspirational cropping scenarios that include biofuel feedstock production and winter cover crops will be compared to traditional (business-as-usual) systems with respect to impacts on ecosystem services (primarily C and nutrient stocks, water holding capacity, and stream flow and water quality), and profitability for producers. A long-term approach is necessary to fully evaluate the potential magnitudes of change as well as the stability of these changes. A combined approach using remote sensing and physical sampling will be used to measure changes to vegetation and crop production in relation to soil and weather conditions as affected by management practices. Regular image collection using multispectral UAS-borne sensors will occur throughout the year with flights timed to capture phenological stages in crop development. Inferences between the implemented conservation practices and the hydrologic and water quality impacts will be assessed via modeling.