Location: Southeast Watershed Research2017 Annual Report
1a. Objectives (from AD-416):
1. Quantify and assess the interactions among agroecosystems and landscape components and their impacts on water supply and water quality in agricultural watersheds of the southeastern U.S. 2. Quantify and assess the effects of agricultural conservation practices and managed land-use interfaces at field, landscape, and watershed scales in agricultural watersheds of the southeastern U.S. 3. As part of the LTAR network, and in concert with similar long-term, land-based research infrastructure in the Gulf Atlantic Coastal Plain (GACP), use the Little River Experimental Watershed (LREW) 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 Gulf Atlantic Coastal Plain (GACP) region. 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. 4. Utilize landscape and watershed scale assessment models to evaluate the long-term sustainability of agricultural watersheds.
1b. Approach (from AD-416):
The research integrates field, landscape, and watershed observations. As such, research sites are located at multiple scales each supporting watershed observations. The SEWRL operates watershed facilities Little River Experimental Watershed (LREW) that are the basis for our long-term hydrology and natural resources research. In addition to these watersheds, the SEWRL has established long-term research at plot (~0.2 Ha) and field (> 10 Ha) scales. The objectives in this plan contribute to the LTAR Common Experiment over-arching hypothesis that “aspirational treatments will increase overall carbon stocks and in particular, soil carbon…leading to increased ecosystem resiliency”. Individual sub-objectives are focused on providing an improved understanding of spatial and temporal drivers and ecosystem services responses associated with the three Common Experiment sub-hypotheses: 1) The magnitude, direction and rate of change will vary with topographic and soil characteristics of the landscape; 2) Sustainable ecosystem productivity, yield, and yield quality will be significantly improved by the development of specific and adaptive G x E x M x Social x Economic systems; and 3) Biologically-based inputs will drive the rate and magnitude of carbon stock increases (e.g., nutrient cycling, insect comminution, decomposition, etc.). The experiments presented are designed as an integrated systems approach to understanding processes at the plot-to-landscape scale using the LREW as the synthesis scale for testing and verification of the Long Term Agroecosystem Research Common Experiment hypothesis. Each objective and sub-objective is designed to address selected spatial and temporal scale processes, provide information for qualifying extrapolations between scales, and/or explore novel technical approaches for characterizing ecosystems services within the LREW. We will use remote sensing, geospatial modeling, statistical modeling and process modeling to evaluate linkages and identify information gaps across scales. Specific research will: 1) characterize the impacts that agricultural land management and land-cover have on water resources in southern coastal plain watersheds; 2) examine relationships between conservation practices (including winter cover), indicators of productivity (e.g. SOC, NPP), other drivers of land cover change, and water quality; 3) characterize composition of DOM with land-use; 4) quantify differences between watersheds with agricultural livestock impacts to watersheds with minimal agricultural livestock impact; 5) quantify stream flow and chemistry differences between urbanized and agricultural watersheds; 6) quantify the impact of agricultural irrigation ponds on watershed water balance; 7) quantify differences in provisioning and regulating ecosystem services between typical and aspirational agricultural production systems; 8) compare spatial and temporal variations between provisioning and regulating ecosystems services; and 9) use landscape and watershed scale assessment models to evaluate the long-term sustainability of agricultural watersheds.
3. Progress Report:
This is a new project which was implemented in February 7, 2017. The first year of this project at intensive plots is dedicated to the sixth year of research begun under the previous NP 211 project. New efforts are just getting started with plot establishment at a second site. Flow data and water quality collection and analysis efforts on the Little River Experimental Watershed (LREW), Gibbs Farm, Tifton Urban Watersheds, and Upper Suwannee River in south Georgia continue (Obj. 1-4). Geographical Information System (GIS) databases of soils, hydrography, and land-cover across the Little River East Watershed (LREW) are being updated. Historical coverages of land-cover are being assembled. Intensive sampling activities continue across private landowner fields in the LREW (Obj. 3). Water samples were collected at sites in the LREW that differ in land-cover to relate molecular-level composition of dissolved organic matter (DOM) to land-use (Obj. 1). Bi-weekly water samples from the LREW, Gibbs Farm and Tifton Urban Watersheds, were analyzed for DOM optical characteristics (started in November 2016). After major rainfall events, water samples from select sites were extracted and the extracts analyzed for DOM molecular-level composition using Gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR) techniques. Method development for the molecular-level analysis of DOM is underway. Existing sites at the dairy farm, LREW O3, and LREW O, along with new sites at the Wilson Farm were used to evaluate livestock impacts at the watershed scale (Obj. 1). Automated flow monitoring and sample collection at existing sites at the dairy farm, LREW O3, and LREW O continues. A cooperative agreement was initiated with our cooperator/owner of the Wilson Farm to allow us access to the farm to initiate installation of hydrologic equipment. For both the dairy farm and Wilson Farm, coordinates at a 90 m grid have been compiled for collecting deep core samples. Sampling at the University of Georgia (UGA) Dairy Farm began in July, 2017. Plot scale research conducted at the University of Georgia Gibbs farm near Tifton, Georgia, obligated under our prior research project, will be completed during the 2017 growing season. The Gibbs farm plots will be re-designed in the fall of 2017 for purposes of this project (Obj. 2, 3). New plots at the University of Georgia Ponder Farm also near Tifton are under development (Obj. 2, 3). As part of this project and our participation in the ARS Long Term Agroecosystem Research (LTAR) network, we have implemented studies to complement ongoing research conducted at all participating LTAR locations (Obj. 3). A completely instrumented meteorological station was installed with near real time data available through the National Agricultural Library (https://ltar.nal.usda.gov/) (Obj. 3). Two stations were established to collect continuous phenological images which are submitted to both the National Agricultural Library site and the phenocam network (http://phenocam.sr.unh.edu/webcam/) (Obj. 3). Two stations also were established to collect continuous eddy-covariance data, a method for quantifying the exchange rates of trace gases over natural ecosystems (Obj. 3). We are utilizing landscape and watershed scale assessment models to evaluate the long-term sustainability of agricultural watersheds (Obj. 4). Toward this goal, a framework for SWAT simulation of the LREW was established. The model was used to quantify the impacts of conservation practices and winter covers in the LREW. A GIS database was designed and geophysical characterization of the watershed is being incorporated into the database.
Liebig, M.A., Herrick, J.E., Archer, D.W., Dobrowolski, J., Duiker, S.W., Franzluebbers, A.J., Hendrickson, J.R., Mitchell, R., Mohamed, A., Russell, J., Strickland, T.C. 2017. Aligning land use with land potential: The role of integrated agriculture. Agricultural and Environmental Letters. 2:170007.
Endale, D.M., Schomberg, H.H., Fisher, D., Owens, L., Jenkins, M., Bonta, J. 2017. Phosphorus, iron, and aluminum losses in runoff from a rotationally-grazed pasture in Georgia, USA. Transactions of the ASABE. 60(3):861-875. Https://doi:10.13031/trans.12053.