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United States Department of Agriculture

Agricultural Research Service


Location: Southeast Watershed Research

2010 Annual Report

1a. Objectives (from AD-416)
1. Use remote sensing tools to develop rapid assessment procedures for soil and water resources in Coastal Plain agricultural systems. a. Evaluate tillage and residue management effects on soil carbon accretion, soil water content and associated changes in crop response. b. Remotely quantify variability in crop residue cover to better develop indices that may be used to rapidly assess conservation tillage adoption at the watershed scale. 2. Modify, test, and apply the Riparian Ecosystem Management Model (REMM) to evaluate and guide restoration and management of riparian buffers and wetlands. 3. Develop an improved GIS modeling framework for accurately quantifying soil moisture, evapotranspiration (ET), and infiltration in Coastal Plain watersheds. a. Evaluate techniques for assimilating estimates of soil-moisture at the soil surface into field and watershed scale hydrologic models. b. Improve methods for estimating evapotranspiration and infiltration within Coastal Plain watersheds. 4. Evaluate the effects of land use and surface water features on nutrient and dissolved oxygen levels in Coastal Plain watersheds.

1b. Approach (from AD-416)
OBJ.1: Direct measurements of soil and plant attributes will be related to crop yield and measurable changes in soil organic carbon accretion, soil water content, plant available water content, microbial community size, soil nitrogen, and nitrate leaching. Remotely sensed data will allow us to 1) integrate the combined effects of soil organic carbon accretion and nitrogen management via real-time, non-destructive assessments of crop response, 2) monitor crop response as a function of plant available water and nitrogen contents, and 3) refine crop coefficients for improved irrigation management and water use efficiency. OBJ.2: The Riparian Ecosystem Management Model will be modified to facilitate use for specific applications such as pesticide transport, P retention estimates, and watershed scale buffer scenario testing. Procedures will be tested for integrating modifications of REMM with watershed scale models. REMM integrations with watershed and channel process models will be tested using watershed data collected at ARS and cooperator watersheds in Georgia, Delaware, Mississippi, Maryland, and elsewhere. OBJ.3: A GIS based modeling system will be developed to simulate soil moisture conditions across the region. Based upon existing soil, climate, and vegetation data, the system will allow point, field, and watershed scale estimates of evapotranspiration, runoff, and soil moisture. It is anticipated that the system will be capable of estimating soil moisture across spatially variable fields for purposes of irrigation scheduling, as well as watersheds equivalent in size to the Little River Experimental Watershed for purposes of long term water resource planning. OBJ.4: Levels of dissolved oxygen will be correlated with other measured water quality parameters for 18 sites in the Suwannee River Basin to determine if relationships exist between dissolved oxygen and stream chemistry.

3. Progress Report
Global soil moisture products are now being operationally collected by satellite sensors and generated by space agencies in the U.S. and Japan. The estimates of soil moisture made by these satellites were compared to field data collected across the U.S. including the Little River Experimental Watershed. Measurement of processes affecting dissolved oxygen in coastal plain streams were continued, focusing on the role of leaf litter and dissolved organic carbon in consuming dissolved oxygen. Measurements of water quality in the Suwannee River Basin continued including sampling stations on streams draining an urban area. These sampling stations will allow comparison of water quality and hydrology in agricultural and urban watersheds of the Suwannee River Basin. Completed work to modify Riparian Ecosystem Management Model to estimate outputs of greenhouse gases from simulated riparian ecosystems. Twenty-five farms in the Little River Watershed were surveyed for land use land cover. Satellite data are being processed for NDVI determinations. These data will be used to evaluate spatial patterns in winter and summer biomass production in association with soil quality attributes at the landscape level. A second intensive survey of the 25 farms is scheduled for the Summer of 2011.

4. Accomplishments
1. Ground truthing estimation of soil moisture with satellite sensors. Soil moisture products from satellite sensors have the potential to dramatically improve the accuracy and timeliness of weather, climate, and agricultural assessments and forecasts used by USDA, NOAA, and other agencies. ARS scientists at Tifton, GA compared data collected by the satellites and field data collected across the Little River Research Watershed . Results showed potential correlations but there is much room for improvement, particularly in highly vegetated regions such as the Coastal Plain.

5. Significant Activities that Support Special Target Populations
Dr.Lowrance serves as Chair of the Advisory Board for the Water and Air Quality Center at Florida A&M University.

Review Publications
Truman, C.C., Nuti, R.C. 2010. Furrow Diking in Conservation Tillage. Agricultural Water Management. 97:835-840.

Todd, J., Vellidis, G., Lowrance, R.R., Pringle, C. 2009. High sediment oxygen demand within an in-stream swamp in Southern Georgia: Implications for low dissolved oxygen levels in coastal blackwater streams. Journal of the American Water Resources Association. 45:1493-1507.

Last Modified: 2/23/2016
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