Sabine Grunwald

Geo-Temporal Estimation and Visualization of Nitrogen and other Soil Properties in a Mixed-Use Watershed (Santa Fe River Watershed, Florida)

Research Team
Time
Funding Source
Study Area
Objectives
Results

Research Team

PI:

S. Grunwald, Soil and Water Science Department, University of Florida

Co-PIs:

N.B. Comerford, Soil and Water Science Department, University of Florida

M.W. Clark, Soil and Water Science Department, University of Florida

D.A. Graetz, Soil and Water Science Department, University of Florida

Post-Docs:

C.M. Bliss

G.L. Bruland

Collaborator:

R. Srinivasan, Director of the Spatial Science Lab, Associate Professor, Texas A & M University

Graduate students:

Aarthy Sabesan (M.S.)

Sanjay Lamsal (Ph.D.)

Ownership/use of data from Santa Fe project - Request permission

Time

09/2002 to 09/2006

Funding Source

United States Department of Agriculture (USDA) - Nutrient Science for Improved Watershed Management Program.

Study Area

The Santa Fe River Watershed, a tributary of the Suwannee Basin that drains into the Gulf of Mexico, spans over an area of approximately 3,585 sq. km across eight counties in north-east Florida. The watershed covers about 13.8 % of the Suwannee Basin but contributed 20% of the total NO₃-N loads that drained from the Suwannee Basin into the Gulf of Mexico accounting for about 2,900 tons NO₃-N (Suwannee River Water Management District, 2003). Water quality monitoring data indicated an increasing trend in nitrate-nitrogen concentrations in ground, surface and spring waters, and drinking water wells. Ground water from the Floridan aquifer is the source of the drinking water in the Santa Fe River Watershed. The long-term goal is to maintain and improve surface and ground water quality in the Suwannee Basin.

Fig. 1. Map shows the coastline of Florida and the boundaries of the Santa Fe River Watershed (data source: Suwannee River Water Management District).

Fig. 2. County and watershed boundaries (data sources: U.S. Census Bureau and Suwannee River Water Management District).

The soils of the Santa Fe River Watershed are predominantly sandy in texture with loamy to clayey deposits, organics and sites with sand hill karst terrain with many solution basins. According to the Soil Survey Geographic Database (SSURGO) Ultisols cover about 36.7%, Spodosols (25.8%), and Entisols (14.7%) representing the dominant soil orders in the watershed. Less prominent are Histosols (2.0%), Inceptisols (1.1%) and Alfisols (1.0%).

Fig. 3. Santa Fe River, Florida.

Fig. 4. Santa Fe River, Florida.

Land use (1995) consisted of pine plantation (32.2%), wetlands (16.2%), upland forest (14.7%), improved pasture (14.0%), urban (8.8%), forest regeneration (6.0%), crops (5.0%), rangeland (3.7%) and a variety of high intensity land uses such as tree groves, dairies, and feeding operations.

Specialty land uses in the watershed are diverse, ranging from corn, peanuts, tobacco, vegetables, watermelons, strawberries, blueberries, and pecans. Wetlands and a few lakes are distributed widely in the watershed while urban areas are sparsely distributed.

Fig. 5. Major land cover (1995) and soil types within the Santa Fe River Watershed.

The elevation ranges from around 3 m to over 65 m above mean sea level. Generally, the land is level (0-2 % slopes) to gently sloping and undulating (0-5% slopes), with the major exception to this pattern being the moderately and strongly sloping land (5-12% slopes) along the Cody Scarp.

Fig. 5. Digital elevation model (top) and slope (bottom) - Santa Fe River Watershed (data source: National Elevation Dataset, USGS).

Two main physiographic regions in the watershed are the Gulf Coastal Lowlands and the Northern Highlands, which are separated from one another by the Cody Scarp.

Underlying geologic units include Eocene limestone (which occurs near the ground surface in the high-recharge, strongly karst-influenced Gulf Coastal Lowlands), capped by Miocene sediments which tend to be rather clayey and phosphatic (occurring at or near the surface along the Cody Scarp), in turn capped by Pliocence and Pleistocene-Holocene sediments which tend to be sandy at the surface but having loamy subsoils or substrate at varying depths.

Methods, Data and Objectives

Goals:

Gain better understanding how soil properties are linked to ecosystem processes and environmental landscape properties across multiple spatial scales.

Objectives

(1) Assess space-time variation of soil nitrate-nitrogen across the Santa Fe River Watershed

(2) Develop predictive geospatial models for various soil properties (C, N, P and texture) that incorporate spatial autocorrelation of soil properties and covariation with environmental properties.

(3) Evaluate the effects of environmental ancillary datasets to improve predictions of soil properties across multiple spatial scales.

Data and Methods

(1) Characterize environmental landscape properties: A comprehensive set of spatial environmental data were assembled using the ArcGIS Geographic Information System including: geology, soils, topography (Digital Elevation Model - DEM), land use / land cover, climate, stream network, major roads, and more.

(2) Document land cover shifts in the watershed: Remote sensing imagery (Landsat TM and ETM+) were used to characterize land cover shifts from 1990 to 2003. A complimentary project that investigates relationships between biophysical landscape properties (IKONOS, ASTER, Landsat, and MODIS) and soil properties at multiple scales (ongoing).

(3) Geospatial and temporal mapping of soil nitrate-nitrogen: Soil samples were collected during Sept. 2003, January 2004, May 2004, January 2005, May 2005 and September 2005 from four depth increments (0-30, 30-60, 60-120 and 120-180 cm) in composites proportional to the depth of sampling at ~140 observation sites (random-stratified sampling design). Multiple hybrid/geostatistical methods (e.g. Regression Kriging, Generalized Linear Models, Classification and Regression Trees, spatial stochastic simulations) were used to upscale site-specific observations with the support of ancillary environmental data (e.g. remote sensing data derived landcover, DEM) to the watershed scale.

(4) Geospatial mapping of other soil properties (phosphorus, soil texture, and soil organic carbon): One time soil sampling; 4 depths (0-30, 30-60, 60-120 and 120-180 cm); 143 observation sites: nitrate-N, total N, Mehlich 1 extractable P, and soil texture. One time soil sampling; 0-10 cm depth; 143 observation sites: soil organic carbon and N of 4 particle size classes (2000µ-250µ, 250µ-150µ, 150µ-45µ and <45µ) and P mineralization by particle size class.

Complimentary research projects:

(1) Linking experimental and soil spectral sensing for prediction of soil carbon pools (total, labile and recalcitrant carbon); assessment of carbon sequestration potential at the landscape scale (Santa Fe River Watershed): project link (ongoing)

(2) High-intensity study site - Santa Fe Beef Cattle Research Station (650 ha) nested within the Santa Fe River Watershed: ~150 observation sites sampled at 4 different depths (0-30; 30-60; 60-120; 120-180 cm); soil properties: nitrate-N, soil organic carbon; visible/near-infrared spectral data; topographic data derived from LIDAR.

Results

Peer-refereed publications

Bruland G.L., C.M. Bliss, S. Grunwald, N.B. Comerford, and D.A. Graetz. 2008. Soil nitrate-nitrogen in forested versus non-forested ecosystems in a mixed-use watershed. Geoderma 148: 220-231. (pdf)

Vasques G.M., S. Grunwald, and J.O. Sickman. 2008. Comparison of multivariate methods for inferential modeling of soil carbon using visible/near-infrared spectra. Geoderma 146: 14-25. (pdf)

Vasques G.M., S. Grunwald and J.O. Sickman. 2008. Visible/near-infrared spectroscopy modeling of dynamic soil carbon fractions. Soil Sci. Soc. Am. J. (in press).

Lamsal S., S. Grunwald, G.L. Bruland, C.M. Bliss and N.B. Comerford. 2006. Regional hybrid geospatial modeling of soil nitrate-nitrogen in the Santa Fe River Watershed. Geoderma, 135: 233-247. (pdf)

Grunwald S., P. Goovaerts, C.M. Bliss, N.B. Comerford, and S. Lamsal. 2006. Incorporation of auxiliary information in the geostatistical simulation of soil nitrate-nitrogen. Vadose Zone J. 5: 391-404 (invited). (pdf)

Oral and poster presentations:

Vasques G.M., S. Grunwald, and J.O. Sickman. 2006. Assessment of total, stable and labile carbon using visible, near-infrared diffuse reflectance spectroscopy. Soil and Water Science Research Forum, Gainesville, FL Sept. 15, 2006.

Grunwald S., G.W. Hurt, G.L. Bruland, and N.B. Comerford. 2006. SCORPAN-based soil-landscape modeling in north-east Florida. World Congress of Soil Science - Frontiers of Soil Science, Philadelphia, Pennsylvania, July 9-15, 2006.

Vasques G.M., S. Grunwald, and J.O. Sickman. 2006. Assessment of total, stable and labile carbon using visible, near-infrared diffuse reflectance spectroscopy. World Congress of Soil Science - Frontiers of Soil Science, Philadelphia, Pennsylvania, July 9-15, 2006.

Grunwald S., N.B. Comerford, D.A. Graetz, M.W. Clark, C.M. Bliss and G.L. Bruland. 2006. Digital soil mapping in the Santa Fe River Watershed. Suwannee River Partnership Steering Committee meeting, Live Oak, FL, June 29, 2006.

Lamsal S., S. Grunwald, G.L. Bruland, C.M. Bliss, and N.B. Comerford. 2006.
Geospatial Footprints of Nitrogen Mapped across the Santa Fe River Watershed in Florida. IFAS Research Forum, University of Florida, Gainesville, FL, March 24, 2006.

Bliss C.M., G.L. Bruland, I. Lopez-Zamora, N.B. Comerford, D.A. Graetz and S. Grunwald. 2005. Carbon, nitrogen, and phosphorus in soil size fractions: influence of land use and soil type in a north Florida watershed. ASA-CSSA-SSSA Meeting, Salt Lake City, UT, Nov. 7-10, 2005. [poster]

Grunwald S., C.M. Bliss, G.L. Bruland, I. Lopez-Zamora, D.A. Graetz and N.B. Comerford. 2005. Geospatial modeling of phosphorus within a multi-functional and multi-use watershed. ASA-CSSA-SSSA Meeting, Salt Lake City, UT, Nov. 7-10, 2005.

Bruland G.L., C.M. Bliss, S. Grunwald, N.B. Comerford and D.A. Graetz. 2005. Soil nitrate in forested versus non-forested land-uses in the Santa Fe Watershed, Florida. ASA-CSSA-SSSA Meeting, Salt Lake City, UT, Nov. 7-10, 2005.

Stoppe A., C.M. Bliss, N.B. Comerford, D.A. Graetz and S. Grunwald. 2005. Phosphorus and nitrogen in soil size fractions: mineralizability of each fraction as affected by land use and soil type. ASA-CSSA-SSSA Meeting, Salt Lake City, UT, Nov. 7-10, 2005.

Lamsal S., S. Grunwald, G.L. Bruland, C.M. Bliss, and N.B. Comerford. 2005. Modeling of regional soil nitrate-nitrogen patterns using a mixed geospatial modeling approach. Pedometrics 2005 - International Meeting of Commission 1.5 of the Int. Union of Soil Sciences. Naples, Florida, Sept. 12-14, 2005 (Graduate student Sanjay Lamsal ranked 2nd in the student award competition). [poster]

Bruland G.L., C.M. Bliss, S. Grunwald, N.B. Comerford, and D.A. Graetz. 2005. Contrasting soil nitrate-nitrogen across land-uses and soil orders in a north-central Florida watershed. SWS Department. Research Forum, Gainesville, FL, Sept. 2, 2005. [poster]

Lamsal S., S. Grunwald, C.M. Bliss, G.L. Bruland, N.B. Comerford. 2005. Regional modeling of soil nitrate-nitrogen with auxiliary environmental datasets in the Santa Fe River Watershed. SWS Department. Research Forum, Gainesville, FL, Sept. 2, 2005 (Graduate student Sanjay Lamsal won poster award).

Grunwald S., G.L. Bruland, S. Lamsal, C.M. Bliss, N.B. Comerford and M.W. Clark. 2005. Development of predictive geospatial soil nitrate-nitrogen models in the Santa Fe River Watershed. CSREES National Water Quality Conference, San Diego, CA, Febr. 7-9, 2005.

Sabesan A., S. Grunwald, M.W. Binford and M.W. Clark. 2004. Backcasting of land use pattern using remote sensing to support soil-landscape modeling. ASA-CSSA-SSSA Meeting, Seattle, WA, Oct. 31 - Nov. 4, 2004. Abstract No.: 5000.

Lamsal S., S. Grunwald, C.M. Bliss, I. Lopez-Zamora, M.W. Clark and N.B. Comerford. 2004. Comparison of multivariate non-parametric methods for predictive modeling of soil properties in a mixed-use watershed in Florida. ASA-CSSA-SSSA Meeting, Seattle, WA, Oct. 31 - Nov. 4, 2004. Abstract No.: 4997.

Lamsal S., S. Grunwald, C. M. Bliss, I. Lopez-Zamora, N. B. Comerford, M.W. Clark, G. W. Hurt. 2004. Spatial upscaling of site-specific nitrate-nitrogen measurements to the watershed scale in the Santa Fe River Watershed. SWS Department Research Forum, Gainesville, FL, Sept. 2, 2004.

Lamsal S., S. Grunwald, C.M. Bliss, I. Lopez-Zamora and N.B. Comerford. 2004. Upscaling site-specific nitrate-nitrogen measurements to watershed scale in the Santa Fe River Watershed. Soil and Crop Science Society of Florida, Tallahassee, FL, May 20-21, 2004 (Graduate student was awarded price in student competition).

Sabesan A., S. Grunwald, M.W. Clark, N.B. Comerford, D.A. Graetz and R.B. Brown. 2003. Targeting sampling locations using GIS and remote sensing datasets. ASA-CSSA-SSSA Annual Meeting, Denver, CO, Nov. 2-6, 2003, S05-sabesan265102-poster.

Sabesan A., S. Grunwald, M.W. Binford and M.W. Clark. 2003. Linking land use dynamics to soil and water quality using geographic techniques. Soil and Water Science Departmental Research Forum, Gainesville, FL, Sept. 4, 2003.

Lamsal S., S. Grunwald, N.B. Comerford, D.A. Graetz, K.M. Portier, W.G. Harris and G.W. Hurt, G. 2003. Development of holistic, quantitative soil-landscape models in north-eastern Florida. Soil and Water Science Departmental Research Forum, Gainesville, FL, Sept. 4, 2003.