Biophysical & Economic Farm/Forest-Scale Modeling

Through the Participatory Modeling Process (PMP), the project team collaborated with stakeholders to develop farm/forest scale Soil & Water Assessment Tool (SWAT) models for priority production systems in the Florida and Georgia region. The SWAT models were calibrated/validated with project-supported and literature-derived data as well as remote sensing data.

Three representative management systems (MS1-3) for each production system were co-developed by the PMP. The representative management systems were designed to encompass the range of practices currently implemented by producers in the region.

*for Forest MS 2 production systems were modeled with and without pinestraw raking.

Farm/forest-scale enterprise budgets were developed for each production system-management system combination based on interviews with growers and Extension personnel. Inputs and yields from the SWAT models were used to evaluate the net returns for each production and management system using @Risk and Simetar© (Simulation & Econometrics to Analyze Risk) software packages.

Results from the farm-forest scale modeling laid the groundwork for PMP members (stakeholders and project team members) to collaboratively develop a suite of baseline and future scenarios that were simulated at the watershed scale (Regional Scale Modeling).

Florida Farm/Forest Scale Results

Model results for the Santa Fe River Basin in Florida showed large differences in net returns and water quality and quantity impacts across priority production and management systems.

For row crops (corn-peanut and corn-carrot-peanut rotations), MS1 (which uses soil moisture sensors) for irrigation scheduling, reduced nitrogen application rates, and a rye cover crop) decreased nitrate leaching, increased net recharge and maintained approximately the same producer net returns as compared to MS3 (which uses calendar-based irrigation, higher nitrogen rate and no cover crop).

Reducing nitrogen application rates also led to reduced nitrate leaching for both hay and pasture.

Compared across agricultural production systems, the corn-carrot-peanut rotation had the highest net returns, the lowest net recharge, and the highest nitrate leaching. Cow-calf pastures showed lower net returns, but similar net recharge and nitrate leaching to the corn-peanut rotation. Hay operations had low to negative net returns and high net recharge, with hay MS1 having the lowest net returns and lowest nitrate leaching of all agricultural production systems.

Forest production systems in the Santa Fe River Basin generally produced lower leaching than agricultural and forage production systems. They also produced lower net recharge, which varied depending on the tree species and management system. Pine straw raking substantially increased net returns for both slash pine and longleaf forest production systems.

Farm-Forest scale economic-environmental tradeoffs in the Santa Fe River Basin. Numbers refer to the Management System

Key Findings

Net Recharge: Hay > Pasture > Row Crops > Production Forest
Increased recharge for moving crops & forages out of MS3
N Leaching: Row Crops > Pasture > Hay > Production Forest
Decreased N leaching for moving crops & forages toward MS1
Adding carrot to corn-peanut increases leaching by 50-80% but increases net returns by 75-93%
Changing from long- to short-rotation production forest with thinning increases recharge by 10-30% and increases net returns by ~90%

Publications

Athearn, K. (2019). Carrot production budget. [Data set]. North Florida Research and Education Center, University of Florida Live Oak, FL. https://svaec.ifas.ufl.edu/agribusiness/farm-enterprise-budgets/
He, F. (2019). Risk and profitability analysis for sustainable agricultural practices to protect water resources [Unpublished master’s thesis]. Food and Resource Economics Department, University of Florida. https://ufdc.ufl.edu/UFE0055839/00001/pdf
He, F. (2023). Farm-scale and regional economic implication of agricultural land management decisions in the Floridan Aquifer region (30490241) [Doctoral dissertation, University of Florida]. University of Florida ProQuest Dissertations Publishing. https://original-ufdc.uflib.ufl.edu/UFE0059749/00001
He, F., Borisova, T., Athearn, K., Hochmuth, R., & Barrett, C. (2022). Choosing nitrogen application rate recommendation given Florida’s regulatory water policy. American Society for Horticultural Science, 57(11), 1387-1396. https://doi.org/10.21273/HORTSCI16656-22
Koirala, U., Damian, A., Smith, A., Athearn, K., Kastner-Wilcox, K. R., Hancock, G., … Hancock, D. (2022). FACETS enterprise crop budgets for NE Florida and SW Georgia. [Data set]. Ag Data Commons. https://doi.org/10.15482/USDA.ADC/1528358
Lee, D., Merrick, J., Rath, S., Dukes, M., Kaplan, D., & Graham, W. (2024). Groundwater impacts of adding carrot to corn-peanut rotations in North Florida. Agricultural Water Management, 294. https://doi.org/10.1016/j.agwat.2024.108713
Rath, S., Zamora-Re, M., Graham, W., Dukes, M., & Kaplan, D. (2020). Quantifying nitrate leaching to groundwater from a corn-peanut rotation under a variety of irrigation and nutrient management practices in the Suwannee River Basin, Florida. Agricultural Water Management, 246(1). https://doi.org/10.1016/j.agwat.2020.106634
Rath, S. (2021). Agricultural water security through sustainable use of the Floridan Aquifer: An integrated study of water quantity and water quality impacts (28497245) [Doctoral dissertation, Department of Environmental Engineering Sciences, University of Florida]. ProQuest Dissertations & Theses Global. https://ufdc.ufl.edu/UFE0057461/00001/pdf
Reaver, N., Graham, G., Rath, S., Zamora-Re, M., Dukes, M., & Kaplan, D. (2021). SWAT model instances for “quantifying nitrate leaching to groundwater from a corn-peanut rotation under a variety of irrigation and nutrient management practices in the Suwannee River Basin, Florida”. HydroShare. https://doi.org/10.4211/hs.0a7735b121f845f7ab0d1ac6348d9980
Zamora-Re, M., Rath, S., Dukes, M., D., & Graham, W. (2020). Water and nitrogen budget dynamics for a maize-peanut rotation in Florida. ASABE, 63(6), 2003-2020. https://doi.org/10.13031/trans.13916

Meet the team
Wendy Graham, University of Florida
David Kaplan, University of Florida
Damian Adams, University of Florida
Kevin Athearn, University of Florida
Tatiana Borisova, University of Florida
Rob de Rooij, University of Florida
Nathan Reaver, University of Florida
Fei He, University of Florida
Dogil Lee, University of Florida
Unmesh Koirala, University of Florida
Sagarika Rath, University of Florida

Georgia Farm/Forest Scale Results

In general, model results for the Lower Flint River Basin in Georgia showed large differences in net returns and water quantity impacts across crop rotations and relatively smaller differences across management systems within a crop rotation.

Farm-scale economic-environmental tradeoffs in the Lower Flint River Basin. Numbers refer to Management Systems

The cotton-cotton-peanut rotation had higher net returns and higher net recharge than the corn-cotton-peanut rotation. For both rotations, MS1 which used soil moisture sensor scheduled irrigation and more frequent fertilizer application had lower net returns than MS 2 or MS 3 which used less efficient irrigation and less frequent fertilizer applications. Forest production systems in the Lower Flint River Basin had a large range in net returns and a moderate range in net recharge depending on the tree species and management system.

Forest-scale economic-environmental tradeoffs in the Lower Flint River Basin. Numbers refer to the Management System

Restored longleaf and loblolly showed the highest net recharge potential while production longleaf had the lowest net recharge. Net returns were highest for management systems with pine straw production (i.e., slash MS2p and longleaf MS2) while MS1 across all forest types and restored longleaf had the lowest net returns.

Key findings

Publications

Haas, H. (2020). Importance of capturing forest dynamics in hydrological modeling (30272471) [Master’s thesis, Department of Forestry and Wildlife Science, Auburn University]. Auburn University ProQuest Dissertations Publishing. https://www.proquest.com/pqdtglobal/docview/2779135343/BBF54721E93047D8PQ/1?accountid=10920&sourcetype=Dissertations & Theses
Hancock, GA. (2019). An economic analysis of adoption of conservation practices in Georgia cotton and peanut production [Unpublished master’s thesis]. Department of Agricultural & Applied Economics, University of Georgia. https://getd.libs.uga.edu/pdfs/hancock_guy_a_201908_ms.pdf
Koirala, U., Adams, D., Smith, A., Athearn, K., Kastner-Wilcox, K. R., Hancock, G., … Hancock, D. (2022). FACETS enterprise crop budgets for NE Florida and SW Georgia. [Data set]. Ag Data Commons. https://doi.org/10.15482/USDA.ADC/1528358

Meet the team
Latif Kalin, Auburn University
Ritesh Karki, Auburn University
Amanda Smith, University of Georgia
Henique Haas, Auburn University
Guy Hancock, University of Georgia

Biophysical and Economic Regional-Scale Modeling

Land Use Change Modeling in the Little River Basin GA