Decision Support System for Beef Cattle Production

Kenneth L. Campbell
Department of Agricultural and Biological Engineering

1.0 OBJECTIVES

This research is in support of the overall management goal to develop environmentally and economically sustainable cow/calf practices within the Lake Okeechobee watershed as stated in the Memorandum of Understanding for Agro-ecology Research developed by South Florida Water Management District, Archbold Biological Station, and the University of Florida, Institute of Food and Agricultural Sciences. Specifically, the management objective to which this research contributes is the determination of relationships between agricultural practices and water quality, quantity, hydroperiod, and economic sustainability.

The objectives of this project are to contribute to the above management objective by 1) conducting a thorough literature review concerning the impacts of beef cow/calf production on water quality and wetlands in Florida, 2) modifying and enhancing the FHANTM model for improved performance and applicability to beef management systems, and 3) modifying the IDM decision support system for use as a farm-scale beef production management decision support tool.

Florida is one of the major beef cattle producing states in the Eastern United States with production centered around cow-calf production. Cash receipts from the sale of beef cattle (calves included) in 1990 was $390 million. Over 75% of the nutrients required to maintain a cow and produce a calf come from forages produced on range (3.8 million ha) and pasture (1.2 million ha). These land resources include many unique and environmentally sensitive ecosystems, such as wetlands. Florida has experienced and continues to experience a large (750 people/day) influx of people into the state. The water supply for this expanding urban population originates in large land areas much of which are used for beef cattle production. These factors and concerns for maintaining the integrity of the natural ecosystems have stimulated concern over the impact of beef cattle production practices on water quality and the environment.

Surface water in south Florida is regulated by the South Florida Water Management District (SFWMD) under Surface Water Improvement and Management (SWIM) Plans. Under the Lake Okeechobee SWIM plan phosphorus in surface water runoff from pasture and range cannot exceed 0.35 and 0.18 mg P/l, respectively. Ranchers must adjust their management (grazing, fertilization, etc.) to comply with these regulations. In addition, grazing and roller chopping of wetlands (including maidencane ponds) are being scrutinized by the water management districts (SWFWMD, SFWMD) with respect to water quality issues and habitat destruction.

Nitrates in ground water have long been an environmental concern. The connection between nitrate in drinking water and methemoglobinemia is well established and has motivated drinking water standards on the order of 10 mg N/l. Nutrient enrichment (nitrogen, phosphorus) in lakes, freshwater ponds, and aquatic slough communities has allowed pollution tolerant species (cattails) to replace native flora and reduce species diversity. Dense cattails are poor habitat for wading birds. Since native flora often developed in a phosphorus-limited ecosystem, natural habitat destruction may be occurring.

Conduct a thorough literature review concerning the impacts of beef cow/calf production on water quality and wetlands in Florida.

Technical Approach

Data from Florida concerning water quality impact from grazed rangelands and pastures needs to be analyzed, interpreted, and reported. Currently the data are fragmented among many state governmental agencies (DEP, UF/IFAS, water management districts, etc.). A thorough search of these data from the state agencies in addition to an overall literature search will be conducted. This process must occur before determining research needs in water quality as it relates to beef cattle operations. A comprehensive review of the literature will be completed. A database documenting the impact of beef cattle operations on water quality and wetland functions will be compiled from all available data.

Computer databases (Agricola, CAB, etc.) will be accessed to search for references related to beef cattle operations and water quality. In particular, references of work conducted in Florida will be located and reviewed. A list of all citations will be produced. State agencies will be contacted in an effort to access their data on water quality. Each appropriate agency will be visited and, through a contact person, data will be accessed and reviewed. Additionally, information on site characteristics, management practices from the study sites, and sampling procedures will be determined where possible.

Products and Deliverables

Literature review summarizing the status of current information available concerning the impacts of beef cow/calf production on water quality and wetlands in Florida.

An extension publication providing ranchers current information regarding the impacts of beef cow/calf production on water quality and wetlands in Florida and recommended management practices for minimizing adverse impacts.

3.2 FHANTM Modifications

Objective Modify and enhance the FHANTM model for improved performance and applicability to beef management systems.

Technical Approach

FHANTM (Field Hydrologic And Nutrient Transport Model) is a field-scale model which simulates water and phosphorus movement from individual fields. This model is based on DRAINMOD with modifications to include simulation of phosphorus movement and routing of overland flow. It was calibrated and verified in an earlier study. Sensitivity and uncertainty analysis conducted on the model in this earlier study indicated the relative importance of various parameters to runoff and phosphorus output response. FHANTM was developed for application in south Florida flatwoods watersheds specifically to address issues related to phosphorus transport and its reduction through selection of management systems and practices related to dairies. It is an appropriate tool for use in the beef decision support system because it has proven effective for use in similar conditions on the dairies within the Lake Okeechobee basin. However, the current model needs to be modified to account for the smaller magnitude of phosphorus loadings involved, which changes the relative importance of some components of the phosphorus cycle and related transport relationships. Application of FHANTM to estimate BMP performance for phosphorus reduction in high phosphorus source areas and a model evaluation study revealed several enhancements which need to be added to FHANTM for generalized use in beef production and native pasture applications. The following modifications will be completed under this project: 1) simulation of phosphorus interaction with the soil in adsorption/desorption processes, 2) simulation of phosphorus release from decaying plant material, 3) simulation of the addition of phosphorus by land spreading of manure, and 4) addition of a nitrogen simulation component including transformations, storage and movement with water. Modeling approaches for adding these enhancements to FHANTM will be researched and the most appropriate approaches will be determined. The model will then be modified to include the necessary algorithms and tested using the best existing data currently available.

Products and Deliverables Model code, documentation and users manual for the FHANTM model as modified for use in evaluation of beef production systems in south Florida. A draft manuscript reporting on the above hydrologic/water quality model development and application prepared for refereed journal submission. A final manuscript reporting on the above hydrologic/water quality model development and application, revised to address District reviewer comments. 3.3 IDM Decision Support System Modifications

Objective Modify the IDM decision support system for use as a farm-scale beef production management decision support tool. Technical Approach

IDM (Interactive Dairy Model) is a direct linkage of FHANTM with a geographic information system (ARC/INFO) for use in evaluating water and phosphorus losses from individual dairies in the Lake Okeechobee Basin when various management practices are implemented on individual fields of the dairy. Details of the technical design and implementation of IDM are available in previous reports. IDM was constructed specifically for application on dairies in the Lake Okeechobee basin for evaluation of the water quality effects of specific combinations of dairy management systems. It is an appropriate tool for use in this project because it has proven effective for use in similar conditions on the dairies within the Lake Okeechobee basin. Several major modifications are required for flexibility and ease of use in a more generalized beef ranch type of application. The user interface menus need to be reconfigured to fit a more varied type of management on each individual field of the ranch. Additional experience with development of farm-scale decision support systems since the initial design of IDM will permit development of an improved design for this new generation decision support system. The current IDM decision support system needs to be modified in two other respects. Attenuation of phosphorus from the edge of fields to the farm or ranch outlet needs to be added, and ranch production, management, and financial analysis components need to be incorporated.

In order to account for the attenuation of phosphorus in flowing water from field-edge to farm outlet, algorithms similar to those used in LOADSS (Lake Okeechobee Agricultural Decision Support System) will be developed and incorporated as appropriate.

The existing IDM decision support system does not contain a production-management-financial performance analysis component. This capability will be added to the ranch management decision support system. Two LOTUS-based ranch management simulation models will be used as building blocks for this component. The Cow-Calf SPA model provides standardized performance analysis procedures for evaluating cow-calf ranch operations. The Earman ranch management simulation model links ranch management decisions (e.g. fencing, fertilization, stocking rate) to carrying capacity, beef production and financial performance measures. The Earman model was developed specifically for ranching operations in South Florida and has been used to evaluate several ranching operations in the Okeechobee area. This project will merge the key components of each model into a single ranch management model component that can in turn be linked to the FHANTM water quality model via the modified IDM decision support system. Products and Deliverables

Model code, documentation and users manual for the farm-scale decision support system developed for beef production systems in south Florida.

A draft manuscript reporting on the above decision support system development and application prepared for refereed journal submission.

A final manuscript reporting on the above decision support system development and application, revised to address District reviewer comments.

While the above described tasks of model and decision support system development can be accomplished with currently available information, it is important to keep in mind that model calibration, verification and sensitivity analysis will require field data from experiments yet to be conducted under other statements of work to be developed and submitted for approval at a later date. This will require hydrologic and water quality data at the edge-of-farm as well as field-scale data. Additional information linking pasture management practices to carrying capacity and costs of production may also be required.

All model development will be conducted on Unix workstations using Arc/Info, Fortran, and C software. As in previous projects with the District, the software will be delivered to the District on tape and will be compatible with District hardware and software in current use.

4.0 COLLABORATION AND RESPONSIBILITIES

The UF/IFAS research team for this project includes:

K. L. Campbell, Prof., Agricultural and Biological Engineering Dept.
D. A. Graetz, Prof., Soil and Water Science Dept.
J. Holt, Prof., Food and Resource Economics Dept.
J. J. Mullahey, Assoc. Prof., Southwest Florida Res. & Educ. Center, Immokalee
J. C. Capece, Assist. Prof., Southwest Florida Res. & Educ. Center, Immokalee
C. W. Fraisse, Post-Doc. Assoc., Agricultural and Biological Engineering Dept.
V. D. Nair, Post-Doc. Assoc., Soil and Water Science Dept.

Dr. Campbell is the Contractor Principal Investigator. He will assist with Task 3.1 and will
have primary responsibility for Tasks 3.2 and 3.3 in addition to serving as Project Manager
for the University. Dr. Graetz will have primary responsibility for Task 3.1 and will assist
with portions of Task 3.2. Dr. Holt will have responsibility for the portion of Task 3.3 related to economics and financial management information. Dr. Mullahey will assist with Task 3.1 and portions of Task 3.2. Dr. Capece will assist with all three tasks. Dr. Fraisse will conduct the modeling and decision support system development work of Tasks 3.2 and 3.3. Dr. Nair will conduct the literature review and database compilation activities of Task 3.1. Graetz, Campbell, Mullahey, Capece and Nair will be co-authors of the extension publication resulting from Task 3.1. Campbell, Fraisse, Capece, Graetz and Mullahey will be co-authors of the manuscript on the hydrologic/water quality model development of Task 3.2. Campbell, Fraisse, Holt and Capece will be co-authors of the manuscript on the decision support system development of Task 3.3.

The author can be reached at:
Dr. Keneth L. Campbell
Tel: (904) 392-8534
Fax: (904) 392-4092
E-mail: KLC@agen.ufl.edu